The idea behind using gravel is that when the water level goes down, the gravel will dry out quickly, whereas soil will retain moisture. If your groundwater level is above the base of your post, there is nothing that is going to stop it from getting wet other than a membrane. The only thing you can do when wood is in the ground is ensure that what surrounds the post dries out as fast as possible once the water level goes down. Bacteria needs moisture to work on the wood. Also, water doesn't always follow the path of least resistance, that is an electrical principle. Consider capillary action. When you stick a dry towel in water, it will wick the water upwards against gravity, which is not the path of least resistance. Soil also has capillary properties. Not trying to argue, just adding to the conversation. Thanks.
I only know my personal experience with "cracking clay" in Dallas. Notorious for cracking foundations. I've been at this house for 30 years & every post I've replaced the only one's that had no rot below the soil were entirely encapsulated in concrete. I'm not saying anything about the gravel approach. I'd have to see 1st hand. There is enough confirmation bias in the world creating willful ignorance. No need in me adding to it. Lol You got me to thinking. Does the gravel approach leave the bottom exposed or not? I'm guessing it does.
@@iceebalboa3177 I'm guessing the "cracking clay" you are referring to is some sort of expansive clay, which means it expands when it's wet and thus will flex and break a foundation. Here in Mississippi, we have "blue clay" which is expansive and "red clay" which is basically a blend of sand, clay and minerals that packs hard and doesn't expand much when wet. As far as your question goes on the gravel approach leaving the bottom of the post exposed, basically, you put several inches of gravel in the bottom of the hole, then place the post, then fill the hole surrounding the post with more gravel. Rain fills the hole at which point the surrounding soil wicks the water from the gravel filled hole through capillary action providing the soil type has such properties. Again, this is the idea behind it. I haven't done vigorous experiments, so I too will digress from adding to the confirmation bias.
@@johndoby It's just really bad down here. Heck, I'm originally from Hays,Kansas but even after moving to TX at 10 I have no choice but to be a nonconformist. I have varying views, so not only am I often automatically dismissed, I once had white folks talking down to me so bad I began wondering how I'd feel if I wasn't white. Dallas is my 6th city & been in this mess since I was 16. I can't do phoney & most people who move here conform or don't draw out all the arrogance from people the way I do. It's funny I'm always smiling & people tell me I lift them up. I like people. Sometimes I wonder if they don't like that I do. Their confirmation bias probably plays a part in why I always put myself in other people's shoes. I could write a book on these people. The entire world would believe it, except for a Dallas native. They'd say I was jealous & believe it because they flatter themselves that way. The older I get the more toxic this environment becomes
I've dug up wood that was used as shoring near the Delaware River, the wood was put there throughout the 1800's, it is always in pristine condition when digging to repair the sewers.
I am amazed that there are so many knowledgeable people here with so many years of experience with wood posts in the ground, yet no one seems aware of the fact that if a french drain were added into the picture, it would barely matter which method one uses for planting their wood posts. Have you ever heard of a post rotting when the structure had a perimeter french drain? As for fence posts- no, one would not bother to put a drain, but sleeving them would do just fine. Nowadays, sleeving is so cheap and easy to do. Whether with just motor oil and diesel, or PE wrap. No muss, no fuss. I know of spruce posts (yes, spruce) that are sleeved and good for some twenty years so far and going great.
After gardening for 30 years, I suggest keeping soil away from wood posts. Soil is the fastest way to rot because it gives soil-borne bugs, fungus, and bacteria a direct path to eat the wood. Using a gravel layer on the bottom helps slow them down and allows excess water to drain out (in most reasonable draining soils). If you have long-standing pooling of water, consider tar or other waterproofing but don't let the soil touch the wood.
@@aldoconciso I have seen people burn the outer layer of the wood with fire or a torch. Insects don't like it as much and it is semi-waterproof. I just did that for some 6x6 steps and laid them on a layer of gravel.
@@bibleboardgames i've also tried burning them a bit on a bonfire. Still standing, but it's time consuming if you have many posts to treat. I'll try smoking a batch with a torch, thanks!
My method for a standard 6’ high fence in heavy clay: drill hole 8” diameter / 30” deep with auger; insert 8” diameter cardboard form leaving about 1/2” of form above final grade; fill any unevenness between form sides and hole with loose, dry soil mixed 50/50 with coarse sand, then water in; place 6” of crushed medium granite in hole and firmly tamp; coat bottom 25” of post including base surface with asphalt roof sealant; center post in hole; fill around post with same medium crushed granite, tamping firmly as you go, stopping 6” from top of tube; fill remainder of tube with Quikcrete and slope surface so about 1/4” of the asphalt shows. A couple notes: 1) Water does not flow in wood. It wicks thru capillary action until saturated and gravity has little effect on this wicking. By sealing the post with asphalt below-grade, the only way for water to saturate the post at and just below grade (where rot is most likely) is for it to be wicked in from above-grade. The asphalt coating will not act as a cup for water accumulation - as the post dries any moisture will be wicked up and out. If you asphalt seal below-grade, and stain above-grade, very little moisture will find its way into the crucial rot zone. Without excessive moisture there will little in microbes or fungus and thus no rot. 2) The 6” Quikcrete cap acts like a lid to prevent the hole from filling with runoff. Any moisture that finds its way between the Quikcrete cap and the asphalt-coated post has nowhere to go but down into the gravel. If you really want to be thorough you can fill any gap that eventually forms between post and concrete with tube asphalt and a caulk gun. You can also use concrete sealant on the cap, and since it is not driven or walked on this sealant will last a very long time. The cap will not heave since there is 24” of crushed granite under it.
I'd heard the gravel idea. In a lot of the UK we have heavy clay, and the inherant slow draining, but the water table is often several feet or even several yards down. We tend to have steady rain rather than heavy rain (though this might be changing) and so, while the ground is often soaked, it isn't actually flooded with water. So, if you dig a 2' depth hole in the ground and keep it covered, the hole does not fill up with water. This being the case, I think, in these conditions, gravel would not cause a problem even in clay, and since there are no fines in the gravel, the water would not be able to soak into the gravel as the gaps between the stones prevent caplilliary attraction: any water would drip to the bottom of the gravel pit, not soak to the top. The advantage as I see it is that small quantities of water that may be able to get in between the post and the concrete are not forced to wait to be absorbed by the timber or the concrete - they can simply drip down through the gravel (emphasis being on the quantities being small, otherwise, as you say, the gravel just fills with water. But obviously, as you say, soil varies immensely from place to place, and that's what I am taking from your video. You've made me think. Thank you!
You always have interesting comments and provide us with a different perspective of how things are done in the United Kingdom and they are always appreciated. Thanks for watching and taking the time to share interesting stories, when you would probably rather be at the pub.
Interesting you say that about the rain. Seattle is being the same way. I am used to a much more steady low rate rain. We have been getting heavy rain, what seems like, a lot more. And then a lot more dry in the summer.
Having been in forestry and sawmilling in the UK for over thirty years. I can assure you most posts will rot faster in concrete. Especially oak. Oxygen and damp is the perfect environment for rotting so above ground drys or seasons and deep down waterlogged wood with no oxygen is unaffected. We used to ram the posts in with layers of soil then small stones a few inches at a time. The old estates used to air dry their fence posts for years before using them and would often tar and charr the bottoms. Just the charring makes a big difference.
Got a kids play-set from a man giving it away 10+ years ago and cemented the 4x4 posts in the ground. This weekend I dug them up to give to a friend with children. 6 of the 8 posts looked absolutely perfect. 1 post had some decay and another had quite a bit as well. Honestly I think it depends on the wood itself and maybe how well the concrete forms around the post.
If you keep wood either dry, or wet; it will last indefinitely. What destroys wood, is the wet dry cycle. When it is moist, it is attacked by carpenter ants and termites. When it dries, the fibers become distorted, and they break under tension, accelerated by dirt replacing the water. There is more empty distance between the fibers where the water used to be. If you put a post in just gravel, it will last longer than one in concrete. As noted, concrete is porous, and it holds water longer than gravel alone.
You would think, at this point, that we could actually have *data* on what works best in what climates. All we get is a bunch of videos and comments with "I always do it this way and it works".
I agree, but I don't think there is a way to prevent the wood from rotting without using pressure-treated lumber design specifically to be buried in the ground or have contact with concrete that is buried in the ground. In other words, I haven't came across a cost effective method that works or one that works in different parts of the world.
@@gregvancom I paint the bottoms and sides of the posts up to three feet with roll on bed liner material I just began doing this and I expect the material will prevent rot under the painted areas long after I die.
First off, how old are you? If you're 85 years old, then your prediction might be correct, but if you're 20 years old, you will have to let us know what happens in the future. :)
I use gravel no matter what soil. 1st is help stabilize the post in all direction. 2nd it help grade the post. I also pour concrete on the top of the gravel to seal the bottom of the post. then pour the rest of the hole for strenght
You're making much sense Greg and your point gets across. Physics rules and you're going by that, even if you might not explicitly mention it. I've been thinking for a while about the issues presented here, as we've got a very heavy clay soil in our property, and realized couldn't take a "one size fits all" approach. The type of soil one got matters a lot. Thank you for sharing your ideas and experience
I would never encapsulate the wood in concrete. I have posts I did 22 years ago which I did with gravel at the bottom and they are still going strong. I angled the concrete like you said as well. However the pressure treated 4x4s have shrunk over the years (1/8th inch maybe on each side) so there is a small gap around the perimeter of the wood/concrete where water definitely would go into the bottom of an enclosed encapsulated concrete base versus draining as it does now with gravel. I live in Texas gulf coast. I see your point about standing water but I don't think I have standing water as you illustrated for very prolonged periods of time. Hence I am going with the gravel approach when I have to do it again based on 22 years of success in my case. Encapsulated might be ok if you could seal the wood shrinkage issue and keep water from flowing down into the enclosed pocket. Thanks for video. Interesting discussion for sure
you can fill up the gap between the wood and the concrete with some silicones ( not the stiff ones) , the ones used by carpenters/windowmakers to fix the glass in windows and doors for example
I dug a 2 foot deep hole today for a mailbox post that is 6x6, 5 inches of topsoil and then clay down to the 2 foot depth. At first there was no water but after 30 minutes there was 1/2 of water at the bottom. Setting the post tomorrow, will be interesting to see how much water is in the hole when I'm ready to set the post. It may be completely full we will see. Any thoughts on painting the wood with a thick coat of silicon? I did paint the post with 3 coats of exterior paint. I did use ground contact wood. I was going to use gravel but I see this is probably not a good idea.
Kind of depends on the type of gravel too there's a lot of variables here. Three-quarter or 5/8 with fines packs really well probably won't hold much water especially when compacted. It makes sense to put 5/8 or 3/4 crushed rock with fines at the bottom of the hole because it is not dirt which has bacteria in it that attacks wood. Here in the Pacific Northwest dirt generally retains more water. The biggest issue I've seen is when vegetation / bark dirt grass, dead grass collects against the bottom of the fence post for years and has a tendency to collect the rain and soak the bottom of the post and that creates a rot situation.
I feel good that you report what I had guessed would happen - water pooling in the gravel. It's simple. Whatever is heavier displaces what's lighter. Gravel has lots of air....which gets displaced by water - instead of dirt. Yikes!!! Thanks. This was just an thought thing for me.
Here in Canada the biggest problem is most often frost heaving the forms and carrying the post along...among other precautions I'm told gravel well placed, reduces the ability of freezing soils to get a hold on the concrete...As far as moisture, I know one guy who tars then wraps wooden posts in garbage bags, then concretes them in. I'm curious what you think about this idea? I've never gone to check back over time how this method stands up.
I agree, the frost is the biggest problem here. In my area I have to go at least 6ft down to be under the frostline and build the base wider then the concrete column to keep them from moving. I don't see why tar and plastic bag wouldn't work. Sounds like it would seal up nice and protect the post from beeing soaked in water.
