Why Abandon "J" & "L" Anchor Bolts in Wood Framing Construction FOR GOOD?
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- Опубликовано: 3 авг 2024
- J & L anchor bolts have a long history in steel and wood construction. Some builders and framers still use them to this day. But with knowledge we've learned from failures of these bolts in other applications, and the advancement of other products and options, here are two reasons why I think we should phase out these kinds of anchor bolts all together.
0:00 - Hola
0:10 - What's the purpose of J/L bolts?
0:38 - J/L Bolt Flaw #1
1:52 - J/L Bolt Flaw #2
2:21 - Alternatives to J/L Bolts
3:52 - But here's the caveat...
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Legal Note:
This video is for informational purposes only and the information is not intended to serve as a contractual detail or legal advice for your specific project. While I might answer questions about unique situations, you should consult a professional licensed in the location of your project for a legal project solution unique to your project. I am not responsible for any attempt to implement an idea from this video for your project without legally consulting me or another professional licensed in the location of your project.
While the tone of this video may sound like I am against the use of J/L bolts period, there isn't really much documented evidence I've found that shows failures in wood residential or commercial construction as a result of J/L bolts. J/L bolts are still technically allowed in the residential code and your building official may not have a problem with them either. The intent is to pass information about the issues other industries have had with them that I think might be a good idea to implement in residential construction. If you've attached walls to concrete using J/L bolts, it's ok :)
I think J/L bolts have a place in very specific circumstances, however I do think there are much better options that are easier to utilize and do the job much better.
Ah, I read this after posting my comment.....
So the titan bolt and wedge anchors will do just as good of a job as the cast in bolt on for example use with at htt5 tie down?
@@johnjv24 the HTT5 is a hold down that’s typically used for shear wall tension hold downs instead of sill plate anchorage like here. I don’t think Simpson has tested wedge or screw anchors for that application. Wouldn’t hurt to ask them about substituting cast-in for post installed.
This is what they told me. I asked them a while back about using titan hd concrete screw with htt5.
“It is acceptable to use a Simpson Titen HD concrete screw as the anchor with our HTT5 tension tie connector. Always make sure to determine the anchor capacity for your installation conditions and use the smaller of the anchor or connector capacities when designing the connection.
Simpson has a web application called Holdown Selector that can help you select the best Simpson holdown and aid in the anchorage as well. I have included a link to this web application below.“
@@johnjv24 I didn’t even realize you responded…. My bad
in that case I would consider them for holddowns if the calculated uplift is small enough where it doesn’t require a deep embedment into the concrete. If it needs to be embedded deep, say 12”, I would go the cast-in option.
I'm also a licensed structural engineer specializing in residential and high end residential design. I don't agree with the conclusion to substitute post-installed options for cast-in-place anchor bolts. While most contractors are going to love your video and always ask for a post-installed substitute, it's not a one for one exchange. The capacity of post-installed options is substantially less than cast-in-place anchors. Not to mention that breakout is of equal concern and maybe even greater depending on construction practices and how the install went. Overall, substituting post-installed anchors for cast-in-place simply because they are easier to install for contractors is not enough to change industry standards. If your issue is with the breakout capacity being limited to the top of the J, then you can always substitute a straight bolt with a plate washer sandwiched between two nuts for substantially higher capacity. I think this video leads people astray.
Agree! That’s why there’s more information posted in the comments and description. Thanks for sharing! Cheers!
yeah, this video is bs
I agree, post install fastners are 100% about ease of use because contractors don't want to take the time or learn the skill of laying out J bolts. Laziness. The fastner manufacures are more than happy to go along because the J bolts cost less.
Cross grain bending of the wood is far below the bearing capacity of the L bolt (aka pull-out). Headed/nut washer should be used when up lift is significant.
So sandwich the concrete with washers basically?
J-bolts, with a linear rebar, running between them, laying in the "J" greatly increases the pullout resistance, and avoids wet setting issues.
Exactly! The poster of this video is just a shill for cheap and shoddy contractors.
Agreed! Terrible swap!
or better yet you could weld the rebar to the j bolts making them one.
@@jasonruff1270 Rebar is heat treated. When you weld it, it changes the tensile strength.
@@jasonruff1270 There are adjustable plastic brackets that can be screwed to the forms that can hold a J-bolt in place and you use tie -wire
to hold the rebar on the J-Bolt . J-Bolts with a rebar cage will outperform any after pour anchoring system . . . Period !
As a fellow engineer, I would have expected test data to prove the point. Mechanically, i don’t see how the 2 post pour options would provide more holding force. The cam lock is worse. The epoxy is the only solution that distributes more load to the lateral surface.
I agrée with you. At least the L bolt can hook on the concrete 1~2 inches around it. The post anchor bolt just use the force few mm around it. I seriously doubt the can provide the same force in the same condition.
