Retired contractor with 50+ years experience, mostly remodeling. Now I'm a building inspector and code consultant. Batts are not the problem here. The high level of moisture in the air is the problem. It is going to go somewhere. Mitigate the moisture and then use whatever you want for insulation.
I have been building Encapsulations from Knoxville Tn to Kingsport Tn for 15 years. Refreshing to hear a completely accurate report. You are truly better off with nothing, rather than fiberglass batts. The rim joists is where 20% of all heating and air conditioning loss comes from because , like he said, nothing is there but a 2 x 10. In almost 1/3 of all homes, you can see the sunlight in and around the band joists (same as rim joists) because the 2" board is too hard to cut (and there's a lot of cuts) , we use 1" Owens Corning board. We pop a 1-1/4" roofing nail in the middle of the board to hold it in place while we foam around it. It's time consuming, but if you pre-cut the boards at the shop, it goes faster. There are lots of non-standard spots and many places where pipes or wires go through. It's best to get accurate measurements for those, and cut them at the shop and write on the PM with a marker. Last two hints. 1) Leave a space above the foam board to shoot the foam into. Foam doesn't have anything to sit on if you don't, and if you're going to drive a roofing nail (a box at Lowes is $3.88) you can't get a hammer into that area. Poke the nail into the foam board first and use something as an extension to hit with a hammer. We have a one inch round lead pipe that's 10 inches long. Very last hint. Major cities Home Depot and Lowes will rent a Fogger and both sell Concrobium Mold Control ($37 gallon, or $9.50 for 16 oz spray bottle) It kills every mold spore instantly and no mold can grow on that lumber again.....EVER !!!! I can't say enough about this product. Whole families were seeing the allergy doctor until we fogged their crawlspace . Angie Hicks of Angie's list made a video BLASTING allergy doctors for NOT telling their clients to atleast have their crawl space looked at. They must have made her take it down. Lastly, an air quality specialist costs four hundred and fifty dollars, you spend seventy percent of your life inside your home breathing God knows what.... these dudes are good and they have the instruments..good luck with your home,
fetty guapo Quite Welcome. I've seen everything from a 34 year old couple with three kids have to abandon their home, doctors orders. And I've seen Radon at a level 12 kill a 40 year old woman (lawyer) and I THINK that bat guano killed another gentleman. Tin roofs are great, but if the contractor doesn't put this fiber-like material under the ridge cap, and bats decide to make it a satellite home? Well, this fella ended up with them in the walls and everything. Histoplasmosis kills people and that's what he had. Almost every tin roof contractor puts the stuff, but when they don't, man it's like Russia roulette. Should be inspected. Darn shame to see somebody house harm them, or worse. It troubles me.
Troy Baker Good question : in Tenn. you can't take to board to the tops of the walls, as shown in this video. It must stop 4 inches below the tops of the walls. That's supposed to be so that termite inspectors can see mud tunnels. But I was a termite inspector too for nine years, and they prefer to come up through the dark, damp hollow block and eat from the inside out on the floor sill. TN code says to use R10 , or 2 inches of foam board in the band joists. We don't do that for just the reason you described. We use only one once. That gives the termite inspector room to jam a screwdriver into the floor sill to see if it's being attacked. By the way, Termites were totally defeated with the advent of Termidor SC in 2004. It's so dafe, homeowners can get it online. I do not understand anybody having Termites these days. Treat you own home every ten years.
UnderStructureRepair Thanks for the info in your reply. Do you know of a good reference for a homeowner applying Termidor SC? I'll continue looking at the product website but often professionals and DIYers have good tips on product use. Finally, thanks to NWOHI for the original video!
I had fiberglass in my rim joist cavities and two vents to the outside. During Chicago winters, the crawlspace temperatures would get down into the mid 30's and I was afraid that the copper water lines down there would freeze. I closed off the two vents and sealed the rim joists with Foamular R10 rigid foam boards and Great Stuff. Now, the crawlspace stays an average of 63 degrees all year round. Such a great, inexpensive DIY project with great improvement in comfort.
Thanks for the visuals. Seeing quite a few bad takes here in the comments. Simple summary: the fiberglass does not stop air movement. Moist air from inside the crawl space moves through the fiber glass bat and condenses on the cold rim joist. It's not likely to dry, and that's where the wet and black staining comes from. The solution here is to remove the fiberglass, cut and cobble rigid foam and seal the perimeter of the rigid foam blocks with spray foam. Care should be taken to choose the right rigid foam thickness for the climate zone to ensure the inside face of the foam remains above the due point. There are simple tables to find the proper thickness for your climate zone. This topic has been covered repeatedly on the green building advisor website and fine home building podcasts.
@Fred Wills yes, and this is an important point. Exposed foam is to be covered with some sort of flame retarder. The easiest solution here is to get the foam with foil face on one side that is fire rated. It's only marginally more expensive than the standard foam and it's still readily available at the big box stores (at least here in the north east). Plywood, or drywall are also acceptable in most regions and versions of the code, but who wants to do that?
Thanks! I was specifically referring to DOW Thermax which is foil faced and Class A Fire rated and can be left exposed. @@teamdada2194 If you have a good source that says otherwise please share I’d love to read it. www.dupont.com/content/dam/dupont/amer/us/en/performance-building-solutions/public/documents/en/thermax-sheathing-pis-43-D100094-enNA.pdf
@@billhamilton7524 hey Bud the band joist sits on the outside of your rim joist. It will be the outer joist that your floor joists are attached to. Hope this helps
I live in a cold climate and agree your summation is correct. Here we also need a poly (Visqueen) barrier anywhere low density foam or batting is used. We do not need or want to leave a strip of sill plate exposed for termite check because no termites here. Guess u don’t hv them either. I like your commment about being able to remove foamed-in sheet foam versus urethane sprayed foam. Good point. Cutting and can foaming is very labor intensive. You show a good example of how a good job looks. In a cold climate it would take 4 layers of 2 inch rigid foam to make me happy, with each layer can foamed. So I would bring in the urethane foam truck for almost all bays. I know u pointed out the batting moisture problem likely caused from vapor. I think u also mentioned the need to air seal the rim joists. In a multi story house there is a big stack effect with any air path from the basement. The man who built our house urethaned some sill bays, but in some bays he meticulously cut rigid foam blocks. Very neat precise cutting. Must hv had a hot wire. He did not can foam the cuts. During a remodel of ours we found his work. His hand custom cutting with no can foam was a BIG mistake. Terribly drafty. Found dead flys and yellow jacket small nests in locations one would swear a bug couldn’t get to. Harmless enough but the drafty issue I am sure stole much of the R value of his work. Thx for your vid. Good commentary from you.
I love your adding the comment about removing the glass batt rim insulation and installing the Extruded Polystyrene rigid insulation with the spray foam sealing. To put it mildly, “you have your shit together”. I’m a semi-retired professional roofing and waterproofing consultant with over 40 years of actual field experience.
Exactly. Also 1 1/2” strip to fill space below joists up to sill plate especially if it’s a block foundation. And zip tape the seams. Also at that point you can put the fiberglass back in.
Use Rockwool type bats and cut them to fit very very snug. Do around R25 to R30. You need the joists to breathe a little or trapped moisture will mold the joists. If the exterior is not Tyvek'd or sealed you will always have moist air intrusion.
When I insulate a band joist I start by caulking to stop the air infiltration as much as possible. I caulk the seam where the sill plate sits on the foundation, where the band joist sits on the sill plate, where the floor sits on the band joist, also there the floor joists hit the band joist (the nail holes leak). When you pull the pink insulation out you can see stains in it from all the air leaks. I used mineral wool the last time I did this because if a termite inspection is needed, they can move it out of the way without damage.
The contractor used fiberglass in my home's rim joists and I found mildew-ish growths in some, plus the Northeast corner in the master bedroom would form ice on the wall. I tore out all the fiberglass and paid to have proper foam in place. Cost for my 1800 square foot home was $750.
Spray foam or Styrofoam (blue board) to insulate the rim joist cavities (RJC), not a chance! Maybe you can get away with that Ohio or in the North but that’s a huge mistake in the mid-Atlantic and southern states where a risk of termites exist. Stay away from the blue board, use something of a better quality such as Hunter brand for the walls (it has dual sided fiber reinforced vapor barrier). Take the Hunter board up to within 2” of the top of the block/brick/cast wall and leave the 2” gap for a termite reveal. Next use RockWool insulation for the RJC to limit heat transfer, this allows for easy removal for termite inspection and it doesn’t absorb moisture as fiberglass will. You want to take it to to the next level then insulate the ground 24” horizontally in from the wall around the full exterior perimeter of the wall. Cover the entire ground with a class 1 vapor retarder (20mil) with 6” overlap at the seams and tapped with 4” vapor tape. Install an appropriate sized dehumidifier that will remove around 80-100 pints of moisture per day on a dedicated GFCI outlet. Upgrade your access door to seal tight with weatherstripping and insulated on the inside. Biggest take away for anyone reading this is to limit the use of spray foam in a crawlspace. I’ve seen spray foamed 6x6 beams with 80% rot because of trapped moisture. I’ve seen rim joists and joist tails completely decimated by termites and you could only tell by probing the wood with a wood probe (could actually stick a pencil through the lumber). Save the spray foam for inside the structure. Moisture in the RJC is not from “air transfer” as suggested, it’s a dew point issue. The exterior framing, if constructed properly, should have house warp with taped seams such as Tyvek for a vapor barrier over all exterior sheathing.