The main benefit of using gravel in post holes in low-lying areas isn't for drainage at all; it's to help lock the post in place. It's much more difficult for the post to start leaning when it's surrounded by gravel than it is when it's surrounded by wet soil.
I'm wondering if that would cause the post to retain water if it entered from on top, but sounds like you will have a roof over it. Might get some sideways rain or splashing but hopefully not enough to saturate the wood.
Mark post 6” above ground and tape round that line and bitumen paint the whole bottom of the post, let dry then concrete. They rot above the ground where air and moisture get in. Had posts in 20 years and no rot yet. Always put a top cap on the post to stop water getting in the end grain.
I've never used gravel below one-off posts for mailboxes or retractable hoses, etc. I've shovel-dug the holes, set about 1/3rd of the post into the hole, then filled with fast-setting Quikrete then soaked the whole area with a garden hose. Cedar 4x4's have always worked best for this type of one-off installation. Cedar can take decades to rot even if it's continually exposed to water. My mailbox post has remained level and solid for over 7 years, despite the freeze/thaw cycles and harsh winters we have in Western NY. For decks/fences and other wooden structures that need to remain level with proper drainage, I would opt to use a few inches of gravel below those posts, primarily for leveling purposes. Overall I would agree that the gravel probably doesn't do too much if anything to "drain" water especially in heavy-clay soils, which is what I have in my area (the entire NE US is mostly clay soils). Doubtful that a few inches of gravel would prevent decay from water exposure, unless you live in an area with a dry climate and sandy/gravel-filled soils...and I wouldn't bother with gravel if my soil was sandy. I've pulled cedar posts that were in the ground for 15-20 years and I have yet to see one with substantial rot.
used stripped cedar post with no concrete for fence post. 25 years later still doing its job. Also, concreted corner support cedar post. Couldn't speak for use as supporting beams.
What you don't want is the wood getting wet and drying out many times. In the graphic shown in the video, the best way to do it is wrap the portion of the post that is encased in concrete with a moisture barrier like roofing felt.
I don’t think it is for standing water. It just speeds up the drainage in case of water coming from above (rain). It doesn’t solve the problem, but it shortens the time when it is wet, adding a few years to its lifetime for cheap.
Forget the concrete. Put some gravel in the hole, put the column in and the place gravel around post and compact as much as possible in lifts. The more the post wiggles the tighter the gravel gets. For extra protection coat the part of the post going in the ground with an asphaltic foundation coating.Keep in mind if you cut the post you lose your pressure treatment so the cut part of the poss has to be field dressed with a preservation sealer. The wood should never be in contact with the soil on the end grain.
My experience was just the opposite re: the base (with a clay soil), but the sloped top of the concrete is crucial. I replaced our fence a couple years ago and the concrete at the top was not really well placed. It looked as though it has been just shoveled into the hole around the post below grade and almost funnel-shaped. The wood at the top of the concrete was rotten; the fence was falling over. But when I dug up the post base pieces, the wood sticking out under the concrete was fine! I think that the clay soil fills the gap soon after the post is placed and that blocks moisture from moving into the space around the post base. Remember, even with clay soil moving water will carry that soil into the voids (whether it’s gravel or just loose soil.
Like he said wood needs air to rot. Air can move through concrete. best to keep concrete covered with clay. but dont let posts be a low spot to pond water around.
I think in most cases your better off coating the pressure treated post with used engine oil or tar about an inch above ground to the bottom. Then just foot it in gravel and then layer the gravel and soil up the post every few inches. Then it keeps it stable, no freezing/heaving problems and everything drains and pulls moisture from the post. If you have to just pour concrete at the bottom to keep it from moving in sandy soils.
I removed two posts today. One had rotted at the top where it was inserted into concrete, due to the soil around it. The other was not rotten, but was softest at the base. I suspect it is often more important to ensure concrete extends above the soil level.
I installed fences 35+ years ago with gravel and they are still standing. The wood acts as a wick so I put 6 inches to 12 inches of rock. I do the same thing in planting in pots. I put an inch of rocks so they don't get root rot. Many old timers use diesel and oil mixture to soak the ends as well.
The solution I have found when installing wood posts in damp soil is to dig a trench and install 3" wrapped flexible corrugated perforated drain pipe 1-2 feet away from the posts and parallel to the post line. Lay the pipe about 4" deeper than the post bottom and run it out out to daylight (I have a gulley) on a drain grade (-1/4" in 10'). Put 6" clean gravel under the post footing and over to the drain pipe. Lay some filter fabric over the gravel or wrap it to keep the dirt out. Or you could run the drain pipes to a dry well and pump out the water. I have sandy soil and my treated posts still rot off at ground level unless the concrete comes up above ground. I rented a trencher machine for a day and retrofitted 4 pole barns and and several hundred feet of wood fence with drain pipes in 2 days by myself. Way cheaper than jacking up a building and replacing the rotten post bottoms.
Could you pour the concrete into a contractor grade plastic bag. Wouldn't that keep or slow down the water getting into the concrete. And also pretreat the wood post. with 50/50 oil/kero.
@@gregvancom eucalyptus is a strong timber, however timber density is no deterrent for our termites or fungal attack in Australia, if untreated in the ground. Australian turpentine hardwood is use in marine environments for wharf piles around the world. Another Australian species “cypress pine” is termite proof, dense and used for flooring.
Great info,, was about to say a lot has to do with the soil, weather conditions....etc, pre treatment of timber,, I always put extra on my sub level and never had issues
Been researching this for years - when building decks and fences, etc... I"m building a log building and I'm using 10-12" log posts and I'm thinking I'm going to copper coat them, then put them in about a foot of concrete at the bottom, then dirt for 2 1/2'. Every few years I'm just going to dig around them about 1-2' deep re coat. I guess the absolute safest method would be brackets on top of concrete, but those are expensive and I kinda don't trust brackets for a building in regards to lateral movement..
I'm not 100% sure what you doing, can you provide me with more details or email me some pictures. Keep in mind that I am not a structural engineer and will only be able to provide you with an opinion.
@@gregvancom . Copper coat from Home Depot helps with fungus and bugs and rot. I had planned to coat them with that and then maybe Liquid Rubber, since they will be covered and rain water won't get between the wood and the coating. Instead of fully encasing them in concrete, I was thinking about a donut of concrete toward the bottom just to stabilize. I was thinking of recoating them about a foot deep, with rubber or copper, every 5 years or so, even though I might not need to since they are under a roof and the soil is clay like. Hope that makes sense. The plan is still evolving.
Interesting and informative video with lots of great comments. From my perspective, the only way gravel would be effective for very wet environments, is to widely excavate the entire fence line and back fill it with gravel. Then, add a drainage system to the lowest portion of the gravel bed. A pipe with holes drilled into the top edge comes to mind (perforated drainage pipe with holes facing upwards and sideways). The perforated drainage pipe would need to be plumbed into non perforated drainage pipe pipes on the low side of the fence line. The wetter the soil, the more drainage pipes (possibly using T connections) leading to low elevation would be required to move water away from the fence posts along the entire fence line. I would probably seal the bottom foot or two of each post with a heavy-duty watertight membrane similar to what is used in shower deck installations. Lastly, I may even consider covering the gravel with an inch or so of concrete to help minimize moisture hydraulically penetrating the gravel if or when the water table rises to the topmost area of the gravel. Again, this is just what I would consider doing if working in moisture challenging environment. To be sure, I am no hydrologist, not a trained fence builder or contractor, and probably have no business even suggesting what I would do. The topic was interesting, and I believe everyone's perspective can be useful. Mark Nicholson (Retired) Former, US Army - EFMB, Combat Medical Specialist 1/94 FA MLRS - Erlangen West Germany 690th, Medical Company supporting Misc. Weapons Ranges, Airborne Jump School and Ranger Training Brigade (ARTB) - Ft. Benning Georgia
What’s your recommendation for a fence post that does have a high water table? Currently that is my situation. Install metal poles under frost line? Install helical metal posts?
This isn't an easy question to answer, but I would probably go with metal. However, drive around your area and see what others might be using to see if something else is working better.
I feel like if your local water table is that high, maybe consider a solid cement pier with the wood attached on top or go with vinyl fence posts. I don’t think I’d ever build a wooden fence that I know is going to be constantly submerged.
From my experience, unless your yard is desert-like, I don't think you should use concrete with wooden posts. They rot too quickly when parts of the post are in concrete. Concrete is for steel posts . If you worry that the fenceline wooden posts will lean, use bigger, longer posts, and tamp them well. If you're worried about corner posts, make them bigger and longer, and cross brace them to adjacent posts or struts. I think it helps to use the wooden posts with creosote bottoms. The creosote should reach above ground level. I think it helps to mound the soil around the base of the post to avoid puddling water. In my area, heaving is not a big problem unless the posts are shallow, and the concrete is also shallow. We tend to have clay below 12". We're semi-arid with Winter temps rarely below -10.
I think it's better (and a lot easier/faster) to drive them in. A backhoe bucket full of dirt or gravel can push a 6" sharpened round fence post in pretty well. A little tap-tap-tap is sometimes required. They will be tighter than most people tamp them in. Haven't done square posts, but should work just as well.
That sounds good, but you would need a backhoe and someone like yourself who could push them in straight enough to create a nice looking fence. Sounds like digging a hole might be better for me.
I've done it that way on some soft soil. We mounted a chain on the bucket in such way that you could judged where plumb was from the cab of the tractor. You either want the posts cut straight across, or have them sharpened to a 4 sided point. Wedge points tended to drive crooked. Chisel points go very crooked.
Lots of rock in my area so I put the post on a rock at bottom of hole. Then add concrete. Rock may help keep moisture off post. Used this procedure and privacy fence is still standing after 30 years.
I have just replaced a fence post at the weekend and it had no gravel at the bottom. Do you know what section of the post was most rotten? The part that was at ground level. The base of the post and about 10 inches above that was in significantly better condition. The base of the post was not treated to any preservatives. In conclusion, adding gravel or any other substrate to the bottom of the hole is largely a waste of time.
I have several full 4x4 pressure treated post that have rotted at the top of the concrete piling, where the post meets the concrete. When I pulled out the piling the bottom of the post was like brand new, no rot at all, solid. Gravel was not used in the bottom of the hole, direct contact with the soil. It was clay soil also. These post have been in the ground for at least 35 years. Can’t explain it. Anyone know how to get a slop concrete top using Quikrete?
For rot to start you need three things, moisture, air and the microbes that attack the wood these three come together at or just below ground level. Putting gravel in the bottom of the hole makes a void for water to collect but if there is little or no air down there them the water will do little harm or even any good.
Your absolutely right. After seven years or so my posts are rotting from 5 “or 6” underground . Everything deeper or above is fine. Painting the new posts with copper napthate then tarring them. We’ll see how they do if I live long enough.
@@craigkeller Every time a post gives way at or just below ground level dig out the stump and while it might not be on good condition it will be far better than the point of rot.
@@craigkeller Thank you, there has been so much ROT talked about posts rotting. IT IS THE FEW INCHES ABOVE AND BELOW GROUND THAT ROT FIRST. Someone suggested wrapping felt round the post but unless you can make an air/water tight seal (virtually impossible)at the top of the felt it will let moisture in between post and felt, the same with concrete, post shrinks and swells and lets moisture in. One tip I heard many years ago is to drill a hole 1/2 ins or so at 45 degrees from just above ground level to just below and about 3/4 the way through. Fill this hole with preservative and plug with a removable cork then every year or so go with an oil can and squirt the hole full of preservative.
I have a theory: What if we set the bottom of the post in 6" of concrete at lets say 4' down and in the centre of a 1 squarefoot area.. Then, we trench around the perimeter of that 1 squarefoot area 6 inches deeper than the bottom of the concrete, so a 4.5 foot deep drench.. We then fill the bottom of the trench with 6" of gravel making the path of least resistance below the bottom of the concrete/post... and then backfill the trench with dirt and place sod.. Just like we do for drainage systems around residential footings.. What do you think @gregvancom ?