J bolt everyday fam
And none of those bolts are meant to resist uplift anyway, at least not in the global sense of the whole house uplift that was discussed in the video.
Hold down anchors (bolts or straps) that resist uplift are generally cast in place anyway, unless it's a retrofit situation.
When we forget or mis-position an anchor bolt the engineers solution is always epoxy
It took me all of about 20 seconds to get a copy of 12 page specs on the bolts from Simpson.
In the bahamas we tie J bolts to the belt steel before forming up and pouring the concrete belt. So pulling them out would be impossible.
You generally don't want to use wedge anchors on a foundation stem wall (which is most of the time). The distance from the centre of the bolt to the edge of the concrete is too short to comply with the manufacturer's minimum requirements. You can even potentially blow out the concrete. The wedges push out and if the concrete is too thin, it will blow out. The close edge distance also substantially reduces the capacity of the bolt.
Yeah, I hate wedge anchors. They're far more of a hassle than any other.
Good video. We see L bolts in commercial all the time but they aren't those little things your are showing. Not only are they bigger in all directions, they are usually paired with the horizontal rebar, the "L" hooks under the horizontal.
In residential, IF you have enough wind to pull out a series of L bolts, you likely have much more important things to worry about. As an PE, you likely know the cause of failure is rarely one thing, the system failed not just one thing.
For the sleeve or wedge anchors, the only person that knows if they "grabbed" or not is the person who installed it unless an inspector is going to walk around with a torque wrench. Epoxy is good IF the installer, usually the unskilled crackhead cleans out the hole correctly. I never messed with screw in anchor bolts
Engineers need to stop trying to reinvent the wheel and just make a proven practice better. Make the horizontal part bigger and/or tile them to a horizontal and call it a day. 30 years as a commercial CM.
Agreed! This is a terrible swap!
I believe that this movie was created as a promo for the post-installed anchor industry. The code requires CIP anchors to be emended 7” min. which means that overall length of the anchor must be more or less 11”. Can you imagine how much the 5/8” diam. KB-TZ2 SS (they do not fabricate HDG stock) anchor of this size is going to cost? It is a major impact on the construction cost. Good luck! So, CIP anchors are here to stay. In addition to what I have said above consider the following:
1. To install post-installed anchors into the sill plate (review the ICC Report #4266, for example) you need to provide a continuous special inspection at the site which can only be performed by an authorized third party, special inspection agency. I can guarantee you that it will triple cost of installation compare to the CIP anchors.
2. Please also show correct anchors with standard 90 Deg. hooks, not what was shown at the beginning of the video. What you showed was a substandard anchor with a short tale. See ACI318 or CRSI manual for correct dimensions.
Good luck from California, SE.
Nice presentation and clear information, mate! However, I would avoid mechanical anchors, which induce increased stresses on a small section. I highly recommend the J & L bar as an engineer. But, as you said, it's more convenient to use other types of anchors for site difficulties. Chemical bond anchors are a good alternative after concrete casting, but, the downside is that it's expensive. A good engineer will sit down with his builder and discuss preferred construction methods and a budget, as some builders have more confidence to choose specific options.
None of the options you mention spread the tension load across concrete. A J bolt hooked on a horizontal rebar will far exceed everything for resisting uplift forces. But I definitely agree having to preposition the anchoring is a pain in the butt.
Very difficult to get the J bolt under horizontal rebar
The limiting factor are the nails from the sheathing to the sill plate and cracking of the sill plate.
How 'bout you show us the threaded and epoxy anchors being pulled with your test jig like you did with the L bolt? I'm having a hard time believing the concrete wouldn't break and blow out in the same way or that the bolts wouldn't just pull out. I just want to see it. Everything looks good on paper.
@Mastinox803 I believe a lot can be summed up in one word. 'MARKETING'
Practically, the post installed anchors would not be as strong as the J anchor bolts. Since you have to drill a larger holes with a lot of concrete dust, if test on sites, the J anchor bolts would have a better performance.
I've spent most of my career in the heavy industrial sector of structures. Almost exclusively plated rods. But for lighter work, post pore chemical anchors have never failed me. I love that they prevent water and chemical intrusion into the drilled hole. Great vid. Keep it up.
I was trying to find out how the wedge anchor worked, thanks for taking the time to explain their system. :)
I recently replaced a section of rotted sill and rim board on a 50year old house and discovered the block wall foundation had zero anchor bolts. The house was resting on the foundation and had not budged at all. Most barns in my area are sitting on stone foundations with mudsills in various states of decay and have no mechanical tie to the stones. I live in new england where we do not have tornadoes or hurricanes but it seems like this issue of anchors bolts just gets beaten to death.