Hmm query what about snow areas seen most of cabins up big bear floors are insulated with insulation held in place with wire loops made and bent for that pourpose
Only person I’ve seen post a perfect response. I have a question… ever heard about staining rim joists to help prevent termites and rot ? Wondering your thoughts
Great thorough post, but on your taped seam Tyvek comment at the end, it's not a vapour barrier at all. Tyvek is not a vapour barrier. WRBs are meant to protect the envelope form bulk water ingress, but can act as an *ok "air barrier" when well taped. Not that easy unless you wrap xmas presents like it matters. Wind doesnt help. But it can help with energy conservation, in all climates by reducing wind wash of the envelope. WRBs are also meant to be applied shingle style with all Tyvek laps shedding water to the outside, from bottom to top. Need vented rain screen (siding) as well. Taping is secondary "air sealing", however it's hard to actually air seal a "whole house" this way because of the challenges of continuing this control layer from the upper walls through the ceiling (without a lot of forethought) Taped ply sheathing (with Siga, or other good sheathing tapes), connected over the top plates (blue skin band laid down before the trusses or rafters are set up), and then taped to a breathable air barrier (membrane) such as Siga Majpel, or other, on the underside of the trusses. Strapping then gyps (and shorter screws) to minimize the number of penetrations in this crucial air control layer. In place of the blueskin some people place a plywood bridge strip over the plate to connect the ceiling air barrier to. Tape this membrane to all penetrations through the roof and the stack effect is gone. ZIP now does this, but it's a Euro approach, originally. "Taped sheathing" Plywood and OSB ZIP are breathable, and combined with breathable membranes - in place of poly - makes for tight buildings and can avoid the problems of vapour drive in exterior walls, and moisture that does condense can dry in both directions later. Moisture moves on flowing air. Stop one, stop the other. Additional exterior insulation helps with bridging, and to push the dew point outside the envelope in very cold climates.
Cold-climate-liver (love it). Stack effect is real (and powerful). Vapour barrier is difficult to install as a defence at the rim joist (ten tubes of acoustic sealant later). I'm still assessing whether well-installed spray-foam will work better. As the house flexes from warm-humid to cold-dry I'm fairly certain cracks have been opening that I cannot see. Part of the problem is we over-"air condition" in hot weather and over-heat in the cold. We've only had a few decades to see what happens. Also...properly installed exterior insulation if you are doing a new-build (but investigate HVAC air exchange). In most districts these things are code where I live. If I were able to build a new house, I'm interested in insulated concrete forms...but you need a competent contractor. I'd also be happy with a tiny cabin and a wood stove, windows that open in the summer. Where I live it takes a century of shameful neglect before those things decay. I am fond of modern cooking/laundry appliances however..so get your electrical together..
Did you have a vapour barrier on the inside of the batt insulation? In the video, there was no vapour barrier on the inside portion of the batt - no wonder there was moisture migrating from inside to outside...
Again, same here. My house was built in 2001 in northern Ohio and no problems, the fiberglass batts are fit a little closer than just wadding it in there. They were cut about an inch oversized and they fit tight. My basement is dry, heated minimally and a dehumidifier runs in the summer. Have a good one.
We have rim joist batts in our 35 year old home and do not have any problems with moisture, mold, or other. The outside of the rim joist and side walls is covered with 1 inch Tuff-R foam, then Tyvek sheeting, then 1/2 inch t-111 siding. Works for us.
It's probably best to do inside and out if you use 1/2 inch foam on exterior But if you go any thicker on the outside then you're right inside is not necessary.
Makes sense. If the inside surface of the rim does not get too cold then it will not drop below the dew point, hence no condensation. How wet/dry is your basement/crawlspace?
The issue with bat insulation in rim joist is above that insulation is living space and. It will keep a cold floor 10 inches or so from the wall. As it's technically part of the outside not inside heated space now.
We have no exterior foam, but I have a New York home and also batts. No problems at all. I’m positive if I remove one now I’d see no issues behind it. I do run a dehumidifier 365 days/year keeping basement at 50-55
When we finished our basement, I used batts in the rim joist, then cut plastic to fit over the batts. Embedded the edge of the plastic in acoustical sealant then even added staples to hold it all in place. About 5 years later we noticed one of the basement rooms was abnormally cool. Started investigating and removed from suspended ceiling tiles in the basement and noticed that the acoustical sealant which was supposed to remain flexible had hardened and let loose in some areas leaving gaps between the plastic and floor joists. Pulled the plastic and batt insulation away to find a 1” thick layer of ice on the rim joist. 😕. Ended up taking the entire ceiling down near the rim joist and pulling plastic and insulating everywhere from the rim joists luckily only found a few more problem spots. Ended up cleaning up what mold had appeared, dried everything out then spray foamed the whole perimeter. Should have just spent the money on spray foam in the first place, way quicker install and complete air tight.
The approved way to airseal an open space is 2mil plastic sheeting (white flame resistant type if exposed) taped at all edges with 3” white tape. We use this in metal buildings all the time. Unfortunately using this for rim joists is difficult so I prefer 1” foam on the OUTSIDE of the rim joist but this is impossible on most retrofits.
@@MrChadder007 closed cell foam is a good insulator but it will crack over time losing all air sealing qualities. It is not acceptable as an air barrier that has to be inspected. Most rim joist insulation is not inspected, but might as well do it right I figure…
I have tried to explain this to people doing bad basement renovations. Run that foam board straight up in to each cavity to the plywood above, and spray foam around. Then you have even vapor transfer along the backside of the foam to the outside. Then your crawlspace or basement will stay fairly warm and dry compared to the outside air temp. In basements, you are essentially building a "bucket" with no leaks that your framing and finishes will sit inside, and you leave the outside area with the concrete and above grade wood to transfer moisture up and out. I recommend DMX 1 step for floor surface prep and then install tongue and groove wood sheathing over that. Then you will be giving yourself a little insurance when you have moisture events in your house.
Should mention whether this is an encapsulated crawlspace or a vented one, dirt floor or poured concrete. All factors to consider as moisture control is key in crawlspace. If encapsulated you will need some sort of method to control humidity (dehumidifier) and if it is a dirt floor then want to look at installing (minimum) 6mil VB and running it 6-10" up the wall (on the warm side of the rigid insulation then tuct tape all the seams - that way any moisture that builds behind the rigid foam will stay under the VB.
Mold is not a health hazard unless a specific black mold or if a person is particularly allergic to mold. Simply washing your hands after is all that is needed. Fiberglass can cause itching but at small encounters it's not an issue. I'd wear a mask if spending a lot of time pulling it down or installing it to avoid breathing too much of it.
@hugolafhugolaf The insulation you have is ancient and outmoded. The insulation in this video is modern and far superior. If you have the funds, an upgrade would work wonders. The difference will be night and day.
@@cquilty1Of course it is. It works though. My house, depsite dating back to 1970, is as energy efficient as any new home that is not built to super-stringent eco-criterias. And yes, I've had it tested. I was very surprised.
@@hugolafhugolaf A 1983 Geo Metro still works. But nowhere near as well as a brand new Honda Accord. The efficiency of insulation today compared with 1970 is vastly superior. Regardless of any eco pluses or otherwise.
@@hugolafhugolaf Ha! As already mentioned the difference would be night day. The square wheel is more useful/efficient than the insulation you have right now. Also, in the ensuing half a century plus since your insulation was installed, not only has insulation improved enormously, codes have changed and the R value requirements are far far higher But as long as you still enjoy driving that dented, oil burning, rusty old Geo Metro with springs coming up through the seats, that's the main thing:)
you need vapor barrier. the wood is the coldest in winter since the outside of the house is way below 55F which is the temperature of the ground inside. the moisture will condense on the cold wood surface. use plastic to block the moisture, then the fiberglass should work well.
Vapor barrier or facing on fiberglass ins. Will trap moisture against the rim board and will cause wood rot !! Either use fiberglass R19 unfazed or spray foam 3 in. Which is the best way .
Our house had the fiberglass batt insulation at rim joist in our basement when we moved it. The house is 40 years old. The wood at the rim rotted and we got mice and wasps making nests in that insulation, entering from the rotted outside overhang.
@@dwalto1977 absolutely wrong thing to do with fibreglass batts. Look into how fibreglass batts actually work. The plastic negates any benefit to the batts. Not trying to be a smart ass. Rigid foam board is perfect in conjunction with expansion foam.Just put the insulation batts vertically after the rigid (room side). Because there is no air infiltration through the rigid insulation you will have no problems. Of course a vapour barrier on the warm side- done.
Most building inspectors recommend UNFACE fiberglass insulation do to its fire rating. If you use foam board it must have an approved fire rating. If not it needs to be sealed up completely. Foam board will also trap moisture between itself and the rim joist. When you use any type of insulation your opening yourself up to trapping moisture between the insulation and rim joist due to outside moisture entering through the foundation wall. Always check with your local building inspector to see what he or she wants.
Foam board won't trap moisture if it's done properly. I think your whole fire rating theory is unjustified - your comparing two types of insulation at the rim joists, which I don't think is going to matter a whole lot if there's a fire ;)
Just speak to building inspectors about foam board being exposed, they will want to know its fire rating and how your going to give it a proper fire block.
@@thepinkdiamonds8370 , I understand what you're saying/getting at, but the building inspectors around here (and most I imagine, unless you're in a bigger city) don't care or even know about lol. I can't even fathom how many houses don't meet the fire ratings, you speak of, but I'm sure it's "quite a few" ;) I'm lucky to see a firewall in a garage lol. If it's of a concern, then use a fire rated foam board or similar. I know it certainly wouldn't be of concern to me for my house.