That sounds like a lot of work, but definitely something that will allow water to drain into the gravel easier than it might in other soils, especially clay. However, it might not work as well in areas with higher water tables or in areas or the soil retains water for longer periods of time. The gravel can actually form water collecting pools and make the situation worse.
@@gregvancom Thank you for the response!! I live in ontario where the frost level is at 4' so all concrete footings need to be below the frost line. I'm a first time homeowner and your videos have helped me tremendously when it comes to understanding building construction and making the best possible decision for laying out my projects. I have an old 1940s cape cod style home with 4 exterior walls resting on concrete footings and a 18" crawlspace with a centre support beam spanning the length of the home, The home is split down the middle with a wall directly over the crawlspace beam.. On the left half of the home it is completely open from front exterior to back exterior wall.. It has a knee-wall attic and I would like to vault 1/2 of the ceiling of the left side of the home (1/4 of the homes entire ceiling) (15' x 11.5') to make a balcony loft/mezzanine .. So far I have sistered on 2x6 exterior walls and 2x10 floor and ceiling joists.. My plan was to install a 4"x12" beam from the exterior wall to the center wall (11.5') and then install another beam lengthwise (15') connecting the 4"x12" beam to the exterior wall in order to support the roof rafters.. Would this be sufficient or would additional support be needed to handle the live load of a mezzanine? would you be able to make a video if I sent you a rough blueprint drawing?
@@auntjemima5120 You're welcome. It sounds like you need engineering advice and I cannot provide that. I also don't make free videos that offer specific design information for individuals. However, I don't mind taking a look at building plans and answering other questions if you have them about building.
Don't Google it. Ask a contractor or ask your neighbor. My next door neighbor was taking a fence down after 20 years, I helped him pull up some posts that were set without concrete of any kind, but simply with pea gravel. These posts were still in perfect shape, just as good as the post above ground. So when I put my fence in, I used his exact technique. Clay soil with okay drainage, but we have the same soil, the same slope and all that, so I'm banking on the knowledge of those who came before me that my fence will do allright. I packed it tight with pea gravel and the fence is still upright and plumb after 60 mph winds coming through town.
Use cedar if you can, go below the frost line so it won't heave, use a string to keep the posts in a straight line so it looks good, use a heavier post to hang the gate on, and it will last for 25-30 years. Every fence needs work/replacement after that.
What if you put the wood on top of the concrete where you use hardware? Post never enters the ground/concrete? More expensive but will it lasts longer?
This is what I normally do, for the wood that is going to be in the ground, I give it a coating with the liquid compound you use on roofs first. then when it has dried, then place the post in the hole and fill with the desired amount of concrete. So far it has worked very well!
I live in Houston a few feet above sea level. It rains most of the year so the clay soil stays wet; dries out to a crust in the heat. It's anecdotal but I've done that for years with great success. The roofing asphalt keeps anything from wicking up the end grain and creates a barrier when that void forms as the wood shrinks back in the concrete during the dry times. My current fence set with that method is over 20years old with no rotten posts.
I feel like this is probably the best way to go about using wooden posts. Seal the wood so that it cannot absorb the water and you'll have no rot. I'm also curious, if you use the old technique of burning the surface portions of your post that will be subsurface, will that also help? I know several people who build using old methods and they do this, seemingly with great success. No chemicals needed with that method.
@@t-6273 Any method that shields the wood from rot is good in my book. When I coat the bottom of the posts, I make sure the coating goes 2-3” above the surface of the ground.
I don't think the bottom matters either way because it will wick a few inches up if that's the case. But no concrete anywhere. Pack it in with dirt and gravel as you backfill. I've redone 100 year old farm fence posts that were just dirt and not that bad and I've took out 10 and 20 year old Cedar and treated posts that were rotted bad because they were covered in concrete.
At the end of the day , soft wood will only last so long outside. I dip the ends of my posts in tar or bitumen up to where the concrete will finish . let it dry off and concrete just above ground level as you've shown on this vid .
What about water(Rain) getting between the post and the concrete? it has to go somewhere or it will sit an rot the post out quickly. If there is a drain at the bottom it has an exit. Also there is water in the post on new post that needs to exit or dry out too.
Wish I could show you a picture of the concrete fence post my father and I used to make. His first fence using them back in 1977, was just recently rebuilt with new lumer, but the concrete post still standing straight are still going strong.
"The perfect fence post and concrete design..." Well, almost. The corners of the posts should be radiused wherever the posts are encased in concrete (normally from the bottom of each post to about an inch above the expected concrete level). This rounding removes the sharp corners of the post (stress raisers), significantly reducing the probability of cracks forming in the concrete at those points.
if the post is fully encapsulated in the concrete then the concrete will do the same thing the gravel will do anyway. the gravel is definitely pointless. also as you stated the dirt will make its way in to the gravel anyway and youll actually have another problem develop even if its not severe which is cavitation. how do you solve that? filter fabric but even with that itll get clogged up over time and end up retaining water more than the dirt itself would. plus im not really sure why there is so much talk about protecting the part of the post that is in the ground when ,as far as ive see, its always the last thing to rot away. the part thats in the ground always lasts longer no matter what extra step you take to prolong the inevitable. seems like a lot of effort to fix a problem that is redundant. if you are using concrete for a stable foundation then there is no reason to do anything else. if you are just driving the post in bare then the only thing you need to worry about is protecting the first 6-12 inches that is making contact with the top soil.
It doesn't make any difference to me. I have clay soil and it holds water really good. I am at the bottom of a hill so water comes to me. I will say my fence has lasted seventeen years and I am at the point where I have some leaning post. I have stained and waterproofed at least 3 times and all of my neighbors fences are in worse shape than mine. One thing that helps is that I keep grass away from my fence bottom. My weed eater did cut into the wood at the bottom of the pickets so I took a laminate saw cut about an inch off the bottom of the fence to make it easier to weed eat under the fence as well. It look much better too. A note about stain. Using a dark stain on your fence looks great when you put it on but after the birds get through with it you might as well have painted it white.
Wouldnt it help if the wood post was completely sealed with something like a polyurethane sealer prior to putting the post in the ground to stop the moisture from absorbing into the wood?
I live on former river bottom (we're now separated by a levee). I've got pressure-treated 4x4s in the ground that have been there for 20 years now, held in by pea gravel. No concrete whatsoever. The water table rises and falls with the river. Pour in the pea gravel, add some water, jiggle the post so the pea gravel nestles in tight, add more gravel, add more water, jiggle again. Need to remove the post, just pull it straight up, by hand even. Can't do that with concrete.
Brad S - did same in Boise, ID. 25 yrs later and fence still good. Can't pull up by hand (?) so not sure what he meant by that, but doesn't wiggle or fall over and I climbed over it last year it (200 lbs.) holds up great.Corners and gate posts in concrete.
I’m building a fence about four feet an area where I need to build a retaining wall. My uphill neighbor waters a lot and it comes into my yard. In addition, when it rains I get a lot of runoff... what’s the best option for my posts? Cement? Gravel under cement?
I provide you with perfect cannot provide you with the perfect fencepost solution for your situation. However, you might consider using some type of site drainage system to remove the water from the property and therefore reduce the amount of water that could be absorbed into any lumber.
I watch your video on how water gets into the concrete and commented it could have used solutions, well here they are, I now see you have many video's and there is no magic answer for all. I agree the water in soil will leach into the gravel, no matter it's diameter around post. I live in San Francisco bay area, super wet clay in rainy season turning to concrete adobe in summer. But anyone who has dug a hole in wet clay has watched that hole start to fill with soil. I think I'm going to use roofing tar on below ground area of my post, maybe coat them with 50/50 used motor oil / diesel fuel before that and I need concrete for support as the ground saturates and my posts are tall. Thoughts on tar? I like these "thinking man" video's Cheers
You said at the best, there are no magic solutions. All of the information I have accumulated can be found at the website. Click on the outdoors link and then on fences for more information.
I've buried plenty of wood in the ground and watched it rot within a short period of time, so totally and absolutely without a doubt disagree with your statement. If you're suggesting that some wood won't rot or might take longer to rot, then I might agree, because I haven't tested every piece of lumber on the planet.
Correct. Gravel actually can end up catching water, due to be coming the path of least resistance. It can do the exact opposite of what's intended. I think complete encapsulation in concrete would be better, but I think the two part post setting foam can potentially seal the post bottom best, since it could absorb less water.
from what i heard from the guys I got my fence post supplies from was that not to encapsulate the wood in colder areas, as it give the frost heave more hold on the post and can push the post out of the concrete over time. best bet is ethier an extra treatment or char the out side of the post
I wonder if the value of gravel is that it ensures the post is encapsulated by the concrete (provided the gravel is coarse enough). The bottom end being covered in concrete has got to be better than parts of the wood being exposed to the dirt where microbes are and where moisture can wick into the wood.
That could be, but I'm guessing the gravel has something to do with water draining away from the wood post, but this wouldn't be possible in areas where the water groundwater level is high or in areas where it rains often.
This is a computer generated drawing, but it can be done in the field or in your backyard with a concrete finishing trowel. It's not hard to do and can be done as soon as the concrete is starting to get firm enough to slope it.
wood stays strong if it is wet and stays wet and never dries, or if it is dry and stays dry. I wood gets wet, then dries, then gets wet again over and over, the wood will turn to dust.
Yes, no matter what you do water will get in at the bottom. But eventually the water will drain out. And if you have say 2” of rocks under the concrete when the water drains out the air that is left will help dry out the post. If you have heavy clay water will not drain through the clay as fast but will drain eventually. The idea is to keep the wet dirt off the bottom of the post.
I bought all my fencing from a fencing contractor and he told me if I cemented the posts in the 20yr warranty on the wood was void. He was adamant that just packing the soil around the post was adequate. My fence needs replacing now after 30 yrs but for the most part it held up fine. Live in MN so we get all the elements!
PrdPapa K that is how we install our wood fence here in NY for the most part. depending on the dirt if it is clay or a dirt that does not compact well we use a dry mix of concrete and Tamp the post until it is set
before installing, soak the bottom of your wooden posts with old Engine oil for a few days...this waterproofs the wood for many years....I also wrap (or staple) heavy duty black plastic around the part of the post that is below ground level....I concrete in position, making sure that water flows away from the timber and the top of the concrete is left squared in the same direction that the blades of the lawnmower prefer as they pass by..... I secured goal posts in this way 30 years ago and they are still in use today .....
Graham Spink that's a good idea. I think they used different type of pressure treated wood back then though. I wonder if the new wood is more prone to rot
Thank you!! It’s about time someone says it right! I am a fence contractor in Oregon and get this question all the time. I have never put gravel in the bottom of my post holes!
@Fox Trot check your local code for “min frost line depth” here it is 12”. a lot of areas north can run as deep at 36”. This essentially means That during the winter months the ground can freeze and push your post up, this doesn’t happen in a single season it happens over years. If you were worried about your posts and or your frost line moving make sure you dig the bottom of the hole wider than the top of the hole and make sure it is at least a few inches below the frost line. This is typical building practice for large structures built on footings. Hope that answers your question. 👍
You're definitely correct that in fast draining soil or water holding clay, water will "wick" to and/or be drawn to and be retained in your post hole, #6 crushed stone under it or not. Similarly, concrete is highly absorbent and retentive of water. That you can't change. However, if you're building a deck that may hold a mass of people you need to over engineer it as many wood supported decks can AND DO collapse, especially those whose 2" by 12" decking is used as essentially 3rd and 4th support legs by being tied into the house flooring through the other wall of the house (a recipe for disaster). If you have found your dream home for forever or plan to live there for more than a decade I would use 4 six-inch square metal posts, all cross braced in welded flat heavy metal "x's", depending on your decks height in one or two cross braces between posts and weld cap plates at the bottom of the posts holes to slow rust. Not only do you not have to worry about what might be happening to the out of sight underground wooden braces but the only upkeep is paintng the metal support system once a year and using preservative on the wood deck. You can sleep tight at night. Also, when it comes time to sell the house the deck wouldn't lose you money but rather increase the value & asking price of the home. Make sure you invest in high quality concrete, not just use cement with no aggregate (stone) in it. Give all metal 2 layers of primer and then a third layer of your chosen color paint. More effort for sure but you only have to tend to it once a year and the only thing to need replacing will be the horizontal deck wood (use pressure treated lumber). Easy-Peesy!