And that is New England. If you look at Tornado tracks over the past decades of data collection you will find that nearly a Quarter of Lower 48 US territory fall within tornado activity. That is why you have code requirements and then you have accepted practices in certain areas.
fwiw. Growing up in a hurricane prone area that also can have some tornadic activity, most old homes, etc weren't anchored. I lived in a small 1910 house that was 10-15' above the mean high water mark and no floating away ever happened (heartpine house on brick piers). I dont condone it now, because I've also seen 'tied down' houses floated off their foundations and smaller homes partly sitting on trees.
This was by far the best video I found on anchor bolts. My next step was going to be finding the ICR code regarding them. The video took care of both. I might get banned from the channel, I plan to use L or J bolts for my project, lol. I don't have a hammer drill so an L or J bolt would be the easiest and most cost effective in my case.
I really enjoy your videos. Very helpful for my learning and you have a very effective way of presenting your material !!
You just earned a new subscriber son!!!🤙🏼
I’m a 35 year GC from South Florida where strong winds and Hurricanes are a big issue in my field. Inspectors are hard on us with matters such as the one on this video.
And you’re absolutely right about these concrete anchors!!
I appreciate your tips and I will definitely search through your other videos.
Thanx man!!!🤜🏼🤛🏽 and keep up the good work!!!
Hooray for you! Retired structural engineer. Never used a J bolt in my career but then again, I designed industrial structures. Anchor bolts were an issue from the start of my career until I retired 6 years ago. Mostly used threaded rod with nut on the end. You know the ACI has done a lot of research on this issue with pullout cone analysis, etc. J bolts are horrible. Kudos to you for highlighting this issue!!
Even the weakest anchor bolt will hold the plate to the floor long after the nails pull out of the stud.
In residential construction, check out uplift straps in hurricane zones or high seismic zones for example. True, nails play a large part in the diaphragm action of the structure but I see significant strapping here in FL where the uplift is transferred to the plate then the anchor bolts. Uplift is real and sure J bolts may suffice in some situations but IMO they are the least desirable type to use.
This was the most informative construction video I've seen. Loved this info! Thank you
I have used J bolts for 50 years. Never had any type of problems and I will continue to use them. Just because screw bolts are new doesn’t mean it’s better. Expansion bolts cause to much long term pressures on very fragile concrete. We pour all our foundations then insert the J bolts and will continue.
Good to hear, I'm digging and installing new footings for my garage previous owner never did and all the sills are rotted away and I didn't put in any J bolts so going to go for the 3/8 in hammer in anchor bolts. I use an Milwaukee SDS drill sooo much quieter than the old hammer drills.
I like this guy and he keeps explanations clear.
Hi Jay, good stuff.
Just want to add my two cents. Typically L & J bolts are used for shear load, not uplift.
Secondly, the wedge anchor might cause concrete spauling with close edge distance installations. Where the screw anchor at 1 3/4” isn’t a concern.
Thank you. Hold down anchors are cast in place anyway, unless it's a retrofit situation. There's no load reason not to use J bolts for lateral restraint.
The main reason not to use J bolts is- inevitably the layout gets messed up or framing changes and you end up with a bolt right under a stud or post and have to cut it off and use a post-installed anchor. After you do that a few times you think about just using post-installed to begin with. Then you remember how much they cost, and buy j bolts anyway and swear at the guys to do better on layout, lol.
In my experience . Ever notice the slot on a CMU unit . That is where an L is supposed to be hooked . Not too many masons take the time to do that . Most with just push one down and core fill with broken cull and slop mortar in the cell .. They all wiggle . On concrete .. Most will just push one down and wiggle it , most are out of plumb and require knocking straight which shocks the concrete , On the perimeters of monolithic slabs , Cracks the concrete and sometimes breaks off the concrete , The threaded anchors are fine . But they can shatter the perimeters as well when tightening thus rendering them useless.. In the field " anywhere besides and edge " . Epoxy has it's attributes as well . Drill the hole , blow it out and squeeze in the epoxy ..Yet in my experience .. If the hole has the least little dust .. It can be pulled up with ease when tightening So they really need to be cleaned out with with a damp cleaning tool . I find it hard to believe a sleeve or expansion anchor is better than a L bolt . Drill the hole and pound them in . They can be pulled up and out when tightening . So are you saying an L bolt can pull out easier than a sleeve. Wedge It ?? .. In a perfect world .. The J bolt is supposed to be hooked under rebar.. But few put the effort into making sure they are hooked and few put the rebar in the running location . It's always Blow and Go . In my experience I have worked on some " Beauties " When installing the mudsills . The carpenters would just use cut nails , case hardened , or a sinker . Basically worthless . Nailing into a CMU cell that has been filled with cull brick and topped off with a skimming of mortar !! LOL . . Many plates shook and made it hard to layout with plates doing The Shakes .. I remember watching on the local news , Houses