Northwest Ohio Home Inspections - ASPEC Residential Services, LLC , That’s what a state building code is all about. It doesn’t matter where you live in the state everybody should allows follow a unified code unless a inspector tells you otherwise.
@@thepinkdiamonds8370 Yes, that's what I said. I'm not saying you're wrong or right, but all inspectors/AHJ's that I know in my area do say otherwise and could care less about fire-rated insulation in a crawlspace.
The bats are not the source of the problem. It is the dirt floor that was not properly covered allowing moisture to wick up from the earth causing a transfer of moisture . Crawl spaces are cheaper than basements but you still should lay down plastic and cover with a cement slab then also allowing cross ventilation to reduce moisture transfer . Also plastic and some sort of mud slab or at cheapest a super moisture barrier prevent also radon . Helped a old friend build a cabin near a swamp once I told him this he did not listen . He sold the cabin to some people a year and a half later the living room floor collapsed in and he was responsible for the costly repairs . He called me and the first thing we did was double plastic and installed a concrete slab installed 6 vents and also a humidity meter . The cabin has not had a problem since .
In the northern climate the old timers would always say to not insulate basement walls from inside. The push of frozen earth on the concrete or worse block walls causes cracks even bulging. Insulation should be buried outside down at least 2.5ft . You can see after a snow that the outside perimeter ground around the bldg will be thawed this shows the heat loss but what is more expensive heat loss or hiring a foundation repair firm. Food for thought
The problem is high RH in an area with leakage, not batt insulation. Batt gets a bad rap because it’s in the right place at the wrong time (when air leaks and temp differentials are greatest. Too much humidity inside will result in condensation anywhere there is air leakage. Windows are no different. The rim leaks air just as any other area of a wood framed home. If you’re going to put any type of insulation in a joist pocket you need to make sure you first seal it so the batts can do their duty via thermal barrier. Batts are not sealers or vapor barriers, and when installed in a spot where it’s surrounding environment has high humidity with leakage, wahla you have condensed.
Exactly. I live in WNY and just pulled my non-vapor barrier rim joist fiberglass that was installed in the 70s to inspect things as I remodeled my unheated basement. The joists are perfect, no signs of dampness, no rot, no mold. Humidity drops like a rock in winter where I live. If your basement is occupied, then you need to seal the rims with a vapor barrier, just like the concrete walls should be. If not, then leaving them unsealed is fine. I run a dehumidifier set to auto mode all year... it keeps the basement humidity to under 45% or less.
Surely ventilate the crawl space to outside and insulate under the floor, with no ventilation from the house interior to crawl space. That way you will avoid warm moist air coming into contact with the cold rim joist.
Last time we remodeled, I had access to the crawl space and attic rim joists. Use airless to spray paint a good quality exterior paint (with mildewcide) the rim joist cubby hole area, including the end sections of the joists. Took about couple of hours and then went back and give it a second coat (dried pretty fast in the hot summer), sealing the seams and crevices. When the paint's all dried, came back to spray foam the seams and cracks. (spray foam cans) Then cover the entire rim joist area in attic with 6 mil clear plastic as moisture barrier, before sheetrock. The airless spray painting took about a half day; I used the other half day to spray paint the redwood fencing, so only had to clean the airless at the end of the day. For the rim joist paint, used OOPS paint where color doesn't matter; a $300 high quality exterior paint 5 gallons for around $30.
VAPOR BARRIER & TUCK TAPE One quick question...is the ground covered with a vapor barrier of some sort? Moisture and Argon gas will build up if the ground is not covered with some sort of vapor barrier. There is a 10 mil. heavy poly that is used under slabs, which can be used for this application. This will help to alleviate any ground moisture problems. Now if each rim joist gap is sealed with vapor barrier and tuck tape, or accoustic caulk / sealant, using fiberglass insulation is just fine. Any moisture within that crawl space will be stopped. But if you constantly have moisture coming up from the soil, the joists could eventually rot too. Vapor sealing the entire crawl space is what needs to happen.
Its not just the air transfer its the temperature difference causing condensation. Partially conditioned crawlspace with dehumidifier and blueboard, no fiberglass hydroscopic mold grower, use rock wool it breathes and is not hydroscopic and wont grow mold. Radiant barrier helps also. My crawlspace is at 65 degrees and 30 percent humidity. In house its 68 and 37 respectively.
I've read just about every comment listed for this video. I've determined that there is NO WAY of learning how to do this correctly by watching these videos. People in the comments have listed about 2 dozen different ways that they think it should be done. You would think mankind would've more fully evolved on this topic by now. It can't possibly be this controversial! Oh well, I'll do it my own way.
Thanks for watching. Everything, and I mean everything, is debatable, in this day and age with the internet :) You can find support and controversy for anything you choose to. My experience is from things I see day in and day out. Did you read the blog I wrote in the comments?
I agree. I sat here searching for the correct way to insulate the rim joists. Two hrs later , still sitting here searching. Its because there are too many know it alls! Just getting more frustrated. lol. Besides actual spray foam, there seems to be no correct way. My thought was to put 1" polystyrene, sealed around all edges, against the rim joist, and then putting in Roxul. It would fit snugly in there and is highly flame retardant. Mold resistant as well. ?? Sound good anyone???
@@terrythomas790 I sealed all edges with polyurethane sealant. In my opinion, this was 90% of the improvement as I had many areas with air leakage. Then cut mineral wool insulation to fit. My basement is noticeably warmer after this project. My whole reason for doing this in the first place was to find out where mice were getting in (found it).
@@nwohiohomeinspector btw, thanks for the great video. I still learned from it! All of my frustrated feelings are gone now that i'm done with this project.
Joisting on top of foundations walls like that is a bad idea in general. Even if you put rigid in there and make it air tight. That rim board is still going to be cold on the outside and hot on the inside and create condensation. Same thing will happen with spray foam. It just makes it all less visible.
Yes but sorry to say. "Right" isnt sealing the condensation into that wood. The moisture content in that 2x10 rim board should be pretty much 0 before you seal that rigid insulation in there. If it was me doing that I'd be using 6" of ISO minimum so that rim board doesnt get cold enough to sweat and create moisture and condensation again. Even with 2" rigid on that concrete wall it's still considered a "cold room". In Vancouver B.C it is anyway
@J Wil for the most part we bolt on a ledger to the concrete and hang joists off that. For the most part joists only bear on the foundation when they cantilever beyond foundation. Things are different everywhere though. It's a very wet and humid climate here
I too have been building for a while. Never seen mildew or mold cause by air transfer, if everything else is done within tolerances. The foam is great, but it’s highly flammable. Spray foam is even better. It makes a solid flex free glued together building. However, if you need or want to modify things, it’s a nightmare. Very easy to cut romex with any tool. So, R-19 in a 2x6 wall with type X 5/8 drywall, is my choice for applications.
Hello, You should have told the buyers that the “blue board “ should be covered up with type x drywall. Blue board is highly combustible. Roxul works extremely well too. Agreed fiberglass is a poor insulation.
@@unityroad smiling, I understand. How about that little part about leaving 5" exposed to show if termites are climbing the foundation.... Just saying. Thanks for the pet name, its been a long time since I've been called that. Im ok, you ok?
This is exactly what I did when I finished my own basement last year, replaced all the fiberglass batt with glued-in rigidboard and sprayfoam sealer. What a difference it made. Basement is warm and dry, heat bill is way less than what it was. Just wanted to reaffirm what this gent is saying.
Hi just a quick question. Are you saying it’s wise to remove all the fibreglass insulation in the basement and replace it with board insulation. My home basement came with Fiberglass and I’m thinking what’s the best to do. Should I keep the Fiberglass and frame it that way or should I remove it and replace with board before framing. Pls advise me. Thanks.
@lightning1086 if you have a Cement basement, the best option is to remove the fiberglass and add rigidboard to the concrete walls, tape the seams, spray foam around any gaps like joists, wiring, dryer vent, etc., then add your fiberglass back on, then vapor barrier.
In this instance nothing you have spoken to will eliminate the rim joist being a condensation point and thus in need of a way drying after condensation. I'm not sure I know how to deal with it. Joseph Lstiburek does, though.
Looks like a dirt floor in there so it would be important to direct the downspout water over 10 feet from the foundation, make all the difference in how dry your crawl space is.
I've been in my house for almost thirty years. It's stucco on the outside, has a basement that gets heat from the furnace. It had kraft faced roll insulation at the rim joist when i bought so, it's probably been there quite a bit longer than that. i've never had this problem. Maybe because that's a crawl space. I can't tell if the floor is dirt.
This is a classic vapor barrier scenario, not a fiberglass specific issue. Lower cost solution is to use faced fiberglass cut to size, with the facing stapled and tucked as with any fiberglass install. The facing on fiberglass is generally around 1 perm. EPS offers nothing, you'd have to use XPS specifically (blue board as mentioned, Foamular, etc)
I'm a professional installer and they don't sit right because they are too big and using a Kraft is better than an unfaced.. smaller squares fit beautifully and the paper on the bat helps tremendously..those "sandwiched" piece's belong as a blocker for a baffle on the roof..