When I used to do decks and fences in damp locations I would get roof cement and mineral spirits to thin and paint the bottoms of post never had any rot.
Whether the gravel retains water depends on the type of flow within the soil. If the soil is fine grained with smaller pores than the gravel and you have unsaturated flow, water will not enter the gravel because the water potential is much lower in the surrounding soil than within the gravel pores. If you have saturated flow and the soil is fully saturated around the gravel then it will move in but will then be pulled out again once you enter unsaturated conditions. Water always moves from high to low potential (the least resistance jargon largely comes into play under saturated conditions outside of soil.
Yes, I don't think gravel retaining water is going to be the big problem here, it's going to be when water from surrounding areas finds its way to any spots where it can accumulate.
I imagined that gravel was meant for a sturdy base that the concrete can penetrate into into when pouring in order to prevent the post from being exposed at the bottom, otherwise how are you supposed to set the post level and sturdy without some sort of "base plug"?
@ 6:47, absolutely. I worked in Fargo, ND, where they have clay soil and when we dug around the foundation footings to put in drain tile, or tubing, we covered it with pea rock, and the same thing on the inside around the footings, under the concrete floor, the purpose being as the path for water to travel to the sump basket, so yes that will be the path for water to go, to the gravel, which is at the bottom of the hole for the post, when in clay soil which holds water.
I would try to find out what other people in your area are using and actually having good results with. My personal opinion is that gravel might make it easier to repair your fence when it is blown over by strong winds, but concrete could provide you with a little more structural strength to keep it from blowing over or out of the ground. Please keep in mind that I don't have much experience with this problem.
I used only pea tamped for a fence built in expansive soil. I inspected the fence and posts after 12 years and the fence is like I left it , posts in good condition.
The gravel is a waste of time and materials! How do you keep the gravel, separate from the concrete? When you pour concrete over the gravel the thinner liquid will migrate to the gravel, making weak concrete of the gravel! Also the binding cement strength that has wicked into the gravel has left the remaining concrete around the Post compromised. How do you keep the two separate from each other? I can just imagine trying to attach a bladder/seal to a sonotube, then installing the post and concrete without rupturing the seal!
Where high water table causes the rot problem then you might want to coat the underground portion of the post with tar to isolate the post from standing water or moisture to keep the post dryer. Moist soil can also create a rot problem that can be reduced by surrounding the post with gravel. Moist soil has higher surface tension than gravel, so as the water table declines or dries out a gravel filled post will be dryer than the surrounding soil---this is particularly true where the soil is clay. If the post is encased in concrete which is less porous than the adjacent soil, the concrete will wick moisture to the post. You can test these situations out in a glass aquarium. Put soil in the aquarium, dig the post hole up against the glass side of the aquarium and fill it with gravel or sand, then place a drip emitter on the surface of the soil in the aquarium and take time lapse photography of the plume of saturation. You will see that a gradient forms around the gravel and the gravel is slower to saturate than the soil around it; demonstrating that the soil's smaller finer particles wick the moister away from the courser sand and gravel, until the soil can wick no more moisture and then the gravel will saturate. Alternatively, you could place the emitter in the gravel around the post and repeat the experiment to observe the soil's ability to wick water out of the gravel and up into the surrounding soil---by a property know as surface tension of water.
In my opinion it will create a water trap for any moisture that eventually absorbs into the wood post and works its way down, to eventually rot the wood.
Kutulue That's an interesting idea but rust resistant stainless steel of high quality/chromium content is expensive and still requires occasional maintenance. That would not be possible if it were buried underground. (Unless you came up with a design that somehow made it accessible or easily removed and reinstalled!) If cost is not a factor it would be interesting to give it a try though. Somebody may have already for all I know. Titanium might be an even better choice because when it oxidizes a film of titanium oxide forms on its surface that actually makes it nearly invulnerable to further corrosion. They use it to make dive knives. How about carbon fiber? Many possibilities. Personally I have to consider the cost, which limits me to 4×4 or 6×6 wood posts. Then after having watched this video I'd be prone to choose my installation method based on the type of soil.
i have watched a million videos about posts and finally, next weekend mine are going in. I plan to use the old fashioned method of prepping the post with motor oil, then dry method concrete. Just dizzy with opinions lol
@@MsLibrazen I understand and hope everything works out. I've never tried this method myself, therefore wouldn't be able to provide you with any guarantees to whether or not it would work. That's why I was suggesting to build the fence to accommodate possible future repairs.
It's difficult to explain. Soil with more clay sticks together and with less clay and more sand falls apart. Grab a handful of soil and squeeze it together and soil with more clay should form something firm.
One problem that concrete around a post has it that even when it is sloped away from the post, the concrete does not commonly adhere to the post. Water running down the post's exterior will see some moisture wick in between the post and concrete. You can't stop that permanently. The gravel does stabilize the post base though, letting me install it and setting it vertically easier, by working it around. The gravel fragments, but resists moving against other fragments. Gravel drains more readily than sand, and sand more readily than clay. In the 19th century foundation trenches were dug deeper than needed for the brick or stone to be used. Sand was bedded into the foundation trench and then leveled. In Northern California redwood planks (2xs) would then be laid down as sills and leveled on the sand bed. The brick foundation was then laid on those wooden sills. This construction lasted very well, even in Sacramento, which notoriously flooded often until adequate flood defenses were finally built. This design is still found when renovating occasionally.
35 years experience in building decks/docks porches, I concreated one set of porch post in that was the first and last time after then I poured a pillar with a 16x16 box form on top drove rebar in the center then in the 4 corners tied in a couple of other pieces and set the post on top with the main piece of rebar sticking up 4 inches in the center and drilling the post to sit over it never had a problem sense, !
Not sure where you have seen standing water mate, Ive dug posts in several different types of terrain over the years and have yet to see standing water at depths where the bottom of a post will reside.
thank you for making this kind of informative video. I know little to nothing about home improvement, DIY, or construction. I need to construct a privacy fence and remodel some old rotted fencing on a family members' property and your video is one in a series i will view in an attempt to make my outing as a amateur construction worker a solid build.
Fence posts should be first treated to at least above the ground level with copper green (dilute copper napthenate in solvent) and then painted with roofing tar (liquid rather than paste), again above the ground level. The concrete footing should also be above the ground level (but lower than the treatment) and sloped away from the post. this protects the base of the fence post against insect/termite attack as well as water-induced rot. When this is not done, fence posts inevitably fail at the ground level.
Well, with that reasoning, then why not use a circular plastic or other material form, then put that inside the hole, and put the post and fill with concrete? I'm sure there is some material that is impervious to water that can be used; of course, it will need to be flexible to a certain extent. -----Also, I would think that all the fence pros out there know how to build a fence that will last 20 years or more. There seems to be no consistent answers about exactly the best way to set fence posts. In Philly, even some fence companies put chain link fence posts about 24" into the soil, while some others say to go a minimum 36" to get under the frost line.but at 36", at least in Philly, one runs the risk of drilling into water lines, etc. Call 811 before digging to try and prevent this. ---Going 36" seems to make sense to prevent frozen water in the soil from expanding up and pushing up the entire fence post-concrete combo. Word is that if it goes 36"+, tapered hole, and filled with concrete, then the concrete below the frost line will hold the post in the ground, below the frozen section. --I'm no fence guy; I only know what I've been reading and people have been telling me. When I had an estimate done for my house, they said posts will go 22" down, and when asked about frost heaving, they just looked at me and just repeated "22 inches." What? So, I'm guessing that maybe they know the fence will not last as long as otherwise, if the posts go only 22" down, which makes more business for them
If you're going to use concrete, you will have best results by pouring the concrete in a hole to a level above ground level & install a corrosion resistant "pocket" metal bracket. The post will be suspended above concrete & surrounding soil. You can adjust the length of your post for perfect fit at time of installation. You also can simply remove it or replace it any time. Alternatively if your post has begun to rot out at ground level, you can save it (by cutting off at several inches above soil) removing it, dig a hole (removing the rotted out part) & pouring the concrete to the level to secure the bracket & post in place. The posts are usually sound, up from a few inches above ground level & worth the effort to reuse.
i've been working on a retaining wall in my backyard these last couple of weeks, 4" x 4" 1.8m total height. ultimately i decided on a gravel base with 2 engineering bricks, encased in cement for the posts. once set, i added more cement to the sides of the posts at ground level and tapered down, creating a small run-off, so no water would gather around the posts at ground level. where i live, (sunny England) i have a clay/peat cocktail for a garden. with this in mind i chose to place DPC (Damp Proof Coarse) and a 'french drain' behind this retaining wall and backfill with aggregate. all pressure treated C16 timber posts used. watched this video some weeks ago and it helped steer my decision making process. many thanks. :D
The idea behind using gravel is that when the water level goes down, the gravel will dry out quickly, whereas soil will retain moisture. If your groundwater level is above the base of your post, there is nothing that is going to stop it from getting wet other than a membrane. The only thing you can do when wood is in the ground is ensure that what surrounds the post dries out as fast as possible once the water level goes down. Bacteria needs moisture to work on the wood. Also, water doesn't always follow the path of least resistance, that is an electrical principle. Consider capillary action. When you stick a dry towel in water, it will wick the water upwards against gravity, which is not the path of least resistance. Soil also has capillary properties. Not trying to argue, just adding to the conversation. Thanks.
I only know my personal experience with "cracking clay" in Dallas. Notorious for cracking foundations. I've been at this house for 30 years & every post I've replaced the only one's that had no rot below the soil were entirely encapsulated in concrete. I'm not saying anything about the gravel approach. I'd have to see 1st hand. There is enough confirmation bias in the world creating willful ignorance. No need in me adding to it. Lol
You got me to thinking. Does the gravel approach leave the bottom exposed or not? I'm guessing it does.
@@iceebalboa3177 I'm guessing the "cracking clay" you are referring to is some sort of expansive clay, which means it expands when it's wet and thus will flex and break a foundation. Here in Mississippi, we have "blue clay" which is expansive and "red clay" which is basically a blend of sand, clay and minerals that packs hard and doesn't expand much when wet. As far as your question goes on the gravel approach leaving the bottom of the post exposed, basically, you put several inches of gravel in the bottom of the hole, then place the post, then fill the hole surrounding the post with more gravel. Rain fills the hole at which point the surrounding soil wicks the water from the gravel filled hole through capillary action providing the soil type has such properties. Again, this is the idea behind it. I haven't done vigorous experiments, so I too will digress from adding to the confirmation bias.
@@johndoby It's just really bad down here. Heck, I'm originally from Hays,Kansas but even after moving to TX at 10 I have no choice but to be a nonconformist. I have varying views, so not only am I often automatically dismissed, I once had white folks talking down to me so bad I began wondering how I'd feel if I wasn't white. Dallas is my 6th city & been in this mess since I was 16. I can't do phoney & most people who move here conform or don't draw out all the arrogance from people the way I do. It's funny I'm always smiling & people tell me I lift them up. I like people. Sometimes I wonder if they don't like that I do. Their confirmation bias probably plays a part in why I always put myself in other people's shoes. I could write a book on these people. The entire world would believe it, except for a Dallas native. They'd say I was jealous & believe it because they flatter themselves that way. The older I get the more toxic this environment becomes
I've dug up wood that was used as shoring near the Delaware River, the wood was put there throughout the 1800's, it is always in pristine condition when digging to repair the sewers.