floating off their foundations completely intact during a flood . LOL . Just recently . I couldn't work for a stupid builder . Had to leave . They were building basically a shed " Office " for what I called a Hooverville .. They were using anchor straps on a monolith and secured them to the plates with ... Aluminum roofing nails !!!! .. I jokingly suggested " Why not a thumbtack ?" they are basically the same . It wasn't until they said I was insane about setting a gatepost . They dug a 2' deep hole and set the 6x6 in and powdered in a bag of concrete and wet it .. Dry Packing !! . I said it aint worth a pile of dung . I even said " If drypacking is so good .. Then why don't concrete trucks just deliver the powder when pouring a footer ?" Imagine the fuel savings !! .. Next day I helped install the gate with a wary eye . I knew what was going to happen . Shimmed the gate in the hole and attached the hinges . Released the shims and the gate lurched in 2" .. rendering the gate inoperable !! LOL .. " Well You gonna have to fix that " .Years ago I had a saying " Why do it right , when you can do it twice and twice is twice as nice and a third time . Moi !!" .. I told them .. Here is the solution .. Did the hole bigger ! make an elephants foot hole , screws in some deckmate screws into the post . Like talons on an eagle and mix the concrete this time .. " Well we'll need a wheelbarrow !" .. Nope . Just a small tarp or piece of housewrap .Break the bag of concrete in the middle . pour in the water and pick up the corners and agitate !! . then sluice it in !! . I refused to participate in their stupidity anymore . I asked the builder " Is this the type of crap you build ?.. Count me out !!" See ya .. .. When I was hired .. He told the other guys " I don't know if I should hire him .. He's a super carpenter " .. I just wanted a little work while I am fighting Stage 4 cancer . I didn't want to run a crew again . I can't !! but I can be one hell of a hired gun when I am not sick . A few video ago .. You had a video about a balloon framing .. On one of this Builders projects .. They framed an 8' wall . and then framed atop it to the gable rafter . It shook back and forth 5 " with minimal effort . . I said "It should have been balloon framed " .. He said balloon framing is against Code !!! .. Huh !! .. The balloon framing he was talking about is where 2 story walls are framed and joist are sistered along the sides of the studs .. It's doable but anchoring must be perfect . I don't even do that'' Thats ancient . .. I told him .. It will continue to shake and poses a problem . The interior was vaulted .. I suggested .. at the very least .. stiffen the plate line with a LVL laid flat on the plate .. Turn it into a shelf !! . of put a perpendicular shear wall at midspan .. Use it for concessions in the future . Anything !! .. He said the collar ties will stiffen it and I was a jerk and said " No it wont" .. At these times .. You just bite your tongue and hope your eyes don't roll .. I ramble .. I have 40 years of experience and have seen most everything .. I have seen products that were revolutionary at the time , That ended up problematic . Most in the construction business are just about . Get it done with the least of money ,effort and hope nobody notices .. It's Bang Bang Bang .. Money Please . Most carpenters just follow and many don't consider the entirety . They were told and did . Check Please . . I have seen paid off Building Inspectors , Engineers that were hardcore and others were Slip and Slide . Architects that levitated and could do no wrong but had 100 mistakes per plan .Others that were sharp as a razor . Most custom homes have a myriad of problems looming in the years to come .. Remodeling business is booming
Wow ... 👍👍👍. I knew stuffs done using my own hands are the most trustworthy but never expect how bad it is ... if one leaves it to the "professionals"
I just came across your channel. I'm sorry to see that you have not continued but considering the last few years I am sure you have been an extremely busy engineer. I wish you the best. I wonder if you can explain considerations when building a single wall (2x6 16 o.c.) over 12' tall. God bless you.
Hang on here. I learned how to do foundations from an old high school buddy in the trade. It was not covered in engineering school.
Rebar is a big deal. The use of rebar I’d carefully documented. What I like to do and granted it’s tricky, is to slip the j bolt into the mud and then rotate it 90 degrees and slowly lift up.
What happens is the bend is now under the length of #4 rebar. You can feel it catch as you fish around.
Of course, one of the biggest problems is to put J bolts in the wrong place. Code dictates the placement schedule which sometimes interferes with the framing and sill plate. This is a pain. So the foundation drawing should show placement of these bolts.
When needed, I will augment or repair as needed using a Titan bolt by Simpson.
I watched this on 1.5 speed and enjoyed the way you explained the information. Thanks and god bless
Thanks for making this very clear.
Great video -- hope you do more content in the future.
Very insightful video!
Hey man just found your channel, really interesting and very simple to understand. I’m sure you come across cantilevers in buildings, can you make a video showing a cantilever home, where part of a bedroom is cantilevered, and how one would attach a deck to the cantilever.. I see people shockingly attach their deck ledger board to the outside of the cantilever with no load bearing beam/post.. certain failure will follow with a heavy snow load or multiple people on the section of the deck attached to Cantilever.. definitely needs to be addressed!
THANK YOU!!! Very helpful for my upcoming project!