Use spray foam at your own risk If the wood rots or insect damage, you don’t know until it is too advanced. If you sell the house, some banks will not approve a mortgage for that reason. Use Rock Wool cut to fit tightly instead
"Use spray foam at your own risk If the wood rots or insect damage, you don’t know until it is too advanced". Totally agree. "If you sell the house, some banks will not approve a mortgage for that reason" Curious, do you have something to back this up? I've heard of this for attic spaces, but not crawlspaces.
There should be a vapor barrier on the outside if not it was built wrong which would prevent that happening. The problem is there is way to much moisture in the crawl space and the fiberglass is soaking it up. The crawl space is the problem not the fiberglass.
I saw somewhere that if you place the fiberglass batt into a kitchen catcher plastic bag and slash an X in the outside side. This is a fast way to add a vaper barrier like the upstairs walls.
I've just seen 2"x10" or 2"x12" cutoffs plugged into the space. I'd like to see the rim joists a 40 year old house that has been sealed wit foam before I would do that to my house.
air flow is good, that is not your problem. your problem is that you do not have vapor barrier on the inside of your insulation like you do everywhere else in the house, the air moves right through as warm, moist, air and then condensates into actual moisture once it leaves the zone of the heated house inside of the insulation. you should cut a piece of poly for every joist spacing and acoustical seal it into place. I seriously cant believe you are an inspector. Styro is a good idea but I would still do batt insulation first so that the wood can breath instead of placing styro foam directly to the wood, that will lock moisture up against the wood with no way to escape.
I have an older house with a basement that has no sill plate. The wood sits directly on top of the blocks. Three sides are below grade and one is exposed to the elements. How do I insulate for that?
Don't know if I solved the problem or made it worse as I've since moved from the house, in Ohio but when i moved in there was batted insulation at the rim joists, I removed it and placed each batt into a heavy plastic bag ,sealed it and replaced them. No loose insulation to shed, no dampness in the insulation and cleanly removable for inspection. Never saw (over 15 yrs.) wetness, insects or mold. Perhaps just lucky, perhaps a solution?
The question is where the damp come from. Is it from the outside or from inside. In general I think it is a problem when the inspector likes or dislikes solutions. They are either accordingly to code, or not.
Looks identical to my crawlspace. The guy who built my house extended the floor joists directly out over the rim joist and build a deck on top of those. We had flooding horribly earlier this year so we had to remove the decks to.install proper perimeter drainage. We almost removed the front deck with the Excavator, could you imagine how bad that would have been if so...would have ripped my whole house down.. now I'm trying to square off those floor joists along the front and install a proper ledger, huge gaps and wet insulation was stuffed in between the joists just like in this video. It's been a complete nightmare. I'm about 1/4 of the way done. Perimeter drainage is in, backfilled etc but now it's making everything right. Or as rigjt as I can anyways Some people just shouldn't build houses! Total pain in the a@@!
Weak methods are indeed a dime a dozen. Some are driven by ignorance, some by lazyness, and some by lack of available materials. It's an almost endless source to explore - a series that could be called Uncle Lowball Adventures [in bad construction].
Another option if you want the extra insulation is install the rigid foam to the rim joist and spray foam/tuct tape seams then install your bat insulation on top of that.
Yep, fiberglass batt insulation performs poorly at rim joists, even worse in cantelvers, and bay window floors. Our master bedroom cantelvers out 24" for 14 feet. There was 8" R28 fiberglass batt insulation in there before , as soon as the outdoor temperature dipped near freezing, so was the floor. When it would drop way below freezing, that part of the floor was unbearable to step on first thing in the morning. I ripped all the batts out, and dense packed 9.5 inches of cellulose insulation in the cantelever. Now when the outdoor temperature drops way below zero, that part of the floor is only a few degrees cooler than the floor over the conditioned basement. I can't wait to do the same thing to the floors of my two bay windows.
Yes, you're exactly right! However, this video isn't about ventilation, which is another detrimental condition ( as I've said in a 100 other comments here ;) )
I did this in my basement about 13 years ago when I moved in my house in 2009. I just went and checked and I’ve got ZERO moisture, mold, or discoloration happening. It’s not a problem for everyone so I’m leaving mine alone.
Everything with construction is very dependant on the area. You could possibly be fine where you are at, and the fact you went in your crawl space to check puts you better than 50% of people already. Chicago is an area that is constantly moist. Lake Michigan, and marshlands make the area fight moisture constantly. So we have to prepare for these things, where an area like Arizona deals very very little with moisture problems. Roofing is done different in the two areas and many codes dealing with freeze/thaw conditions will make codes different from area to area. This is a recommendation, and I do believe a very good one. Polystyrene (blue/purple) board does not hold moisture, where fiberglass insulation does. All these small, but important details, matter when deciding what to do to your home.
I HAVE A LADY WHO IS EXTREMELY POOR HERE IN THE TOLRDO AREA THAT IM GOING TO ENCAPISILATE THE CRAWLSPACE FOR AND SHE CANT AFFORD TO DO IT WITH FOAM ,WITH THE FLOOR GOING TOBE SEALED WOULD IT BE OK TO SEAL THE CRACKS WITH CAN FOAM THEN USE BATT UNTIL SHE CAN GET THE MONEY . I CANT HELP HE ANYMORE ON COST BUT STILL WANT TO HELP OUT.....
Every house i work in now has spray foam there. Its a pain when trying to drill for silcoxs or anything for that matter because you cant see any wires that may be in a bay.
@@coreyfranco7060, it's in Appendix O "Foam Plastic Diagrams". It is an state amendment to the IRC. Each state can make their own amendments to the IRC so it may not be required in your state. I'm in NC for reference.
If the joists are embedded in the foundation, then I would not recommend this as it could trap moisture and rot the wood as well. Most people wouldn't have to worry about this but it's worth mentioning.
Yes, there is a moisture problem and yes I agree, isolating it from the outside and earth is the way all crawlspaces should be. However, and like some others have alluded to, the spray foam can be detrimental down the road, if there are future issues.
You have to seal those with vapour barrier and sealant OBVIOUSLY. It is a MASSIVE pain in the a$$ however, and it's really the only place where spray foam is a no-brainer.
Retired contractor with 50+ years experience, mostly remodeling. Now I'm a building inspector and code consultant. Batts are not the problem here. The high level of moisture in the air is the problem. It is going to go somewhere. Mitigate the moisture and then use whatever you want for insulation.
How do you recommend mitigating the moisture in an old basement, so the wood doesn't rot if I want to seal these areas?
I have been building Encapsulations from Knoxville Tn to Kingsport Tn for 15 years. Refreshing to hear a completely accurate report. You are truly better off with nothing, rather than fiberglass batts. The rim joists is where 20% of all heating and air conditioning loss comes from because , like he said, nothing is there but a 2 x 10. In almost 1/3 of all homes, you can see the sunlight in and around the band joists (same as rim joists) because the 2" board is too hard to cut (and there's a lot of cuts) , we use 1" Owens Corning board. We pop a 1-1/4" roofing nail in the middle of the board to hold it in place while we foam around it. It's time consuming, but if you pre-cut the boards at the shop, it goes faster. There are lots of non-standard spots and many places where pipes or wires go through. It's best to get accurate measurements for those, and cut them at the shop and write on the PM with a marker. Last two hints. 1) Leave a space above the foam board to shoot the foam into. Foam doesn't have anything to sit on if you don't, and if you're going to drive a roofing nail (a box at Lowes is $3.88) you can't get a hammer into that area. Poke the nail into the foam board first and use something as an extension to hit with a hammer. We have a one inch round lead pipe that's 10 inches long. Very last hint. Major cities Home Depot and Lowes will rent a Fogger and both sell Concrobium Mold Control ($37 gallon, or $9.50 for 16 oz spray bottle) It kills every mold spore instantly and no mold can grow on that lumber again.....EVER !!!! I can't say enough about this product. Whole families were seeing the allergy doctor until we fogged their crawlspace . Angie Hicks of Angie's list made a video BLASTING allergy doctors for NOT telling their clients to atleast have their crawl space looked at. They must have made her take it down. Lastly, an air quality specialist costs four hundred and fifty dollars, you spend seventy percent of your life inside your home breathing God knows what.... these dudes are good and they have the instruments..good luck with your home,
UnderStructureRepair damn man thanks for the knowledge
fetty guapo Quite Welcome. I've seen everything from a 34 year old couple with three kids have to abandon their home, doctors orders. And I've seen Radon at a level 12 kill a 40 year old woman (lawyer) and I THINK that bat guano killed another gentleman. Tin roofs are great, but if the contractor doesn't put this fiber-like material under the ridge cap, and bats decide to make it a satellite home? Well, this fella ended up with them in the walls and everything. Histoplasmosis kills people and that's what he had. Almost every tin roof contractor puts the stuff, but when they don't, man it's like Russia roulette. Should be inspected. Darn shame to see somebody house harm them, or worse. It troubles me.
What do you do about termite inspection? If you glue and seal blue board how will you ever be able to inspect for termites?
Troy Baker Good question : in Tenn. you can't take to board to the tops of the walls, as shown in this video. It must stop 4 inches below the tops of the walls. That's supposed to be so that termite inspectors can see mud tunnels. But I was a termite inspector too for nine years, and they prefer to come up through the dark, damp hollow block and eat from the inside out on the floor sill.
TN code says to use R10 , or 2 inches of foam board in the band joists. We don't do that for just the reason you described. We use only one once. That gives the termite inspector room to jam a screwdriver into the floor sill to see if it's being attacked.
By the way, Termites were totally defeated with the advent of Termidor SC in 2004. It's so dafe, homeowners can get it online. I do not understand anybody having Termites these days. Treat you own home every ten years.