Good common sense point
I am amazed that there are so many knowledgeable people here with so many years of experience with wood posts in the ground, yet no one seems aware of the fact that if a french drain were added into the picture, it would barely matter which method one uses for planting their wood posts. Have you ever heard of a post rotting when the structure had a perimeter french drain? As for fence posts- no, one would not bother to put a drain, but sleeving them would do just fine. Nowadays, sleeving is so cheap and easy to do. Whether with just motor oil and diesel, or PE wrap. No muss, no fuss. I know of spruce posts (yes, spruce) that are sleeved and good for some twenty years so far and going great.
After gardening for 30 years, I suggest keeping soil away from wood posts. Soil is the fastest way to rot because it gives soil-borne bugs, fungus, and bacteria a direct path to eat the wood. Using a gravel layer on the bottom helps slow them down and allows excess water to drain out (in most reasonable draining soils). If you have long-standing pooling of water, consider tar or other waterproofing but don't let the soil touch the wood.
yes and no, pressure treated wood can last decades in dirt
Thanks for sharing! I'm experimenting using char instead of gravel, hoping that wood eating bacteria won't like this environment. Any bets?
@@aldoconciso I have seen people burn the outer layer of the wood with fire or a torch. Insects don't like it as much and it is semi-waterproof. I just did that for some 6x6 steps and laid them on a layer of gravel.
@@bibleboardgames i've also tried burning them a bit on a bonfire. Still standing, but it's time consuming if you have many posts to treat. I'll try smoking a batch with a torch, thanks!
@@bibleboardgames
You would want to be pretty careful doing that with treated wood, you'll be getting a lung full off arsenic.
My method for a standard 6’ high fence in heavy clay: drill hole 8” diameter / 30” deep with auger; insert 8” diameter cardboard form leaving about 1/2” of form above final grade; fill any unevenness between form sides and hole with loose, dry soil mixed 50/50 with coarse sand, then water in; place 6” of crushed medium granite in hole and firmly tamp; coat bottom 25” of post including base surface with asphalt roof sealant; center post in hole; fill around post with same medium crushed granite, tamping firmly as you go, stopping 6” from top of tube; fill remainder of tube with Quikcrete and slope surface so about 1/4” of the asphalt shows.
A couple notes: 1) Water does not flow in wood. It wicks thru capillary action until saturated and gravity has little effect on this wicking. By sealing the post with asphalt below-grade, the only way for water to saturate the post at and just below grade (where rot is most likely) is for it to be wicked in from above-grade. The asphalt coating will not act as a cup for water accumulation - as the post dries any moisture will be wicked up and out. If you asphalt seal below-grade, and stain above-grade, very little moisture will find its way into the crucial rot zone. Without excessive moisture there will little in microbes or fungus and thus no rot. 2) The 6” Quikcrete cap acts like a lid to prevent the hole from filling with runoff. Any moisture that finds its way between the Quikcrete cap and the asphalt-coated post has nowhere to go but down into the gravel. If you really want to be thorough you can fill any gap that eventually forms between post and concrete with tube asphalt and a caulk gun. You can also use concrete sealant on the cap, and since it is not driven or walked on this sealant will last a very long time. The cap will not heave since there is 24” of crushed granite under it.
I'd heard the gravel idea. In a lot of the UK we have heavy clay, and the inherant slow draining, but the water table is often several feet or even several yards down. We tend to have steady rain rather than heavy rain (though this might be changing) and so, while the ground is often soaked, it isn't actually flooded with water. So, if you dig a 2' depth hole in the ground and keep it covered, the hole does not fill up with water.
This being the case, I think, in these conditions, gravel would not cause a problem even in clay, and since there are no fines in the gravel, the water would not be able to soak into the gravel as the gaps between the stones prevent caplilliary attraction: any water would drip to the bottom of the gravel pit, not soak to the top.
The advantage as I see it is that small quantities of water that may be able to get in between the post and the concrete are not forced to wait to be absorbed by the timber or the concrete - they can simply drip down through the gravel (emphasis being on the quantities being small, otherwise, as you say, the gravel just fills with water.
But obviously, as you say, soil varies immensely from place to place, and that's what I am taking from your video. You've made me think. Thank you!
You always have interesting comments and provide us with a different perspective of how things are done in the United Kingdom and they are always appreciated. Thanks for watching and taking the time to share interesting stories, when you would probably rather be at the pub.
:)
put gravel as deep as the water level in the summer. if it means 3m deep then is it 3m deep. But you never have wet fencepostes.
Interesting you say that about the rain. Seattle is being the same way. I am used to a much more steady low rate rain. We have been getting heavy rain, what seems like, a lot more. And then a lot more dry in the summer.
Having been in forestry and sawmilling in the UK for over thirty years. I can assure you most posts will rot faster in concrete. Especially oak.
Oxygen and damp is the perfect environment for rotting so above ground drys or seasons and deep down waterlogged wood with no oxygen is unaffected.
We used to ram the posts in with layers of soil then small stones a few inches at a time.
The old estates used to air dry their fence posts for years before using them and would often tar and charr the bottoms. Just the charring makes a big difference.
Got a kids play-set from a man giving it away 10+ years ago and cemented the 4x4 posts in the ground. This weekend I dug them up to give to a friend with children. 6 of the 8 posts looked absolutely perfect. 1 post had some decay and another had quite a bit as well. Honestly I think it depends on the wood itself and maybe how well the concrete forms around the post.
If you keep wood either dry, or wet; it will last indefinitely. What destroys wood, is the wet dry cycle. When it is moist, it is attacked by carpenter ants and termites. When it dries, the fibers become distorted, and they break under tension, accelerated by dirt replacing the water. There is more empty distance between the fibers where the water used to be. If you put a post in just gravel, it will last longer than one in concrete. As noted, concrete is porous, and it holds water longer than gravel alone.
You would think, at this point, that we could actually have *data* on what works best in what climates. All we get is a bunch of videos and comments with "I always do it this way and it works".
I agree, but I don't think there is a way to prevent the wood from rotting without using pressure-treated lumber design specifically to be buried in the ground or have contact with concrete that is buried in the ground. In other words, I haven't came across a cost effective method that works or one that works in different parts of the world.
@@gregvancom I paint the bottoms and sides of the posts up to three feet with roll on bed liner material I just began doing this and I expect the material will prevent rot under the painted areas long after I die.
First off, how old are you? If you're 85 years old, then your prediction might be correct, but if you're 20 years old, you will have to let us know what happens in the future. :)
HAHAHAHA!!!!!!!! Reminds me of recipe reviews where they add or subtract a bunch of ingredients and then say it sucked!
How can the bed liner material even adhere to a very wet freshly treated post?
thank you. I have clay soil and encased the entire bottom of the 4x4 due to this videos help // no rock drainge here // cheers
Glad it helped
I use gravel no matter what soil. 1st is help stabilize the post in all direction. 2nd it help grade the post. I also pour concrete on the top of the gravel to seal the bottom of the post. then pour the rest of the hole for strenght
Concrete is permeable, not waterproof. It will not "seal" the bottom of the post.
@@spatt833 then what is the purpose of concrete?
You're making much sense Greg and your point gets across. Physics rules and you're going by that, even if you might not explicitly mention it. I've been thinking for a while about the issues presented here, as we've got a very heavy clay soil in our property, and realized couldn't take a "one size fits all" approach. The type of soil one got matters a lot. Thank you for sharing your ideas and experience
You're very welcome and thanks for the kind words.
I would never encapsulate the wood in concrete. I have posts I did 22 years ago which I did with gravel at the bottom and they are still going strong. I angled the concrete like you said as well. However the pressure treated 4x4s have shrunk over the years (1/8th inch maybe on each side) so there is a small gap around the perimeter of the wood/concrete where water definitely would go into the bottom of an enclosed encapsulated concrete base versus draining as it does now with gravel. I live in Texas gulf coast. I see your point about standing water but I don't think I have standing water as you illustrated for very prolonged periods of time. Hence I am going with the gravel approach when I have to do it again based on 22 years of success in my case. Encapsulated might be ok if you could seal the wood shrinkage issue and keep water from flowing down into the enclosed pocket. Thanks for video. Interesting discussion for sure
you can fill up the gap between the wood and the concrete with some silicones ( not the stiff ones) , the ones used by carpenters/windowmakers to fix the glass in windows and doors for example
I don't know why the RUclips algorithm brought me here, but now I'm learning about gravel at the bottom of a weed fence post.
I dug a 2 foot deep hole today for a mailbox post that is 6x6, 5 inches of topsoil and then clay down to the 2 foot depth. At first there was no water but after 30 minutes there was 1/2 of water at the bottom. Setting the post tomorrow, will be interesting to see how much water is in the hole when I'm ready to set the post. It may be completely full we will see. Any thoughts on painting the wood with a thick coat of silicon? I did paint the post with 3 coats of exterior paint. I did use ground contact wood. I was going to use gravel but I see this is probably not a good idea.
If you have a lot of water in soil, then maybe a metal post or masonry will work better.
Kind of depends on the type of gravel too there's a lot of variables here. Three-quarter or 5/8 with fines packs really well probably won't hold much water especially when compacted. It makes sense to put 5/8 or 3/4 crushed rock with fines at the bottom of the hole because it is not dirt which has bacteria in it that attacks wood. Here in the Pacific Northwest dirt generally retains more water. The biggest issue I've seen is when vegetation / bark dirt grass, dead grass collects against the bottom of the fence post for years and has a tendency to collect the rain and soak the bottom of the post and that creates a rot situation.
It is a sandy loan. Water is about 15 feet down. 14" of rain per year. Central Valley of CA. So temps are 28 to 110F
I feel good that you report what I had guessed would happen - water pooling in the gravel.
It's simple. Whatever is heavier displaces what's lighter. Gravel has lots of air....which gets displaced by water - instead of dirt. Yikes!!!
Thanks. This was just an thought thing for me.
Thanks for sharing
Here in Canada the biggest problem is most often frost heaving the forms and carrying the post along...among other precautions I'm told gravel well placed, reduces the ability of freezing soils to get a hold on the concrete...As far as moisture, I know one guy who tars then wraps wooden posts in garbage bags, then concretes them in. I'm curious what you think about this idea? I've never gone to check back over time how this method stands up.
I agree, the frost is the biggest problem here. In my area I have to go at least 6ft down to be under the frostline and build the base wider then the concrete column to keep them from moving.
I don't see why tar and plastic bag wouldn't work. Sounds like it would seal up nice and protect the post from beeing soaked in water.
The main benefit of using gravel in post holes in low-lying areas isn't for drainage at all; it's to help lock the post in place. It's much more difficult for the post to start leaning when it's surrounded by gravel than it is when it's surrounded by wet soil.
I am building a pool deck and was thinking about sealing the posts with liquid rubber. Thoughts?
I'm wondering if that would cause the post to retain water if it entered from on top, but sounds like you will have a roof over it. Might get some sideways rain or splashing but hopefully not enough to saturate the wood.
Mark post 6” above ground and tape round that line and bitumen paint the whole bottom of the post, let dry then concrete. They rot above the ground where air and moisture get in. Had posts in 20 years and no rot yet. Always put a top cap on the post to stop water getting in the end grain.
I've never used gravel below one-off posts for mailboxes or retractable hoses, etc. I've shovel-dug the holes, set about 1/3rd of the post into the hole, then filled with fast-setting Quikrete then soaked the whole area with a garden hose. Cedar 4x4's have always worked best for this type of one-off installation. Cedar can take decades to rot even if it's continually exposed to water. My mailbox post has remained level and solid for over 7 years, despite the freeze/thaw cycles and harsh winters we have in Western NY. For decks/fences and other wooden structures that need to remain level with proper drainage, I would opt to use a few inches of gravel below those posts, primarily for leveling purposes. Overall I would agree that the gravel probably doesn't do too much if anything to "drain" water especially in heavy-clay soils, which is what I have in my area (the entire NE US is mostly clay soils). Doubtful that a few inches of gravel would prevent decay from water exposure, unless you live in an area with a dry climate and sandy/gravel-filled soils...and I wouldn't bother with gravel if my soil was sandy. I've pulled cedar posts that were in the ground for 15-20 years and I have yet to see one with substantial rot.
used stripped cedar post with no concrete for fence post. 25 years later still doing its job. Also, concreted corner support cedar post. Couldn't speak for use as supporting beams.