I love your RUclips channel. You are a very smart person . Miss . Linda 💯
Excellent video. Thank you for the information.
Great video. Thank you!
Thanks for such an informative video. What would you advised to attach a shed to an existing hollow concrete block home?
This was super helpful. I wasn't aware of these.
Great info. Thanks for the vid, I Believe the Epoxy anchors are still required to have a Deputy inspector overseeing their install which will add to the cost. But both are great anchoring systems.
Excellent explanation. Thank you 🙏
Good info. I used on my deck but will not use for my cabin. Thank you sir.
I used all-threads with a washer and nut at the bottom in combination with two horizontal rebars running along the top of the foundation wall. For anchor plates I used custom made PL 5x3x1/2 with a punched hole. This size works well with both a 2x6 and a 2x4 wall plate and spreads the load across the hole width of the lumber for increased capacity. I also doubled up the wall plate in the bay with the anchor to increase the bending capacity of the wall plate. This also gave me more area for attaching the sheathing, which makes for a better load transfer. The problem with cast-in anchors is that one has to know exactly what the framing will look like to place them correctly. My anchors were installed pre-pour and concrete placement did rotate some of the anchors but they were easily straightened with a piece of pipe once the concrete had gained strength. The anchor threads need to be protected during the concrete pour so as not to gum them up. I used short pieces of PVC pipe with a duct tape cover. I have more confidence in these anchors than in any commercial system. It was a lot of work but this was for my own house and I wasn't going to cut any corners.
Great information! Thanks!
Thanks for explaining!
Thanks for the useful information 😊
I use the j-bolts as only to resist sliding on the foundation. I use QuickTie cables for my uplift counter measure. I am given the data to design with. You are so right about having only the 90 degree leg as the part with the load on it.
Very good presentation. I will be using epoxy-threaded anchors for my home project.
epoxy has it's own problems. nothing sticks to dust, and after you drill hole for rod (time consuming, btw) it is hard to get all the dust out. also expensive. J nd L bolts are cheap, easy to use, (contrary to what this video claims), and very effective. I would bet that they resist pull out better than the post installed solutions. especially if combined with rebar. Impossible to debate, though, because this creator offered no data to support his (wrong) assertions. I expected more from an engineer.
Great video. Thanks.
My experience is that drilling is easier and way more accurate without having to hang out material in the sill plate. Post drilled threaded bolts are commonly used in pole barn construction, and are more than adequate to hold the structure to the foundation. Having said that, I use j-bolts per code then add extra drill ins so that I have an anchor every 32”.
Post installed anchors are for people who can't figure out where the walls are going.
J and L bolts are less expensive and stronger according to the published data for similar sizes.
Good stuff! Thanks for the teach, teach!
What do the tests show if you throw a washer over the J before installing it? (This is assuming you can get the concrete around it without a big air gap.)
I liked your video, and I understand using it in plain concrete settings. However, recently I bought a house that is sitting on a cinder block wall foundation. The house is on a slope, and half of the house is sitting on concrete foundation ad the other half is sitting on cinder block walls.The cinder blocks are over 10 feet tall. I think it would be easy enough to put in j bolts inbetween the cinder block joints to fasten the sill plate, but since the top of open and exposed on the cinderblock, I am not sure what else I could do? I could try and fill in the block walls at specific points, but I think that would take a lot of concrete, and I am not sure if it would settle correctly. I am not sure if there is something else out there to use?
your house is not tied to the blockwall with anything right now?
in terms of just tying them together for fun, you can fill the tops of some blocks to make them solid and anchor into that. use whatever to stuff the blockwall void 8" or 16" below the top course so you don't have to fill the whole cavity. like pieces of tile or cement board. or fill the cavity 80% with gravel.
but if you want to tie to the blockwall for earthquake resistence, that involves giving the block wall tensile and shear strength, and when you attach to the plate on top, usually the entire cavity below is filled with concrete and a long threaded rod or rebar and an anchor.
if you're trying to resist wind uplift, just 1.5x or 2x the number of anchors. in the absence of an engineer's advice.
Text at 1:51 states: “J/L bolt failures have been linked to bolts slipping off the concrete along the vertical shaft.” I don’t know what your source is for this assertion, but it does not withstand theoretical scrutiny. First off, the bolt shown has clearly not failed; it is the concrete that has failed. Ideally, you actually _want_ to allow axial movement of the bolt w.r.t. the concrete at all points along the bolt, except, of course, deep at the fender washer or “J” or “L” area. Remember, concrete is strong in compression and weak in tension. Also keep in mind that the anchor bolt (as with all elastic materials) there will be elongation resulting from the axial force. If the bolt is bonded to the concrete, as the bolt is loaded, part of the load will be transferred to the concrete. Near the surface, you want all of the tension to be borne by the steel bolt, and none by the concrete, lest we see the failure type shown at 1:29. This why tape or tubing for the upper portion of the bolt is sometimes specified to prevent bonding to the concrete.