UnderStructureRepair Thanks for the info in your reply. Do you know of a good reference for a homeowner applying Termidor SC? I'll continue looking at the product website but often professionals and DIYers have good tips on product use. Finally, thanks to NWOHI for the original video!
I had fiberglass in my rim joist cavities and two vents to the outside. During Chicago winters, the crawlspace temperatures would get down into the mid 30's and I was afraid that the copper water lines down there would freeze. I closed off the two vents and sealed the rim joists with Foamular R10 rigid foam boards and Great Stuff. Now, the crawlspace stays an average of 63 degrees all year round. Such a great, inexpensive DIY project with great improvement in comfort.
is the floor of C S dirt or slab ?
@@billhamilton7524 Concrete floor
Thanks for the visuals. Seeing quite a few bad takes here in the comments. Simple summary: the fiberglass does not stop air movement. Moist air from inside the crawl space moves through the fiber glass bat and condenses on the cold rim joist. It's not likely to dry, and that's where the wet and black staining comes from.
The solution here is to remove the fiberglass, cut and cobble rigid foam and seal the perimeter of the rigid foam blocks with spray foam. Care should be taken to choose the right rigid foam thickness for the climate zone to ensure the inside face of the foam remains above the due point. There are simple tables to find the proper thickness for your climate zone.
This topic has been covered repeatedly on the green building advisor website and fine home building podcasts.
@Fred Wills yes, and this is an important point. Exposed foam is to be covered with some sort of flame retarder. The easiest solution here is to get the foam with foil face on one side that is fire rated. It's only marginally more expensive than the standard foam and it's still readily available at the big box stores (at least here in the north east). Plywood, or drywall are also acceptable in most regions and versions of the code, but who wants to do that?
@@waltwinters9253foil faced is not fire rated bubs. Everything else I agree with.
Thanks! I was specifically referring to DOW Thermax which is foil faced and Class A Fire rated and can be left exposed. @@teamdada2194
If you have a good source that says otherwise please share I’d love to read it.
www.dupont.com/content/dam/dupont/amer/us/en/performance-building-solutions/public/documents/en/thermax-sheathing-pis-43-D100094-enNA.pdf
Cant say I have ever heard band joist ,can ,someone explain ??
Txs
@@billhamilton7524 hey Bud the band joist sits on the outside of your rim joist. It will be the outer joist that your floor joists are attached to. Hope this helps
I live in a cold climate and agree your summation is correct. Here we also need a poly (Visqueen) barrier anywhere low density foam or batting is used. We do not need or want to leave a strip of sill plate exposed for termite check because no termites here. Guess u don’t hv them either. I like your commment about being able to remove foamed-in sheet foam versus urethane sprayed foam. Good point. Cutting and can foaming is very labor intensive. You show a good example of how a good job looks. In a cold climate it would take 4 layers of 2 inch rigid foam to make me happy, with each layer can foamed. So I would bring in the urethane foam truck for almost all bays. I know u pointed out the batting moisture problem likely caused from vapor. I think u also mentioned the need to air seal the rim joists. In a multi story house there is a big stack effect with any air path from the basement. The man who built our house urethaned some sill bays, but in some bays he meticulously cut rigid foam blocks. Very neat precise cutting. Must hv had a hot wire. He did not can foam the cuts. During a remodel of ours we found his work. His hand custom cutting with no can foam was a BIG mistake. Terribly drafty. Found dead flys and yellow jacket small nests in locations one would swear a bug couldn’t get to. Harmless enough but the drafty issue I am sure stole much of the R value of his work. Thx for your vid. Good commentary from you.
If you want to avoid spray foam/foam board, rockwool batts do allow air transfer through the entirety of the batt unlike fiberglass.
I love your adding the comment about removing the glass batt rim insulation and installing the Extruded Polystyrene rigid insulation with the spray foam sealing. To put it mildly, “you have your shit together”. I’m a semi-retired professional roofing and waterproofing consultant with over 40 years of actual field experience.
Exactly. Also 1 1/2” strip to fill space below joists up to sill plate especially if it’s a block foundation. And zip tape the seams. Also at that point you can put the fiberglass back in.
Taping around vent box to reduce leaks into the space behind the drywall is a great tip!
Use Rockwool type bats and cut them to fit very very snug. Do around R25 to R30. You need the joists to breathe a little or trapped moisture will mold the joists. If the exterior is not Tyvek'd or sealed you will always have moist air intrusion.
When I insulate a band joist I start by caulking to stop the air infiltration as much as possible. I caulk the seam where the sill plate sits on the foundation, where the band joist sits on the sill plate, where the floor sits on the band joist, also there the floor joists hit the band joist (the nail holes leak). When you pull the pink insulation out you can see stains in it from all the air leaks. I used mineral wool the last time I did this because if a termite inspection is needed, they can move it out of the way without damage.
The contractor used fiberglass in my home's rim joists and I found mildew-ish growths in some, plus the Northeast corner in the master bedroom would form ice on the wall. I tore out all the fiberglass and paid to have proper foam in place. Cost for my 1800 square foot home was $750.
Spray foam or Styrofoam (blue board) to insulate the rim joist cavities (RJC), not a chance! Maybe you can get away with that Ohio or in the North but that’s a huge mistake in the mid-Atlantic and southern states where a risk of termites exist. Stay away from the blue board, use something of a better quality such as Hunter brand for the walls (it has dual sided fiber reinforced vapor barrier). Take the Hunter board up to within 2” of the top of the block/brick/cast wall and leave the 2” gap for a termite reveal. Next use RockWool insulation for the RJC to limit heat transfer, this allows for easy removal for termite inspection and it doesn’t absorb moisture as fiberglass will.
You want to take it to to the next level then insulate the ground 24” horizontally in from the wall around the full exterior perimeter of the wall. Cover the entire ground with a class 1 vapor retarder (20mil) with 6” overlap at the seams and tapped with 4” vapor tape. Install an appropriate sized dehumidifier that will remove around 80-100 pints of moisture per day on a dedicated GFCI outlet. Upgrade your access door to seal tight with weatherstripping and insulated on the inside.
Biggest take away for anyone reading this is to limit the use of spray foam in a crawlspace. I’ve seen spray foamed 6x6 beams with 80% rot because of trapped moisture. I’ve seen rim joists and joist tails completely decimated by termites and you could only tell by probing the wood with a wood probe (could actually stick a pencil through the lumber). Save the spray foam for inside the structure.
Moisture in the RJC is not from “air transfer” as suggested, it’s a dew point issue. The exterior framing, if constructed properly, should have house warp with taped seams such as Tyvek for a vapor barrier over all exterior sheathing.
Hmm query what about snow areas seen most of cabins up big bear floors are insulated with insulation held in place with wire loops made and bent for that pourpose
Bugs hate that RockWool insulation
Only person I’ve seen post a perfect response.
I have a question… ever heard about staining rim joists to help prevent termites and rot ? Wondering your thoughts
Great thorough post, but on your taped seam Tyvek comment at the end, it's not a vapour barrier at all. Tyvek is not a vapour barrier.
WRBs are meant to protect the envelope form bulk water ingress, but can act as an *ok "air barrier" when well taped. Not that easy unless you wrap xmas presents like it matters. Wind doesnt help.
But it can help with energy conservation, in all climates by reducing wind wash of the envelope.
WRBs are also meant to be applied shingle style with all Tyvek laps shedding water to the outside, from bottom to top. Need vented rain screen (siding) as well.
Taping is secondary "air sealing", however it's hard to actually air seal a "whole house" this way because of the challenges of continuing this control layer from the upper walls through the ceiling (without a lot of forethought)
Taped ply sheathing (with Siga, or other good sheathing tapes), connected over the top plates (blue skin band laid down before the trusses or rafters are set up), and then taped to a breathable air barrier (membrane) such as Siga Majpel, or other, on the underside of the trusses. Strapping then gyps (and shorter screws) to minimize the number of penetrations in this crucial air control layer. In place of the blueskin some people place a plywood bridge strip over the plate to connect the ceiling air barrier to.
Tape this membrane to all penetrations through the roof and the stack effect is gone.
ZIP now does this, but it's a Euro approach, originally.
"Taped sheathing"
Plywood and OSB ZIP are breathable, and combined with breathable membranes - in place of poly - makes for tight buildings and can avoid the problems of vapour drive in exterior walls, and moisture that does condense can dry in both directions later.
Moisture moves on flowing air. Stop one, stop the other.
Additional exterior insulation helps with bridging, and to push the dew point outside the envelope in very cold climates.
Cold-climate-liver (love it). Stack effect is real (and powerful). Vapour barrier is difficult to install as a defence at the rim joist (ten tubes of acoustic sealant later). I'm still assessing whether well-installed spray-foam will work better. As the house flexes from warm-humid to cold-dry I'm fairly certain cracks have been opening that I cannot see. Part of the problem is we over-"air condition" in hot weather and over-heat in the cold. We've only had a few decades to see what happens. Also...properly installed exterior insulation if you are doing a new-build (but investigate HVAC air exchange). In most districts these things are code where I live. If I were able to build a new house, I'm interested in insulated concrete forms...but you need a competent contractor. I'd also be happy with a tiny cabin and a wood stove, windows that open in the summer. Where I live it takes a century of shameful neglect before those things decay. I am fond of modern cooking/laundry appliances however..so get your electrical together..
My house was done 35 years ago with the fiber glass, I pulled them out and didn't see any problems. I live in Wisconsin, that might make a difference.