What you don't want is the wood getting wet and drying out many times. In the graphic shown in the video, the best way to do it is wrap the portion of the post that is encased in concrete with a moisture barrier like roofing felt.
I don’t think it is for standing water. It just speeds up the drainage in case of water coming from above (rain). It doesn’t solve the problem, but it shortens the time when it is wet, adding a few years to its lifetime for cheap.
Forget the concrete. Put some gravel in the hole, put the column in and the place gravel around post and compact as much as possible in lifts. The more the post wiggles the tighter the gravel gets. For extra protection coat the part of the post going in the ground with an asphaltic foundation coating.Keep in mind if you cut the post you lose your pressure treatment so the cut part of the poss has to be field dressed with a preservation sealer. The wood should never be in contact with the soil on the end grain.
My experience was just the opposite re: the base (with a clay soil), but the sloped top of the concrete is crucial. I replaced our fence a couple years ago and the concrete at the top was not really well placed. It looked as though it has been just shoveled into the hole around the post below grade and almost funnel-shaped. The wood at the top of the concrete was rotten; the fence was falling over. But when I dug up the post base pieces, the wood sticking out under the concrete was fine! I think that the clay soil fills the gap soon after the post is placed and that blocks moisture from moving into the space around the post base. Remember, even with clay soil moving water will carry that soil into the voids (whether it’s gravel or just loose soil.
Like he said wood needs air to rot. Air can move through concrete. best to keep concrete covered with clay. but dont let posts be a low spot to pond water around.
I think in most cases your better off coating the pressure treated post with used engine oil or tar about an inch above ground to the bottom. Then just foot it in gravel and then layer the gravel and soil up the post every few inches. Then it keeps it stable, no freezing/heaving problems and everything drains and pulls moisture from the post. If you have to just pour concrete at the bottom to keep it from moving in sandy soils.
I'm starting to agree with the idea that gravel might be better in areas where water freezes and forces the fence posts out of the ground.
I removed two posts today. One had rotted at the top where it was inserted into concrete, due to the soil around it. The other was not rotten, but was softest at the base. I suspect it is often more important to ensure concrete extends above the soil level.
I installed fences 35+ years ago with gravel and they are still standing. The wood acts as a wick so I put 6 inches to 12 inches of rock. I do the same thing in planting in pots. I put an inch of rocks so they don't get root rot. Many old timers use diesel and oil mixture to soak the ends as well.
does that diesel/oil mixture work good? what are other good alternatives to coating the ends and is it advised to coat the ends to begin with?
The solution I have found when installing wood posts in damp soil is to dig a trench and install 3" wrapped flexible corrugated perforated drain pipe 1-2 feet away from the posts and parallel to the post line. Lay the pipe about 4" deeper than the post bottom and run it out out to daylight (I have a gulley) on a drain grade (-1/4" in 10'). Put 6" clean gravel under the post footing and over to the drain pipe. Lay some filter fabric over the gravel or wrap it to keep the dirt out. Or you could run the drain pipes to a dry well and pump out the water. I have sandy soil and my treated posts still rot off at ground level unless the concrete comes up above ground. I rented a trencher machine for a day and retrofitted 4 pole barns and and several hundred feet of wood fence with drain pipes in 2 days by myself. Way cheaper than jacking up a building and replacing the rotten post bottoms.
Could you pour the concrete into a contractor grade plastic bag. Wouldn't that keep or slow down the water getting into the concrete. And also pretreat the wood post. with 50/50 oil/kero.
I don't like the idea of the concrete bag, but treating the wood post sounds like a good idea.
In Australia it’s all about termite protection for timber in the ground. Treated pine or treated eucalyptus species for power poles.
Does the eucalyptus work better, it seems like it's a harder wood or more dense?
@@gregvancom eucalyptus is a strong timber, however timber density is no deterrent for our termites or fungal attack in Australia, if untreated in the ground.
Australian turpentine hardwood is use in marine environments for wharf piles around the world. Another Australian species “cypress pine” is termite proof, dense and used for flooring.
Great info,, was about to say a lot has to do with the soil, weather conditions....etc, pre treatment of timber,, I always put extra on my sub level and never had issues
Been researching this for years - when building decks and fences, etc... I"m building a log building and I'm using 10-12" log posts and I'm thinking I'm going to copper coat them, then put them in about a foot of concrete at the bottom, then dirt for 2 1/2'. Every few years I'm just going to dig around them about 1-2' deep re coat. I guess the absolute safest method would be brackets on top of concrete, but those are expensive and I kinda don't trust brackets for a building in regards to lateral movement..
I'm not 100% sure what you doing, can you provide me with more details or email me some pictures. Keep in mind that I am not a structural engineer and will only be able to provide you with an opinion.
@@gregvancom . Copper coat from Home Depot helps with fungus and bugs and rot. I had planned to coat them with that and then maybe Liquid Rubber, since they will be covered and rain water won't get between the wood and the coating. Instead of fully encasing them in concrete, I was thinking about a donut of concrete toward the bottom just to stabilize. I was thinking of recoating them about a foot deep, with rubber or copper, every 5 years or so, even though I might not need to since they are under a roof and the soil is clay like. Hope that makes sense. The plan is still evolving.
I use treated wood if i put a post in the ground. I have 2 six by sixes for my gate. They are treated wood and have been there for almost 30 years.
Interesting and informative video with lots of great comments.
From my perspective, the only way gravel would be effective for very wet environments, is to widely excavate the entire fence line and back fill it with gravel. Then, add a drainage system to the lowest portion of the gravel bed. A pipe with holes drilled into the top edge comes to mind (perforated drainage pipe with holes facing upwards and sideways). The perforated drainage pipe would need to be plumbed into non perforated drainage pipe pipes on the low side of the fence line. The wetter the soil, the more drainage pipes (possibly using T connections) leading to low elevation would be required to move water away from the fence posts along the entire fence line.
I would probably seal the bottom foot or two of each post with a heavy-duty watertight membrane similar to what is used in shower deck installations. Lastly, I may even consider covering the gravel with an inch or so of concrete to help minimize moisture hydraulically penetrating the gravel if or when the water table rises to the topmost area of the gravel.
Again, this is just what I would consider doing if working in moisture challenging environment.
To be sure, I am no hydrologist, not a trained fence builder or contractor, and probably have no business even suggesting what I would do. The topic was interesting, and I believe everyone's perspective can be useful.
Mark Nicholson (Retired)
Former, US Army - EFMB,
Combat Medical Specialist
1/94 FA MLRS - Erlangen West Germany
690th, Medical Company supporting
Misc. Weapons Ranges, Airborne Jump School
and Ranger Training Brigade (ARTB) - Ft. Benning Georgia
What’s your recommendation for a fence post that does have a high water table? Currently that is my situation. Install metal poles under frost line? Install helical metal posts?
This isn't an easy question to answer, but I would probably go with metal. However, drive around your area and see what others might be using to see if something else is working better.
I feel like if your local water table is that high, maybe consider a solid cement pier with the wood attached on top or go with vinyl fence posts. I don’t think I’d ever build a wooden fence that I know is going to be constantly submerged.
From my experience, unless your yard is desert-like, I don't think you should use concrete with wooden posts. They rot too quickly when parts of the post are in concrete. Concrete is for steel posts . If you worry that the fenceline wooden posts will lean, use bigger, longer posts, and tamp them well. If you're worried about corner posts, make them bigger and longer, and cross brace them to adjacent posts or struts. I think it helps to use the wooden posts with creosote bottoms. The creosote should reach above ground level. I think it helps to mound the soil around the base of the post to avoid puddling water. In my area, heaving is not a big problem unless the posts are shallow, and the concrete is also shallow. We tend to have clay below 12". We're semi-arid with Winter temps rarely below -10.
Great points and thanks for sharing your experience with us.
I think it's better (and a lot easier/faster) to drive them in. A backhoe bucket full of dirt or gravel can push a 6" sharpened round fence post in pretty well. A little tap-tap-tap is sometimes required. They will be tighter than most people tamp them in. Haven't done square posts, but should work just as well.
That sounds good, but you would need a backhoe and someone like yourself who could push them in straight enough to create a nice looking fence. Sounds like digging a hole might be better for me.
I've done it that way on some soft soil. We mounted a chain on the bucket in such way that you could judged where plumb was from the cab of the tractor. You either want the posts cut straight across, or have them sharpened to a 4 sided point. Wedge points tended to drive crooked. Chisel points go very crooked.
It's kind of a 2 person job. Not too difficult to push them in pretty straight, maybe not plumb-bob straight, but pretty straight.
Lots of rock in my area so I put the post on a rock at bottom of hole. Then add concrete. Rock may help keep moisture off post. Used this procedure and privacy fence is still standing after 30 years.
I have just replaced a fence post at the weekend and it had no gravel at the bottom. Do you know what section of the post was most rotten? The part that was at ground level. The base of the post and about 10 inches above that was in significantly better condition.
The base of the post was not treated to any preservatives.
In conclusion, adding gravel or any other substrate to the bottom of the hole is largely a waste of time.
For posts can't I use tar on ends and four sides to.prevent rot?
Excellent video - an even more practical point. Either set up - a cemented post ( nice cap design!) will outlive most of us.
I have several full 4x4 pressure treated post that have rotted at the top of the concrete piling, where the post meets the concrete. When I pulled out the piling the bottom of the post was like brand new, no rot at all, solid. Gravel was not used in the bottom of the hole, direct contact with the soil. It was clay soil also. These post have been in the ground for at least 35 years. Can’t explain it. Anyone know how to get a slop concrete top using Quikrete?
For rot to start you need three things, moisture, air and the microbes that attack the wood these three come together at or just below ground level. Putting gravel in the bottom of the hole makes a void for water to collect but if there is little or no air down there them the water will do little harm or even any good.
Your absolutely right. After seven years or so my posts are rotting from 5 “or 6” underground . Everything deeper or above is fine. Painting the new posts with copper napthate then tarring them. We’ll see how they do if I live long enough.
@@craigkeller Every time a post gives way at or just below ground level dig out the stump and while it might not be on good condition it will be far better than the point of rot.
@@craigkeller Thank you, there has been so much ROT talked about posts rotting. IT IS THE FEW INCHES ABOVE AND BELOW GROUND THAT ROT FIRST. Someone suggested wrapping felt round the post but unless you can make an air/water tight seal (virtually impossible)at the top of the felt it will let moisture in between post and felt, the same with concrete, post shrinks and swells and lets moisture in. One tip I heard many years ago is to drill a hole 1/2 ins or so at 45 degrees from just above ground level to just below and about 3/4 the way through. Fill this hole with preservative and plug with a removable cork then every year or so go with an oil can and squirt the hole full of preservative.
I have a theory: What if we set the bottom of the post in 6" of concrete at lets say 4' down and in the centre of a 1 squarefoot area.. Then, we trench around the perimeter of that 1 squarefoot area 6 inches deeper than the bottom of the concrete, so a 4.5 foot deep drench.. We then fill the bottom of the trench with 6" of gravel making the path of least resistance below the bottom of the concrete/post... and then backfill the trench with dirt and place sod.. Just like we do for drainage systems around residential footings.. What do you think @gregvancom ?
That sounds like a lot of work, but definitely something that will allow water to drain into the gravel easier than it might in other soils, especially clay. However, it might not work as well in areas with higher water tables or in areas or the soil retains water for longer periods of time. The gravel can actually form water collecting pools and make the situation worse.