Good video Jay, also (for machinery installation) The Gas Machinery Research Council (GMRC) said that L and J termination should be just for auxiliary equipment
I agree somewhat, but for a house the L bolts should have plenty of hold down.
Also smooth shank vs threaded?
Here in Australia its all post installed anchors except for stuff that is big.
What I mean by big is say a radio tower you might use cast in bolts but weld them to the cage in some cases, but a tower is also side loaded which helps the L bolt.
As you said chem set anchors are very strong but they basically have a 75mpa resin in a 20 to 35mpa base material so you're still limited by the base material being concrete at say 20mpa.
This means cast in bolts are the strongest, not L bolts but rather threaded rod.
What I do is if I have a square steel plate I need to anchor if I can set it in before the pour just make a plate in the steel and one out to align the bolts and now one bolt is achored with a plate and 4 other bolts.
I spent the morning today hammer-drilling holes for expansion anchors in a new build. The contractor specified expansion anchor bolts (in addition to Ramsets) on all the interior and exterior wall base plates.
I'm a mechanical engineer, building my own home. I used L bolts as called out by the structural engineer, but upgraded to galvanized for a few extra bucks. In a few locations we needed additional bolts such as around doorways so we installed Titen bolts (screw anchors) in those locations. I loved using the Titan bolts and they were very easy to install. The concern I have is the design heavily relies on the integrity of the thread. It seems as if the thread would be the weak link over time as the thread corrodes and rusts. The thread is fairly thin so it feels as if it could decay relatively fast. I would suspect the galvanized layer is also somewhat compromised as the threads are twisted into the abrasive concrete. I wonder what kind of life span these bolts have been tested to.
That was very interesting.
It's one thing to talk about using other methods of securing mud sills, but quite another to get them passed inspections. My advice is to ALWAYS check with your local building dept.
Good video! Another reason to be a Garth fan!😂
What about tying the L bolts to horizontal rebar prior to pouring? I’m building a steel PEMB and was thinking having the guys tie the 1/2” rebar in the beam to the bolts.
For a PEMB I would recommend not using L bolts at all. Those buildings are very susceptible to uplift in high wind because they’re so light and the research into failures of those bolts have centered around PEMBs and L bolts. I would use a cast-in straight bolt with a heavy hex head embedded in the concrete.
I’m assuming you’re setting the frames on a slab with a grade beam so I’m going to run with that assumption from here. The horizontal bars likely do provide some help, but it’s vertical bars that would do the best to help prevent a failure due to uplift. But the horizontal bars do help in other ways without making this comment even longer.
I have done what’s called “tension anchor reinforcement”. “U” bars are put in the concrete in such a way where the vertical legs of the “U” align in close proximity to the base plate anchors, but it’s not tied to the anchor. The vertical legs just need to be in close proximity to the anchor. I suppose you could do this with L bolts, but I haven’t seen anything that says it should be tied to the anchors and I haven’t or know of an engineer that has done that. Again almost all engineers I’ve worked with & learned from designing steel buildings aren’t using L bolts because the organization responsible for writing the steel code recommends not using them. But there may be those engineers who don’t mind.
But lastly I would highly recommend you get a structural engineer to provide foundation drawings. If your building is a simple rectangle and small, a competent SE could turn that around for you very quick for not a lot of money and give you the peace of mind of a sound foundation system.
Hope that helps!
I didn’t know J-Bolts were used to withstand uplift loads. That is why engineers specify hold downs with specific uplift capacity based on the conditions or structural calculations results.
Good info
You showed one pull-out test, do you have the data that shows the best anchor that resists uplift?
Love it.
Thanks!
Just wanted to say thank you! I love creators like yourself who can help most of us see past the "what's good enough; it's been done that way for ages" to understand why other options may be better.
you switched from calling out the L anchors for not having enough uplift resistence, to alternatives that are easier to install (good) but also don't have definitively better uplift resistence. what anchoring methods resist net uplift best?
Wiggly bolts
I read North Carolina 2018 Foundation Codes and could not locate texts mentioning that anchor bolts can be replaced with other types. Did I interpret the code texts inefficiently ? This project was small 12x15 feet room addition; hence went with J/L anchor bolt.
NC likely doesn’t have a specified type of anchor either in their code. It probably just mentions the size of the anchor, the spacing, & how far it should be embedded. As long as you met that, code wise you’re ok.
I forgot to mention however that companies who produce fasteners, such as Simpson, have their own literature on anchors that can be used as a equivalent substitute for a sill plate anchor. I've attached a link to the screw anchor I had in the video here.
ssttoolbox.widen.net/view/pdf/fizor1uvtv/T-A-SILPLANCH21.pdf?t.download=true&u=cjmyin
Would like to see your hypothesis in a lab setting using all the requirements for a complete evaluation of all anchors vs the one you're pushing.