Same here, climate controlled basement rather than a damp crawl space.
@@woohunter1same, New York my basement is dehumidified, connected to main house hvac. and no issues with batts at all
Did you have a vapour barrier on the inside of the batt insulation? In the video, there was no vapour barrier on the inside portion of the batt - no wonder there was moisture migrating from inside to outside...
Same here
House built in 1986
No dampness with batt insulation
Basement is dry
This vid oversimplifies
Again, same here. My house was built in 2001 in northern Ohio and no problems, the fiberglass batts are fit a little closer than just wadding it in there. They were cut about an inch oversized and they fit tight. My basement is dry, heated minimally and a dehumidifier runs in the summer.
Have a good one.
We have rim joist batts in our 35 year old home and do not have any problems with moisture, mold, or other. The outside of the rim joist and side walls is covered with 1 inch Tuff-R foam, then Tyvek sheeting, then 1/2 inch t-111 siding. Works for us.
It's probably best to do inside and out if you use 1/2 inch foam on exterior
But if you go any thicker on the outside then you're right inside is not necessary.
Makes sense. If the inside surface of the rim does not get too cold then it will not drop below the dew point, hence no condensation.
How wet/dry is your basement/crawlspace?
The issue with bat insulation in rim joist is above that insulation is living space and. It will keep a cold floor 10 inches or so from the wall. As it's technically part of the outside not inside heated space now.
Do you live in a cold climate? If not, then obviously you wouldn't have issues. This only applies to cold climates.
We have no exterior foam, but I have a New York home and also batts. No problems at all. I’m positive if I remove one now I’d see no issues behind it. I do run a dehumidifier 365 days/year keeping basement at 50-55
When we finished our basement, I used batts in the rim joist, then cut plastic to fit over the batts. Embedded the edge of the plastic in acoustical sealant then even added staples to hold it all in place. About 5 years later we noticed one of the basement rooms was abnormally cool. Started investigating and removed from suspended ceiling tiles in the basement and noticed that the acoustical sealant which was supposed to remain flexible had hardened and let loose in some areas leaving gaps between the plastic and floor joists. Pulled the plastic and batt insulation away to find a 1” thick layer of ice on the rim joist. 😕. Ended up taking the entire ceiling down near the rim joist and pulling plastic and insulating everywhere from the rim joists luckily only found a few more problem spots. Ended up cleaning up what mold had appeared, dried everything out then spray foamed the whole perimeter. Should have just spent the money on spray foam in the first place, way quicker install and complete air tight.
The approved way to airseal an open space is 2mil plastic sheeting (white flame resistant type if exposed) taped at all edges with 3” white tape. We use this in metal buildings all the time.
Unfortunately using this for rim joists is difficult so I prefer 1” foam on the OUTSIDE of the rim joist but this is impossible on most retrofits.
Closed cell foam?
@@MrChadder007 closed cell foam is a good insulator but it will crack over time losing all air sealing qualities.
It is not acceptable as an air barrier that has to be inspected. Most rim joist insulation is not inspected, but might as well do it right I figure…
I have tried to explain this to people doing bad basement renovations. Run that foam board straight up in to each cavity to the plywood above, and spray foam around. Then you have even vapor transfer along the backside of the foam to the outside. Then your crawlspace or basement will stay fairly warm and dry compared to the outside air temp. In basements, you are essentially building a "bucket" with no leaks that your framing and finishes will sit inside, and you leave the outside area with the concrete and above grade wood to transfer moisture up and out. I recommend DMX 1 step for floor surface prep and then install tongue and groove wood sheathing over that. Then you will be giving yourself a little insurance when you have moisture events in your house.
Should mention whether this is an encapsulated crawlspace or a vented one, dirt floor or poured concrete. All factors to consider as moisture control is key in crawlspace. If encapsulated you will need some sort of method to control humidity (dehumidifier) and if it is a dirt floor then want to look at installing (minimum) 6mil VB and running it 6-10" up the wall (on the warm side of the rigid insulation then tuct tape all the seams - that way any moisture that builds behind the rigid foam will stay under the VB.
You're braver than me. I wouldn't touch fiberglass barehanded if I could help it. Especially if I suspect there's any kind of mold.
Mold is not a health hazard unless a specific black mold or if a person is particularly allergic to mold. Simply washing your hands after is all that is needed. Fiberglass can cause itching but at small encounters it's not an issue. I'd wear a mask if spending a lot of time pulling it down or installing it to avoid breathing too much of it.
I live in Quebec. It gets very cold. My house has had this type of insulation since 1970. No issues.
@hugolafhugolaf
The insulation you have is ancient and outmoded. The insulation in this video is modern and far superior.
If you have the funds, an upgrade would work wonders. The difference will be night and day.
@@cquilty1Of course it is. It works though. My house, depsite dating back to 1970, is as energy efficient as any new home that is not built to super-stringent eco-criterias. And yes, I've had it tested. I was very surprised.
@@hugolafhugolaf
A 1983 Geo Metro still works. But nowhere near as well as a brand new Honda Accord.
The efficiency of insulation today compared with 1970 is vastly superior. Regardless of any eco pluses or otherwise.
@@cquilty1 No doubt, but I have no need to invest some significant money to gain that last % of efficiency
@@hugolafhugolaf
Ha! As already mentioned the difference would be night day. The square wheel is more useful/efficient than the insulation you have right now. Also, in the ensuing half a century plus since your insulation was installed, not only has insulation improved enormously, codes have changed and the R value requirements are far far higher
But as long as you still enjoy driving that dented, oil burning, rusty old Geo Metro with springs coming up through the seats, that's the main thing:)
you need vapor barrier. the wood is the coldest in winter since the outside of the house is way below 55F which is the temperature of the ground inside. the moisture will condense on the cold wood surface. use plastic to block the moisture, then the fiberglass should work well.
This is correct, at least this is how we insulate houses in Sweden and other cold climate countries.
Vapor barrier or facing on fiberglass ins. Will trap moisture against the rim board and will cause wood rot !! Either use fiberglass R19 unfazed or spray foam 3 in. Which is the best way .
Our house had the fiberglass batt insulation at rim joist in our basement when we moved it. The house is 40 years old. The wood at the rim rotted and we got mice and wasps making nests in that insulation, entering from the rotted outside overhang.
My house has all those problems... Sad case
I did both with mine. Foam board insulation first with an adhesive, then Great Stuff around the perimeter of the foam board, then fiberglass.
Same. I also wrapped the fiberglass in plastic
@@dwalto1977 absolutely wrong thing to do with fibreglass batts. Look into how fibreglass batts actually work. The plastic negates any benefit to the batts. Not trying to be a smart ass. Rigid foam board is perfect in conjunction with expansion foam.Just put the insulation batts vertically after the rigid (room side). Because there is no air infiltration through the rigid insulation you will have no problems. Of course a vapour barrier on the warm side- done.
Foam board gets frost/condensation behind it too. Seen it myself on a partially exposed basement in Wisconsin. The wall is better to breath.
If I put foam on my walls my entire house would fill with mold in one season.
Most building inspectors recommend UNFACE fiberglass insulation do to its fire rating. If you use foam board it must have an approved fire rating. If not it needs to be sealed up completely.
Foam board will also trap moisture between itself and the rim joist. When you use any type of insulation your opening yourself up to trapping moisture between the insulation and rim joist due to outside moisture entering through the foundation wall. Always check with your local building inspector to see what he or she wants.
Foam board won't trap moisture if it's done properly. I think your whole fire rating theory is unjustified - your comparing two types of insulation at the rim joists, which I don't think is going to matter a whole lot if there's a fire ;)
Just speak to building inspectors about foam board being exposed, they will want to know its fire rating and how your going to give it a proper fire block.
@@thepinkdiamonds8370 , I understand what you're saying/getting at, but the building inspectors around here (and most I imagine, unless you're in a bigger city) don't care or even know about lol. I can't even fathom how many houses don't meet the fire ratings, you speak of, but I'm sure it's "quite a few" ;) I'm lucky to see a firewall in a garage lol.
If it's of a concern, then use a fire rated foam board or similar. I know it certainly wouldn't be of concern to me for my house.
Northwest Ohio Home Inspections - ASPEC Residential Services, LLC , That’s what a state building code is all about. It doesn’t matter where you live in the state everybody should allows follow a unified code unless a inspector tells you otherwise.
@@thepinkdiamonds8370 Yes, that's what I said. I'm not saying you're wrong or right, but all inspectors/AHJ's that I know in my area do say otherwise and could care less about fire-rated insulation in a crawlspace.
The bats are not the source of the problem. It is the dirt floor that was not properly covered allowing moisture to wick up from the earth causing a transfer of moisture . Crawl spaces are cheaper than basements but you still should lay down plastic and cover with a cement slab then also allowing cross ventilation to reduce moisture transfer . Also plastic and some sort of mud slab or at cheapest a super moisture barrier prevent also radon . Helped a old friend build a cabin near a swamp once I told him this he did not listen . He sold the cabin to some people a year and a half later the living room floor collapsed in and he was responsible for the costly repairs . He called me and the first thing we did was double plastic and installed a concrete slab installed 6 vents and also a humidity meter . The cabin has not had a problem since .
Roxul is perfect for those rim joists. Fast easy tight and effective.