@@gregvancom Thank you for the response!! I live in ontario where the frost level is at 4' so all concrete footings need to be below the frost line. I'm a first time homeowner and your videos have helped me tremendously when it comes to understanding building construction and making the best possible decision for laying out my projects. I have an old 1940s cape cod style home with 4 exterior walls resting on concrete footings and a 18" crawlspace with a centre support beam spanning the length of the home, The home is split down the middle with a wall directly over the crawlspace beam.. On the left half of the home it is completely open from front exterior to back exterior wall.. It has a knee-wall attic and I would like to vault 1/2 of the ceiling of the left side of the home (1/4 of the homes entire ceiling) (15' x 11.5') to make a balcony loft/mezzanine .. So far I have sistered on 2x6 exterior walls and 2x10 floor and ceiling joists.. My plan was to install a 4"x12" beam from the exterior wall to the center wall (11.5') and then install another beam lengthwise (15') connecting the 4"x12" beam to the exterior wall in order to support the roof rafters.. Would this be sufficient or would additional support be needed to handle the live load of a mezzanine? would you be able to make a video if I sent you a rough blueprint drawing?
@@auntjemima5120 You're welcome. It sounds like you need engineering advice and I cannot provide that. I also don't make free videos that offer specific design information for individuals. However, I don't mind taking a look at building plans and answering other questions if you have them about building.
Don't Google it. Ask a contractor or ask your neighbor. My next door neighbor was taking a fence down after 20 years, I helped him pull up some posts that were set without concrete of any kind, but simply with pea gravel. These posts were still in perfect shape, just as good as the post above ground. So when I put my fence in, I used his exact technique. Clay soil with okay drainage, but we have the same soil, the same slope and all that, so I'm banking on the knowledge of those who came before me that my fence will do allright. I packed it tight with pea gravel and the fence is still upright and plumb after 60 mph winds coming through town.
Thanks for sharing.
Use cedar if you can, go below the frost line so it won't heave, use a string to keep the posts in a straight line so it looks good, use a heavier post to hang the gate on, and it will last for 25-30 years. Every fence needs work/replacement after that.
What if you put the wood on top of the concrete where you use hardware? Post never enters the ground/concrete? More expensive but will it lasts longer?
I agree with you. I created a gravel pad about 6 inches deep for a shed on clay soil and it filled up like a swimming pool when it rained.
Thanks for sharing your story with us and I've seen it before myself.
That method calls for an accompanying french drain!
Does it make sense to coat the bottom of the wood post in some sort of tar to repel water?
This is what I normally do, for the wood that is going to be in the ground, I give it a coating with the liquid compound you use on roofs first. then when it has dried, then place the post in the hole and fill with the desired amount of concrete. So far it has worked very well!
I live in Houston a few feet above sea level. It rains most of the year so the clay soil stays wet; dries out to a crust in the heat. It's anecdotal but I've done that for years with great success. The roofing asphalt keeps anything from wicking up the end grain and creates a barrier when that void forms as the wood shrinks back in the concrete during the dry times. My current fence set with that method is over 20years old with no rotten posts.
What brand or type would you recommend, I'm about to put up 800' of wood fence..
@@asasmith5639 Henry 201
I feel like this is probably the best way to go about using wooden posts. Seal the wood so that it cannot absorb the water and you'll have no rot. I'm also curious, if you use the old technique of burning the surface portions of your post that will be subsurface, will that also help? I know several people who build using old methods and they do this, seemingly with great success. No chemicals needed with that method.
@@t-6273 Any method that shields the wood from rot is good in my book. When I coat the bottom of the posts, I make sure the coating goes 2-3” above the surface of the ground.
I don't think the bottom matters either way because it will wick a few inches up if that's the case. But no concrete anywhere. Pack it in with dirt and gravel as you backfill. I've redone 100 year old farm fence posts that were just dirt and not that bad and I've took out 10 and 20 year old Cedar and treated posts that were rotted bad because they were covered in concrete.
At the end of the day , soft wood will only last so long outside. I dip the ends of my posts in tar or bitumen up to where the concrete will finish . let it dry off and concrete just above ground level as you've shown on this vid .
That's what my dad told me as well.
👍
What about water(Rain) getting between the post and the concrete? it has to go somewhere or it will sit an rot the post out quickly. If there is a drain at the bottom it has an exit. Also there is water in the post on new post that needs to exit or dry out too.
Small amounts of moisture might not be as big of a problem as a steady supply of rain water that takes a while to leave the area.
Wish I could show you a picture of the concrete fence post my father and I used to make. His first fence using them back in 1977, was just recently rebuilt with new lumer, but the concrete post still standing straight are still going strong.
Awesome.
im building a deck in sandy soil.. do i need gravel or cookies underneath the posts or can i just put the post in the hole and put concrete around it?
This video might help ruclips.net/video/bAmY1uThyLM/видео.html
"The perfect fence post and concrete design..." Well, almost. The corners of the posts should be radiused wherever the posts are encased in concrete (normally from the bottom of each post to about an inch above the expected concrete level). This rounding removes the sharp corners of the post (stress raisers), significantly reducing the probability of cracks forming in the concrete at those points.
Great idea!
Thanks. I’ll use a planer.
if the post is fully encapsulated in the concrete then the concrete will do the same thing the gravel will do anyway. the gravel is definitely pointless. also as you stated the dirt will make its way in to the gravel anyway and youll actually have another problem develop even if its not severe which is cavitation. how do you solve that? filter fabric but even with that itll get clogged up over time and end up retaining water more than the dirt itself would. plus im not really sure why there is so much talk about protecting the part of the post that is in the ground when ,as far as ive see, its always the last thing to rot away. the part thats in the ground always lasts longer no matter what extra step you take to prolong the inevitable. seems like a lot of effort to fix a problem that is redundant. if you are using concrete for a stable foundation then there is no reason to do anything else. if you are just driving the post in bare then the only thing you need to worry about is protecting the first 6-12 inches that is making contact with the top soil.
How did you create the domed portion of the concrete for run off? Just shape it with a trowel?
Yes, just shape it with the trowel.
So just wrap every post with Saran wrap?
Maybe the extra thick kind:)
It doesn't make any difference to me. I have clay soil and it holds water really good. I am at the bottom of a hill so water comes to me. I will say my fence has lasted seventeen years and I am at the point where I have some leaning post. I have stained and waterproofed at least 3 times and all of my neighbors fences are in worse shape than mine. One thing that helps is that I keep grass away from my fence bottom. My weed eater did cut into the wood at the bottom of the pickets so I took a laminate saw cut about an inch off the bottom of the fence to make it easier to weed eat under the fence as well. It look much better too. A note about stain. Using a dark stain on your fence looks great when you put it on but after the birds get through with it you might as well have painted it white.
Wouldnt it help if the wood post was completely sealed with something like a polyurethane sealer prior to putting the post in the ground to stop the moisture from absorbing into the wood?
I live on former river bottom (we're now separated by a levee). I've got pressure-treated 4x4s in the ground that have been there for 20 years now, held in by pea gravel. No concrete whatsoever. The water table rises and falls with the river. Pour in the pea gravel, add some water, jiggle the post so the pea gravel nestles in tight, add more gravel, add more water, jiggle again. Need to remove the post, just pull it straight up, by hand even. Can't do that with concrete.
how does it stay still?
Brad S - did same in Boise, ID. 25 yrs later and fence still good. Can't pull up by hand (?) so not sure what he meant by that, but doesn't wiggle or fall over and I climbed over it last year it (200 lbs.) holds up great.Corners and gate posts in concrete.
I’m building a fence about four feet an area where I need to build a retaining wall. My uphill neighbor waters a lot and it comes into my yard. In addition, when it rains I get a lot of runoff... what’s the best option for my posts? Cement? Gravel under cement?
I provide you with perfect cannot provide you with the perfect fencepost solution for your situation. However, you might consider using some type of site drainage system to remove the water from the property and therefore reduce the amount of water that could be absorbed into any lumber.
I watch your video on how water gets into the concrete and commented it could have used solutions, well here they are, I now see you have many video's and there is no magic answer for all.
I agree the water in soil will leach into the gravel, no matter it's diameter around post. I live in San Francisco bay area, super wet clay in rainy season turning to concrete adobe in summer. But anyone who has dug a hole in wet clay has watched that hole start to fill with soil.
I think I'm going to use roofing tar on below ground area of my post, maybe coat them with 50/50 used motor oil / diesel fuel before that and I need concrete for support as the ground saturates and my posts are tall.
Thoughts on tar?
I like these "thinking man" video's Cheers
You said at the best, there are no magic solutions. All of the information I have accumulated can be found at the website. Click on the outdoors link and then on fences for more information.
Like someone said earlier they do not rot under ground only at ground level !
I've buried plenty of wood in the ground and watched it rot within a short period of time, so totally and absolutely without a doubt disagree with your statement. If you're suggesting that some wood won't rot or might take longer to rot, then I might agree, because I haven't tested every piece of lumber on the planet.
Correct. Gravel actually can end up catching water, due to be coming the path of least resistance. It can do the exact opposite of what's intended. I think complete encapsulation in concrete would be better, but I think the two part post setting foam can potentially seal the post bottom best, since it could absorb less water.
from what i heard from the guys I got my fence post supplies from was that not to encapsulate the wood in colder areas, as it give the frost heave more hold on the post and can push the post out of the concrete over time. best bet is ethier an extra treatment or char the out side of the post
I wonder if the value of gravel is that it ensures the post is encapsulated by the concrete (provided the gravel is coarse enough). The bottom end being covered in concrete has got to be better than parts of the wood being exposed to the dirt where microbes are and where moisture can wick into the wood.
That could be, but I'm guessing the gravel has something to do with water draining away from the wood post, but this wouldn't be possible in areas where the water groundwater level is high or in areas where it rains often.
Sir; how did you make the dome shape? Are there commercial forms that do this?
This is a computer generated drawing, but it can be done in the field or in your backyard with a concrete finishing trowel. It's not hard to do and can be done as soon as the concrete is starting to get firm enough to slope it.
wood stays strong if it is wet and stays wet and never dries, or if it is dry and stays dry. I wood gets wet, then dries, then gets wet again over and over, the wood will turn to dust.
Yes, no matter what you do water will get in at the bottom. But eventually the water will drain out. And if you have say 2” of rocks under the concrete when the water drains out the air that is left will help dry out the post. If you have heavy clay water will not drain through the clay as fast but will drain eventually. The idea is to keep the wet dirt off the bottom of the post.
I bought all my fencing from a fencing contractor and he told me if I cemented the posts in the 20yr warranty on the wood was void. He was adamant that just packing the soil around the post was adequate. My fence needs replacing now after 30 yrs but for the most part it held up fine. Live in MN so we get all the elements!
PrdPapa K that is how we install our wood fence here in NY for the most part. depending on the dirt if it is clay or a dirt that does not compact well we use a dry mix of concrete and Tamp the post until it is set
before installing, soak the bottom of your wooden posts with old Engine oil for a few days...this waterproofs the wood for many years....I also wrap (or staple) heavy duty black plastic around the part of the post that is below ground level....I concrete in position, making sure that water flows away from the timber and the top of the concrete is left squared in the same direction that the blades of the lawnmower prefer as they pass by.....
I secured goal posts in this way 30 years ago and they are still in use today .....
Graham Spink that's a good idea. I think they used different type of pressure treated wood back then though. I wonder if the new wood is more prone to rot
Thank you for this piece of critical info! You are the best
My pleasure!
Thank you!! It’s about time someone says it right! I am a fence contractor in Oregon and get this question all the time. I have never put gravel in the bottom of my post holes!
Right on!
@Fox Trot check your local code for “min frost line depth” here it is 12”. a lot of areas north can run as deep at 36”. This essentially means That during the winter months the ground can freeze and push your post up, this doesn’t happen in a single season it happens over years. If you were worried about your posts and or your frost line moving make sure you dig the bottom of the hole wider than the top of the hole and make sure it is at least a few inches below the frost line. This is typical building practice for large structures built on footings. Hope that answers your question. 👍
Short answer (saving 9:58): No
The short answer is short.