Subscribed! I’m sure gonna look through your stuff. At the moment I’m trying to find out which Simpson post-framing anchor bolt is needed to be equivalent to or better for hold down than a 1/2” J bolt with a 7” embedment.
lol do they even sell those that long??!
@@zhugeliang777 Well 10" bolts are available that I know of. I'm almost sure you can get longer too.
Turns out, a Titan bolt 1/2" thick with a 4 1/2" embedment is equivalent to the 1/2" J bolt with a 7" embedment.
I'm interested in that research also. Where did you find it? Would you share?
Thanks.
What size thread anchor bolt do you use ? Length and diameter?
Very nicely done. Thank you. raphael nyc
Nice video.
But, I'm not sure if I agree completely. Firstly, it is not difficult to install J/L bolts. Those in the trade have been doing it for litteraly decades w/o issues.
Secondly, where is the proof (aka testing video) showing J/L bolts failing due to uplift forces? And, thirdly, I deal with structural engineers all the time and most (if not all) of the specifications for AB have been the typical J/L bolts.
Of course, using the screw-in bolts, and the expansion bolts are also good choices if the concrete is already poured. Otherwise, I don't see why a structural engineer would phase these out when they are perfectly fine and gets the job done 100% of the time (provided its new poured concrete). Thanks.
At 1:22 into the video he makes reference to uplift failure.
Great video, and I agree with your comment. I personally do not recommend expansion bolts or adhesive anchors at slab/foundation edges. If bolt placement is missed, we do use adhesive anchors, but installed at a slight angle.
Also, it bolt is going to be used to resust uplift. I do not use J-bolts, I design and use treaded anchors with a nut and wssher.
Interesting video, the comments contributors are as interesting. I've used L bolts for over 50 years. I like them but one needs to be careful where you place them.
I agree the j bolts are harder to install but they are probably cheaper too. And no way are the drilled in anchors as strong. I like the drill in anchors because I am not a pro, just a homeowner.
Do you know how much work and study it takes to earn a PE license, and how many people fail the exam? If he says a post-cast anchor is stronger, you should take his word for it, because the architect designing your house calls him up when he has questions about structure.
This isn't a phony engineer like Elon Musk or Stockton Rush.
can't find videos for screw anchors and like what drill to use and depth of drilling etc.
Look for videos from Hilti, Simpson Strong-tie, or Titen. All 3 manufacture screw anchors and Hilti also manufactures equipment. That’s about the most you’ll find on them currently.
An SDS hammer drill would work for the application similar to what’s described here. Hammer drills typically are used for holes smaller than 1/2 inch. Depth of drilling is on a project specific basis, but architects, structural engineers, or the code may give you that info too.
Thanks so much for confirming my suspicion that j-bolts are very difficult to install correctly.
In your opinion what is the strongest concrete anchor bolt for uplift? I’m building an OVER THE TOP (structurally) icf house in south Florida and what the most bomber way to attach my joists for truss hangers? Thanks in advance
A straight, cast-in anchor bolt with a square or hex head at the end is my 1st choice.
Not sure if there's a "best" way to attach trusses to ICF, but I generally see trusses bear on double top plate & fastened with 1 or 2 Simpson hurricane ties each side. But I have used a truss anchor that's embedded in the concrete. Look up "Simpson META with TSS". I just don't use them often because when I have the contractor has always messed them up.
Jay u r confusing me - u spend a whole video raising issues with cast in j and l bolts because the horizontal leg is do short then you say your best approach is use a straight cast in anchor bolt - ie NO horizontal component??!!
www.eng-tips.com/viewthread.cfm?qid=416314
In this thread you’ll should see a photo of 5 different cast-in straight anchor bolts. From left to right depending on the situation I’ll specify 1, 4, or 5. That’s what I mean when I say “straight”.
@@JthaEngineer I agree with John, it seems like the point of your video is that you think post-installed expansion bolts are stronger than cast-in bolts. Then in the comments you say the opposite.
I do like the post-pour fasteners, however, wonder how long the concrete has to cure before installing either the wedge or screw fasteners. I'm assuming that the drill/epoxy system could be done the day after the forms have been stripped.
J bolts which are wired to and hook on a horizontal rebar before the pour do not pull out. Rebar threading is also a good option which is used where I live in California.
A screw anchor will never end up in the middle of a stud . You also don't have to lift the walls up and over the anchors. Stand the wall up square it and pin it to the foundation. Post install anchors are great😎
If you actually design a house first instead of freestyling it, nothing will end up anywhere except where it's supposed to.
@@canonicaltom Great in theory. Nobody designs a house beyond the 'technical concept' level, though, so every builder wings it. Full design means LOD 500, which I have not heard of in contractor-grade residential housing. Re 'If you actually design a house first instead of freestyling it, nothing will end up anywhere except where it's supposed to.' - sounds like you are not a builder LOL, because in practice nothing matches the original design unless you're doing digital fabrication.