In the northern climate the old timers would always say to not insulate basement walls from inside. The push of frozen earth on the concrete or worse block walls causes cracks even bulging. Insulation should be buried outside down at least 2.5ft . You can see after a snow that the outside perimeter ground around the bldg will be thawed this shows the heat loss but what is more expensive heat loss or hiring a foundation repair firm. Food for thought
The problem is high RH in an area with leakage, not batt insulation. Batt gets a bad rap because it’s in the right place at the wrong time (when air leaks and temp differentials are greatest. Too much humidity inside will result in condensation anywhere there is air leakage. Windows are no different. The rim leaks air just as any other area of a wood framed home. If you’re going to put any type of insulation in a joist pocket you need to make sure you first seal it so the batts can do their duty via thermal barrier. Batts are not sealers or vapor barriers, and when installed in a spot where it’s surrounding environment has high humidity with leakage, wahla you have condensed.
Exactly. I live in WNY and just pulled my non-vapor barrier rim joist fiberglass that was installed in the 70s to inspect things as I remodeled my unheated basement. The joists are perfect, no signs of dampness, no rot, no mold. Humidity drops like a rock in winter where I live. If your basement is occupied, then you need to seal the rims with a vapor barrier, just like the concrete walls should be. If not, then leaving them unsealed is fine. I run a dehumidifier set to auto mode all year... it keeps the basement humidity to under 45% or less.
As far as Air Transfer - I caulk around the ends of joist to where the rim is AND top of mudsill to rim - all around. The Rockwool.
Surely ventilate the crawl space to outside and insulate under the floor, with no ventilation from the house interior to crawl space. That way you will avoid warm moist air coming into contact with the cold rim joist.
My basement is not finished and never will be, did put rock wool around the rim joists. And it make's a big difference in my heating bill
Absolutely true. Speaking from personal experience
Would have liked to see what he recommended actually shown.
He mentions blue board with spray foam
@@rkalla He means a visual presentaion would be more informative than verbal description, and I also agree.
@@MT-cl3wx gotcha - thx
Imagine a blue rectangle with some sprayfoam lol
You literally read my mind with this video!!! Thank you. I’ll be adding foam board to the rims. 👊
Thank you for confirming what exactly what I was thinking of doing in the basement
Putting plastic on the ground helps as well
Fantastic this is exactly the way they did on my new house, bat insulation in my rim joists guess I need to redo it
If he caulked each rim joist area then add fiberglass insulation may not have condensation that causes it to stick or turn to meldew.
Last time we remodeled, I had access to the crawl space and attic rim joists.
Use airless to spray paint a good quality exterior paint (with mildewcide) the rim joist cubby hole area, including the end sections of the joists. Took about couple of hours and then went back and give it a second coat (dried pretty fast in the hot summer), sealing the seams and crevices. When the paint's all dried, came back to spray foam the seams and cracks. (spray foam cans) Then cover the entire rim joist area in attic with 6 mil clear plastic as moisture barrier, before sheetrock.
The airless spray painting took about a half day; I used the other half day to spray paint the redwood fencing, so only had to clean the airless at the end of the day.
For the rim joist paint, used OOPS paint where color doesn't matter; a $300 high quality exterior paint 5 gallons for around $30.
VAPOR BARRIER & TUCK TAPE
One quick question...is the ground covered with a vapor barrier of some sort? Moisture and Argon gas will build up if the ground is not covered with some sort of vapor barrier. There is a 10 mil. heavy poly that is used under slabs, which can be used for this application. This will help to alleviate any ground moisture problems.
Now if each rim joist gap is sealed with vapor barrier and tuck tape, or accoustic caulk / sealant, using fiberglass insulation is just fine. Any moisture within that crawl space will be stopped. But if you constantly have moisture coming up from the soil, the joists could eventually rot too.
Vapor sealing the entire crawl space is what needs to happen.
Its not just the air transfer its the temperature difference causing condensation. Partially conditioned crawlspace with dehumidifier and blueboard, no fiberglass hydroscopic mold grower, use rock wool it breathes and is not hydroscopic and wont grow mold. Radiant barrier helps also. My crawlspace is at 65 degrees and 30 percent humidity. In house its 68 and 37 respectively.
I was with you right up till the spray foam.
Right on 👍 Great example.
I've read just about every comment listed for this video. I've determined that there is NO WAY of learning how to do this correctly by watching these videos. People in the comments have listed about 2 dozen different ways that they think it should be done. You would think mankind would've more fully evolved on this topic by now. It can't possibly be this controversial! Oh well, I'll do it my own way.
Thanks for watching. Everything, and I mean everything, is debatable, in this day and age with the internet :) You can find support and controversy for anything you choose to. My experience is from things I see day in and day out. Did you read the blog I wrote in the comments?
I agree. I sat here searching for the correct way to insulate the rim joists. Two hrs later , still sitting here searching. Its because there are too many know it alls! Just getting more frustrated. lol. Besides actual spray foam, there seems to be no correct way.
My thought was to put 1" polystyrene, sealed around all edges, against the rim joist, and then putting in Roxul. It would fit snugly in there and is highly flame retardant. Mold resistant as well. ?? Sound good anyone???
@@terrythomas790 I sealed all edges with polyurethane sealant. In my opinion, this was 90% of the improvement as I had many areas with air leakage. Then cut mineral wool insulation to fit. My basement is noticeably warmer after this project. My whole reason for doing this in the first place was to find out where mice were getting in (found it).
@@nwohiohomeinspector btw, thanks for the great video. I still learned from it! All of my frustrated feelings are gone now that i'm done with this project.
@@jasonbohacek1130 was the a hole in the rim of your house?
Good tip, never knew that, will be removing mine!
Joisting on top of foundations walls like that is a bad idea in general. Even if you put rigid in there and make it air tight. That rim board is still going to be cold on the outside and hot on the inside and create condensation. Same thing will happen with spray foam. It just makes it all less visible.
Not if it's done right ;)
Yes but sorry to say. "Right" isnt sealing the condensation into that wood. The moisture content in that 2x10 rim board should be pretty much 0 before you seal that rigid insulation in there. If it was me doing that I'd be using 6" of ISO minimum so that rim board doesnt get cold enough to sweat and create moisture and condensation again. Even with 2" rigid on that concrete wall it's still considered a "cold room". In Vancouver B.C it is anyway
@J Wil for the most part we bolt on a ledger to the concrete and hang joists off that. For the most part joists only bear on the foundation when they cantilever beyond foundation. Things are different everywhere though. It's a very wet and humid climate here
If you use fiberglass,use the kind with paper backing. It’s a vapor barrier. Paint the wood before insulating
That dampness is shocking! I'll remember this lesson.
I too have been building for a while. Never seen mildew or mold cause by air transfer, if everything else is done within tolerances. The foam is great, but it’s highly flammable. Spray foam is even better. It makes a solid flex free glued together building. However, if you need or want to modify things, it’s a nightmare. Very easy to cut romex with any tool. So, R-19 in a 2x6 wall with type X 5/8 drywall, is my choice for applications.
Not romex
Hello, You should have told the buyers that the “blue board “ should be covered up with type x drywall. Blue board is highly combustible. Roxul works extremely well too. Agreed fiberglass is a poor insulation.
the wood framing is highly combustible too, oh and the sub floor plywood is combustible too...
@@trimbaker1893 Ok Dickhead every known Building inspection dept make you cover up foam, because of deadly fumes when burned.
@@unityroad smiling, I understand. How about that little part about leaving 5" exposed to show if termites are climbing the foundation.... Just saying. Thanks for the pet name, its been a long time since I've been called that. Im ok, you ok?
This is exactly what I did when I finished my own basement last year, replaced all the fiberglass batt with glued-in rigidboard and sprayfoam sealer. What a difference it made. Basement is warm and dry, heat bill is way less than what it was. Just wanted to reaffirm what this gent is saying.
Hi just a quick question. Are you saying it’s wise to remove all the fibreglass insulation in the basement and replace it with board insulation. My home basement came with Fiberglass and I’m thinking what’s the best to do. Should I keep the Fiberglass and frame it that way or should I remove it and replace with board before framing. Pls advise me. Thanks.
@lightning1086 if you have a Cement basement, the best option is to remove the fiberglass and add rigidboard to the concrete walls, tape the seams, spray foam around any gaps like joists, wiring, dryer vent, etc., then add your fiberglass back on, then vapor barrier.
Blue board is a termite play ground!
Up in Defiance! Toledo, my old neck of the woods.
I'm a building inspector. I write people up on this all the time: lack of vapour barrier. Best way is to scab foam into the space.
What does scab mean when referring to the foam board
@@WildGoose_F12 Cut into little rectangular sections and insert.
@@SirLionofBiffthanks!
In this instance nothing you have spoken to will eliminate the rim joist being a condensation point and thus in need of a way drying after condensation. I'm not sure I know how to deal with it. Joseph Lstiburek does, though.
Looks like a dirt floor in there so it would be important to direct the downspout water over 10 feet from the foundation, make all the difference in how dry your crawl space is.
I've been in my house for almost thirty years. It's stucco on the outside, has a basement that gets heat from the furnace. It had kraft faced roll insulation at the rim joist when i bought so, it's probably been there quite a bit longer than that. i've never had this problem. Maybe because that's a crawl space. I can't tell if the floor is dirt.
This is a classic vapor barrier scenario, not a fiberglass specific issue. Lower cost solution is to use faced fiberglass cut to size, with the facing stapled and tucked as with any fiberglass install. The facing on fiberglass is generally around 1 perm. EPS offers nothing, you'd have to use XPS specifically (blue board as mentioned, Foamular, etc)
I'm a professional installer and they don't sit right because they are too big and using a Kraft is better than an unfaced.. smaller squares fit beautifully and the paper on the bat helps tremendously..those "sandwiched" piece's belong as a blocker for a baffle on the roof..