@@gregvancom 🤔
You're definitely correct that in fast draining soil or water holding clay, water will "wick" to and/or be drawn to and be retained in your post hole, #6 crushed stone under it or not. Similarly, concrete is highly absorbent and retentive of water. That you can't change. However, if you're building a deck that may hold a mass of people you need to over engineer it as many wood supported decks can AND DO collapse, especially those whose 2" by 12" decking is used as essentially 3rd and 4th support legs by being tied into the house flooring through the other wall of the house (a recipe for disaster). If you have found your dream home for forever or plan to live there for more than a decade I would use 4 six-inch square metal posts, all cross braced in welded flat heavy metal "x's", depending on your decks height in one or two cross braces between posts and weld cap plates at the bottom of the posts holes to slow rust. Not only do you not have to worry about what might be happening to the out of sight underground wooden braces but the only upkeep is paintng the metal support system once a year and using preservative on the wood deck. You can sleep tight at night. Also, when it comes time to sell the house the deck wouldn't lose you money but rather increase the value & asking price of the home. Make sure you invest in high quality concrete, not just use cement with no aggregate (stone) in it. Give all metal 2 layers of primer and then a third layer of your chosen color paint. More effort for sure but you only have to tend to it once a year and the only thing to need replacing will be the horizontal deck wood (use pressure treated lumber). Easy-Peesy!
Thanks for leaving such a detailed comment and great suggestions.
When I used to do decks and fences in damp locations I would get roof cement and mineral spirits to thin and paint the bottoms of post never had any rot.
Whether the gravel retains water depends on the type of flow within the soil. If the soil is fine grained with smaller pores than the gravel and you have unsaturated flow, water will not enter the gravel because the water potential is much lower in the surrounding soil than within the gravel pores. If you have saturated flow and the soil is fully saturated around the gravel then it will move in but will then be pulled out again once you enter unsaturated conditions. Water always moves from high to low potential (the least resistance jargon largely comes into play under saturated conditions outside of soil.
Yes, I don't think gravel retaining water is going to be the big problem here, it's going to be when water from surrounding areas finds its way to any spots where it can accumulate.
I imagined that gravel was meant for a sturdy base that the concrete can penetrate into into when pouring in order to prevent the post from being exposed at the bottom, otherwise how are you supposed to set the post level and sturdy without some sort of "base plug"?
@ 6:47, absolutely. I worked in Fargo, ND, where they have clay soil and when we dug around the foundation footings to put in drain tile, or tubing, we covered it with pea rock, and the same thing on the inside around the footings, under the concrete floor, the purpose being as the path for water to travel to the sump basket, so yes that will be the path for water to go, to the gravel, which is at the bottom of the hole for the post, when in clay soil which holds water.
I live in a hurricane area and need to fix my fence should I use gravel in my case
I would try to find out what other people in your area are using and actually having good results with. My personal opinion is that gravel might make it easier to repair your fence when it is blown over by strong winds, but concrete could provide you with a little more structural strength to keep it from blowing over or out of the ground. Please keep in mind that I don't have much experience with this problem.
I used only pea tamped for a fence built in expansive soil. I inspected the fence and posts after 12 years and the fence is like I left it , posts in good condition.
Put black roofing tar on end of post that goes into ground. The gravel allows water to drain away from post bottom.
The gravel is a waste of time and materials!
How do you keep the gravel, separate from the concrete?
When you pour concrete over the gravel the thinner liquid will migrate to the gravel, making weak concrete of the gravel!
Also the binding cement strength that has wicked into the gravel has left the remaining concrete around the Post compromised.
How do you keep the two separate from each other?
I can just imagine trying to attach a bladder/seal to a sonotube, then installing the post and concrete without rupturing the seal!
Where high water table causes the rot problem then you might want to coat the underground portion of the post with tar to isolate the post from standing water or moisture to keep the post dryer. Moist soil can also create a rot problem that can be reduced by surrounding the post with gravel. Moist soil has higher surface tension than gravel, so as the water table declines or dries out a gravel filled post will be dryer than the surrounding soil---this is particularly true where the soil is clay.
If the post is encased in concrete which is less porous than the adjacent soil, the concrete will wick moisture to the post.
You can test these situations out in a glass aquarium. Put soil in the aquarium, dig the post hole up against the glass side of the aquarium and fill it with gravel or sand, then place a drip emitter on the surface of the soil in the aquarium and take time lapse photography of the plume of saturation. You will see that a gradient forms around the gravel and the gravel is slower to saturate than the soil around it; demonstrating that the soil's smaller finer particles wick the moister away from the courser sand and gravel, until the soil can wick no more moisture and then the gravel will saturate. Alternatively, you could place the emitter in the gravel around the post and repeat the experiment to observe the soil's ability to wick water out of the gravel and up into the surrounding soil---by a property know as surface tension of water.
I don't know if your method is going to work for everyone, but at the same time I've had a lot of viewers suggest that it works great.
Could you cover the base of each pole with a thick tar or epoxy before putting it in the concrete?
Should help lengthen its life from rot issues.
In my opinion it will create a water trap for any moisture that eventually absorbs into the wood post and works its way down, to eventually rot the wood.
+gregvancom
KK. You may be right So stainless steel posts for all fences from now on. Damn that will be expensive.
Kutulue Rust never sleeps.
+Patrick Kitts
Stainless steel does not rust if it has the right amount of chromium in it..
Kutulue That's an interesting idea but rust resistant stainless steel of high quality/chromium content is expensive and still requires occasional maintenance. That would not be possible if it were buried underground. (Unless you came up with a design that somehow made it accessible or easily removed and reinstalled!) If cost is not a factor it would be interesting to give it a try though. Somebody may have already for all I know. Titanium might be an even better choice because when it oxidizes a film of titanium oxide forms on its surface that actually makes it nearly invulnerable to further corrosion. They use it to make dive knives. How about carbon fiber? Many possibilities. Personally I have to consider the cost, which limits me to 4×4 or 6×6 wood posts. Then after having watched this video I'd be prone to choose my installation method based on the type of soil.
i have watched a million videos about posts and finally, next weekend mine are going in. I plan to use the old fashioned method of prepping the post with motor oil, then dry method concrete. Just dizzy with opinions lol
The best advice I could probably give you would be to build the fence in a way where these posts would be as easy to replace as possible.
@@gregvancom that is the reason why I am going to brush all of my post with a mix of motor oil and Diesel. They will never rot
@@MsLibrazen I understand and hope everything works out. I've never tried this method myself, therefore wouldn't be able to provide you with any guarantees to whether or not it would work. That's why I was suggesting to build the fence to accommodate possible future repairs.
@@MsLibrazen I understood what you were suggesting, just don't know how good it will work. Let's hope it lasts forever.
what about just back filling with like .5" in crusher, wouldn't that be less permeable than clay?
I've heard good things about this method, but don't know if it will work in windy areas.
How do I know what type of soil exists in my backyard?
It's difficult to explain. Soil with more clay sticks together and with less clay and more sand falls apart. Grab a handful of soil and squeeze it together and soil with more clay should form something firm.
I’m gonna start using the post setting foam instead of concrete from now on! Many benefits using foam for fence post, mailboxes and small structures!
ruclips.net/video/EesyOAW_sw8/видео.html here's a video that might help.
One problem that concrete around a post has it that even when it is sloped away from the post, the concrete does not commonly adhere to the post. Water running down the post's exterior will see some moisture wick in between the post and concrete. You can't stop that permanently. The gravel does stabilize the post base though, letting me install it and setting it vertically easier, by working it around. The gravel fragments, but resists moving against other fragments. Gravel drains more readily than sand, and sand more readily than clay. In the 19th century foundation trenches were dug deeper than needed for the brick or stone to be used. Sand was bedded into the foundation trench and then leveled. In Northern California redwood planks (2xs) would then be laid down as sills and leveled on the sand bed. The brick foundation was then laid on those wooden sills. This construction lasted very well, even in Sacramento, which notoriously flooded often until adequate flood defenses were finally built. This design is still found when renovating occasionally.
35 years experience in building decks/docks porches, I concreated one set of porch post in that was the first and last time after then I poured a pillar with a 16x16 box form on top drove rebar in the center then in the 4 corners tied in a couple of other pieces and set the post on top with the main piece of rebar sticking up 4 inches in the center and drilling the post to sit over it never had a problem sense, !
Not sure where you have seen standing water mate, Ive dug posts in several different types of terrain over the years and have yet to see standing water at depths where the bottom of a post will reside.
Try digging in areas with lots of water with in the top few feet of the top of soil and you will be surprised.
thank you for making this kind of informative video. I know little to nothing about home improvement, DIY, or construction. I need to construct a privacy fence and remodel some old rotted fencing on a family members' property and your video is one in a series i will view in an attempt to make my outing as a amateur construction worker a solid build.
You're welcome and thanks for watching. Don't forget to visit our website and check out the fence webpages for more videos.
Fence posts should be first treated to at least above the ground level with copper green (dilute copper napthenate in solvent) and then painted with roofing tar (liquid rather than paste), again above the ground level. The concrete footing should also be above the ground level (but lower than the treatment) and sloped away from the post.
this protects the base of the fence post against insect/termite attack as well as water-induced rot.
When this is not done, fence posts inevitably fail at the ground level.
Thank you common sense at last.
Well, with that reasoning, then why not use a circular plastic or other material form, then put that inside the hole, and put the post and fill with concrete? I'm sure there is some material that is impervious to water that can be used; of course, it will need to be flexible to a certain extent.
-----Also, I would think that all the fence pros out there know how to build a fence that will last 20 years or more. There seems to be no consistent answers about exactly the best way to set fence posts. In Philly, even some fence companies put chain link fence posts about 24" into the soil, while some others say to go a minimum 36" to get under the frost line.but at 36", at least in Philly, one runs the risk of drilling into water lines, etc. Call 811 before digging to try and prevent this.
---Going 36" seems to make sense to prevent frozen water in the soil from expanding up and pushing up the entire fence post-concrete combo. Word is that if it goes 36"+, tapered hole, and filled with concrete, then the concrete below the frost line will hold the post in the ground, below the frozen section.
--I'm no fence guy; I only know what I've been reading and people have been telling me. When I had an estimate done for my house, they said posts will go 22" down, and when asked about frost heaving, they just looked at me and just repeated "22 inches." What? So, I'm guessing that maybe they know the fence will not last as long as otherwise, if the posts go only 22" down, which makes more business for them
It is definitely frustrating and if you find something that works feel free to share with us.
If you're going to use concrete, you will have best results by pouring the concrete in a hole to a level above ground level & install a corrosion resistant "pocket" metal bracket. The post will be suspended above concrete & surrounding soil. You can adjust the length of your post for perfect fit at time of installation. You also can simply remove it or replace it any time.
Alternatively if your post has begun to rot out at ground level, you can save it (by cutting off at several inches above soil) removing it, dig a hole (removing the rotted out part) & pouring the concrete to the level to secure the bracket & post in place. The posts are usually sound, up from a few inches above ground level & worth the effort to reuse.
i've been working on a retaining wall in my backyard these last couple of weeks, 4" x 4" 1.8m total height. ultimately i decided on a gravel base with 2 engineering bricks, encased in cement for the posts. once set, i added more cement to the sides of the posts at ground level and tapered down, creating a small run-off, so no water would gather around the posts at ground level.
where i live, (sunny England) i have a clay/peat cocktail for a garden. with this in mind i chose to place DPC (Damp Proof Coarse) and a 'french drain' behind this retaining wall and backfill with aggregate. all pressure treated C16 timber posts used.
watched this video some weeks ago and it helped steer my decision making process.
many thanks. :D
Glad it helped and would love to see some pictures of your project. You can get our email address at the website.