@@marcinjakubowski6010 In my area, you can't get a building permit without having a complete architectural drawing specifying where every stud, joist, fastener, bolt, shingle, feedthrough, or electrical outlet will be. And the inspectors will void your permit if you don't follow the drawing.
@@canonicaltom Well I don’t know about Voiding your permit. But you will spend lots of time talking to your Architect and Engineer. Anything they put their signature on, like a fix will cost you plenty.
@canonicaltom Agreed. Never has a "J or L" bolt ever failed on my job sites (almost 30 years in the industry.)
If an "L" bolt is in the way of a stud, either cut around it or cut it off and replace it with a Redhead.
Now, how many Redheads have ever failed me? TOO MANY TO COUNT.
Structural novoice here. Question, wouldn't it be great to make U bolts? Even better if get them go under horizontal rebars during concrete pouring?
How long after pouring before you can drill and install a Tapcon?
That's crazy!
I’d recommend using epoxy with tapcons. I drilled the right size hole and used them but they free spin in the hole after tightening. It’s a basement wall non load bearing so I’m not worried about it. I put the studs in after the sill because I didn’t have room to work with so it’s really tight to the floor and doesn’t have any lateral movement. If I did it again though. I looked for the epoxy at Lowe’s made for anchors, none in stock. I don’t know if all epoxy is the same or not.
On the Japanese video, they also use the L bolt, and also as a way to hold parts of the sill down temporarily while straightening the rest of that sill to the chalk line. So, it's not useless to precision nerds. Maybe I could add a few screw or wedge anchors on the 4 corners of the sills after if it pleases you.
Always hooked "J " bolts under the rebar.
How would any thing just pushed into wet concrete have any holding power???
Tim
My community garden would like to build a 12 x 16 gazebo. The kits they sell require you to bolt it to concrete, but our landlord doesn’t want concrete. So we’ll need deep footings… What I’m wonder is, will bolting our gazebo posts to wooden footings be strong enough?
Hi FreedomFox1, try ground anchors these are basically large screws that can be moved or removed as needed. Search for "American Earth Anchors" they are not cheap but they are good for just about any soil and have loads tables. The larger versions allow for direct support to a beam. I used them for a solar mount and a small structure. The version I used had a top sized for 2 inch iron pipe. I used short sections of pipe with threading to attach to a small iron floor flange plate. The plate forms sort of a small adjustable platform to sit a few wood beams on. Once I got the beams level (the screw thread allows fine vertical movements) I used 4 lag screws to attach the beams then built my small structure on top. The screw anchors can have several thousand pounds of uplift resistance. hope this helps.
-MG
my cousins husband worked for Napa and went to a trade show where they demonstrated using the epoxy --seems the epoxy Vapor extends out into the concrete expanding the area of adhesion.. other types of hold downs pulled out with little concrete damage the epoxy consistently pulled out a 4 to 6 in section of concrete!!!!
When I built my garage I did the j bolts on the block. However, I think both are fine, they both prevent uplift but at some point if the force it to much then both ultimately fail. It’s still better than nothing on the sill.
In California all post-set anchor bolts require deputy inspector,
so Ive only used when there is screw up and bolt is missing or misplaced.
Also J/L Bolts are not used as for holddowns in shear wall . just to keep bottom plate from kicking out and against minimal uplift /shear forces.
Much longer curved / S shaped and inward angled bolts used for holddowns , SSTB16's ect...never j bolts.
Also always use Simpson strongtie anchor mate holders make setting all bolts pre-pour easier.
Those 2 post vehicle lifts come with 5/8 inch wedge anchors and need 4 inches minimum concrete thickness, recommended 6 inch thick. I used 12 inch x 3/4 j bolts thinking that had to be better than 5/8 wedge anchors. I sawcut the concrete out, dug down 3 feet, tied rebar, tied the j bolts under the rebar, vibrated the concrete. I was a little nervous about 5/8 wedge anchors holding up 10,000 pound vehicle lift.
J anchors can also be set before concrete by suspending them in piece of lumber across the concrete form. Little extra work, but more confidence they`ll be set right.
I discovered those Titen HD bolts/screws(?) recently. They are so much easier to work with than J bolts. Wish I knew of them years ago.
is it true that you need at least 7" in the concrete?
I have used many AJs and other anchor bolts and I would always use cast in place first given the option.
J bolts are the way to go with new construction as they prevent drilling concrete and dust exposure.
There’s the structural design and there’s the builder. In the garage at my home growing up, we widened the garage and found one of the J bolts was just the top inch, there to fool the building inspector. It must have landed under a stud, so they cut it off, and drilled a hole next to the stud, put a washer and nut on, and dropped it into the hole they drilled.
what about j/l bolts tied to rebar in the foundation?