If moisture developed, and eventually rot, with the fiberglass batt why wouln't it with what is being proposed?
Use spray foam at your own risk If the wood rots or insect damage, you don’t know until it is too advanced. If you sell the house, some banks will not approve a mortgage for that reason. Use Rock Wool cut to fit tightly instead
"Use spray foam at your own risk If the wood rots or insect damage, you don’t know until it is too advanced".
Totally agree.
"If you sell the house, some banks will not approve a mortgage for that reason"
Curious, do you have something to back this up? I've heard of this for attic spaces, but not crawlspaces.
There should be a vapor barrier on the outside if not it was built wrong which would prevent that happening. The problem is there is way to much moisture in the crawl space and the fiberglass is soaking it up. The crawl space is the problem not the fiberglass.
No, the moisture is condensing on the inside of the rim joist. The barrier needs to go inside that.
@@Cotronixco Yes, that is the true understanding. Use vapor barrier to block the relatively warmer moisture inside the space.
@@gahnyun2016 Paper faced fiberglass insulation? Paper toward the warm side?
I don't think they had vapor barriers in the 19th century when my home was built
I saw somewhere that if you place the fiberglass batt into a kitchen catcher plastic bag and slash an X in the outside side. This is a fast way to add a vaper barrier like the upstairs walls.
I've just seen 2"x10" or 2"x12" cutoffs plugged into the space. I'd like to see the rim joists a 40 year old house that has been sealed wit foam before I would do that to my house.
Thanks! You have pointed out some good points to ponder( for each) region n weather types!
What about Rockwool?
air flow is good, that is not your problem. your problem is that you do not have vapor barrier on the inside of your insulation like you do everywhere else in the house, the air moves right through as warm, moist, air and then condensates into actual moisture once it leaves the zone of the heated house inside of the insulation. you should cut a piece of poly for every joist spacing and acoustical seal it into place. I seriously cant believe you are an inspector. Styro is a good idea but I would still do batt insulation first so that the wood can breath instead of placing styro foam directly to the wood, that will lock moisture up against the wood with no way to escape.
All you have to do is sprayfoam each perimeter before the batt goes in. Done.
If the temperature difference is right you'll still get condensation.
@@randyscrafts8575 How?
I like how the codes completey seal up a home then HVAC recommends an air exchanger to bring fresh air experts right?
Cut/place properly whoever placed those shouldn’t be touching homes
I have an older house with a basement that has no sill plate. The wood sits directly on top of the blocks. Three sides are below grade and one is exposed to the elements.
How do I insulate for that?
Don't know if I solved the problem or made it worse as I've since moved from the house, in Ohio but when i moved in there was batted insulation at the rim joists, I removed it and placed each batt into a heavy plastic bag ,sealed it and replaced them. No loose insulation to shed, no dampness in the insulation and cleanly removable for inspection. Never saw (over 15 yrs.) wetness, insects or mold. Perhaps just lucky, perhaps a solution?
The question is where the damp come from. Is it from the outside or from inside.
In general I think it is a problem when the inspector likes or dislikes solutions. They are either accordingly to code, or not.
Looks identical to my crawlspace. The guy who built my house extended the floor joists directly out over the rim joist and build a deck on top of those. We had flooding horribly earlier this year so we had to remove the decks to.install proper perimeter drainage. We almost removed the front deck with the Excavator, could you imagine how bad that would have been if so...would have ripped my whole house down.. now I'm trying to square off those floor joists along the front and install a proper ledger, huge gaps and wet insulation was stuffed in between the joists just like in this video. It's been a complete nightmare. I'm about 1/4 of the way done. Perimeter drainage is in, backfilled etc but now it's making everything right. Or as rigjt as I can anyways
Some people just shouldn't build houses! Total pain in the a@@!
Weak methods are indeed a dime a dozen. Some are driven by ignorance, some by lazyness, and some by lack of available materials. It's an almost endless source to explore - a series that could be called Uncle Lowball Adventures [in bad construction].
Another option if you want the extra insulation is install the rigid foam to the rim joist and spray foam/tuct tape seams then install your bat insulation on top of that.
Will not work if you have an Orkin contract.
Yep, fiberglass batt insulation performs poorly at rim joists, even worse in cantelvers, and bay window floors.
Our master bedroom cantelvers out 24" for 14 feet.
There was 8" R28 fiberglass batt insulation in there before , as soon as the outdoor temperature dipped near freezing, so was the floor.
When it would drop way below freezing, that part of the floor was unbearable to step on first thing in the morning.
I ripped all the batts out, and dense packed 9.5 inches of cellulose insulation in the cantelever.
Now when the outdoor temperature drops way below zero, that part of the floor is only a few degrees cooler than the floor over the conditioned basement.
I can't wait to do the same thing to the floors of my two bay windows.
most moisture comes trough the earth floor . cover earth with 6 mill , need less vents
Yes, you're right, but that's not what this video is about ;) FWIW, 6 mil is the bare minimum and should be at least 10 mil, IMO.
Having the crawl conditioned and fully insulated is a best practice
I presume you haven't yet gotten to the part where a fire barrier must be on top (inside) of the foam blue board and how you do that.
Not even a few weeks ago I removed insulation from the rim joist and found black mold
That blue stuff is flammable!! Why not put some Roxul in there instead since Roxul repels moisture
Most unconditioned crawl spaces have vents cut in to allow that air transfer so what about all that moisture. So I agree with Wallace Grommet below
Yes, you're exactly right! However, this video isn't about ventilation, which is another detrimental condition ( as I've said in a 100 other comments here ;) )
I did this in my basement about 13 years ago when I moved in my house in 2009. I just went and checked and I’ve got ZERO moisture, mold, or discoloration happening. It’s not a problem for everyone so I’m leaving mine alone.
Where do you live? I’m in eastern Washington and it’s not super dry here but we still get moisture/humidity
Everything with construction is very dependant on the area. You could possibly be fine where you are at, and the fact you went in your crawl space to check puts you better than 50% of people already. Chicago is an area that is constantly moist. Lake Michigan, and marshlands make the area fight moisture constantly. So we have to prepare for these things, where an area like Arizona deals very very little with moisture problems. Roofing is done different in the two areas and many codes dealing with freeze/thaw conditions will make codes different from area to area.
This is a recommendation, and I do believe a very good one. Polystyrene (blue/purple) board does not hold moisture, where fiberglass insulation does. All these small, but important details, matter when deciding what to do to your home.
Just came across this & really like it. What would be better for this application, open or closed cell spray foam & for regular stud bays?
Where are the vents under the house to circulate air within the crawl space?
I HAVE A LADY WHO IS EXTREMELY POOR HERE IN THE TOLRDO AREA THAT IM GOING TO ENCAPISILATE THE CRAWLSPACE FOR AND SHE CANT AFFORD TO DO IT WITH FOAM ,WITH THE FLOOR GOING TOBE SEALED WOULD IT BE OK TO SEAL THE CRACKS WITH CAN FOAM THEN USE BATT UNTIL SHE CAN GET THE MONEY . I CANT HELP HE ANYMORE ON COST BUT STILL WANT TO HELP OUT.....
Im sticking with fiberglass. The foam can be deadly in any fire situation filling the home with extremely toxic smoke.
Rockwool is better, cut to fit tight.
Did you insulate between the joists as well, if so what did you use, or did you just use the foam board on the walls and rim joists? Thank you
Every house i work in now has spray foam there. Its a pain when trying to drill for silcoxs or anything for that matter because you cant see any wires that may be in a bay.
Yep, spray foam is the devil
I prefer air infiltration a little for my wood coal stove in basement keeps me from drilling holes through wall for added air
Here is short, more drastic video of what can happen to fiberglass batt insulation in crawlspaces: ruclips.net/video/F9vN5Rbas2A/видео.html
By code you are supposed to leave the rigid foam insulation board below the top of the concrete block 2" to allow for termite inspection.
Where is that in the code book?
@@coreyfranco7060, it's in Appendix O "Foam Plastic Diagrams". It is an state amendment to the IRC. Each state can make their own amendments to the IRC so it may not be required in your state. I'm in NC for reference.
@@jtltet ok, i didn't remember seeing this in irc...
@@jtltet which state?
@@coreyfranco7060 NC
Actually there's no vapor barrier there, that's the issue condensation there! The blanket insulation was not cut to fit snug either!
I always use Kraft insulation for rims joists. The paper is the vapor barrier
Would Killz and then flex insulation work?
If the joists are embedded in the foundation, then I would not recommend this as it could trap moisture and rot the wood as well. Most people wouldn't have to worry about this but it's worth mentioning.
Only thing missing was the vapor barrier. Facing the heated side of room? comment please
You have a moisture problem. Seal the vents, spray foam the rim joist, isolate the dirt from the house and dehumidify the space
@@miketonon7946 , no, because it makes a "solid seal" against that rim joist.
Yes, there is a moisture problem and yes I agree, isolating it from the outside and earth is the way all crawlspaces should be. However, and like some others have alluded to, the spray foam can be detrimental down the road, if there are future issues.
Todd Smith, sure, if one uses open cell spray foam. Closed cell works just fine in a crawl.
What about using Rockwool insulation there?
You have to seal those with vapour barrier and sealant OBVIOUSLY. It is a MASSIVE pain in the a$$ however, and it's really the only place where spray foam is a no-brainer.