Seismic Retrofitting The Post to Beam Connections
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- Опубліковано 18 лют 2019
- Retrofitting the post-to-beam connections is a complete waste of money. The building code says so, common sense says so, and the government says so. Why do so many people do it, then?
Seismic retrofit engineers and contractors often speculate about what will happen to a house in an earthquake and do not look at the evidence. Experience tells us post-to-beam connections do not increase or decrease a home's ability to resist earthquakes.
Go to our website to learn more and ask us to come look at your house.
bayarearetrofit.com/
Man, thank you. Just took the first of three bids for an EBB retrofit and the guy included an optional line item for retrofitting the posts. Thanks for the explanation.
Thanks for this video. I only have 8 post and beam connections in my crawl space but this saves me ~$200 that I can use for retrofit material that I actually need!
Extremely helpful. We are in north Oakland and assessing the viability (cost) of doing an extension and/or garage conversion ADU and this has really helped to educate me.
Thanks for letting me know. Helping people like you is the reason I put the website together
I was qouted $7500 for post connections in 2022! Thanks again for the wealth of knowledge, Howard.
Happy to help. Please promote the website by subscribing.
Thanks - very useful into. Going thru EBB process right now for my house and this was an option that my contractor proposed. I rejected it since it wasn't required and also thought its something I could easily do myself. However watching this video, it basically means I don't need to do it and its not needed.
That is right, if I had a quarter for every unnecessary piece of hardware I have seen under houses I could spend all day making videos. Please do me a favor and subscribe.
This is fascinating. I worked for a contractor in the mid-90's and we did retrofits in the East Bay. I specifically recall asking if we shouldn't reinforce the posts, beams and pier blocks and being told exactly this. Better to spend the money on the perimeter, foundation, tying to that, shear walls, etc...
Now you know why
Wow, thanks for this video. We recently saw a house where the owners spent a lot of money on those T-straps for the post and beams. The foundation contractor also applied carbon fiber to the perimeter concrete stem wall foundations. In a report, the contractor wrote that the stem wall concrete surface material was ground down and cleaned before the carbon fiber was applied. However, because the retrofit was done without a permit, it's not clear what kinds of inspections this foundation retrofit passed.
Is carbon fiber an approved code compliant method to strengthen an old deteriorated concrete stem foundation wall of a one-story single family home? What kinds of inspections, if any, are required prior to and/or subsequent to application?
Thank you for a clear and informative video on this. Would be interested in seeing a video on bolting down a house after lifting it and then putting it back down on a new foundation.
I am going to need to leave that video to you. Good idea!
thank you for the heads up, your videos saved me from making a stupid purchase
Glad I could help. Please be sure and subscribe.
great video, what about old underfloor that have 3',4' posts supporting etc ..bracing does help
Your video made me feel better about my post to beam connections on my deck . 2 levels , 38 years old , southern cal , all Doug Fir . Rim beams are 4X 10 X 16’ connected to 8X8 20’ post with 1” through bolts and or lags.
There are a lot of videos talking about that connection should never rely on shear strength of 2 bolts. I’m assuming when it was built it was code. It may still be ? Thanks for the video .
I have the same type of deck but less lumber. 6x6 with one 2x10 rim. I think if you add a Deck Joist Tie you'll sleep better at night. That basically will make your connection the same as beam on post
Hi. Very clear video. I was hoping at the end that you would show what type of connection or bracing is necessary for an older foundation where the piers are merely siting on top of a concrete block and not currently connected at either the top or bottom. Thanks.
Can you send me a photo of what you are talking about? The code says only one nail is required at the bottom. Type in "Post to Beam" in the search bar and you will see the code citation on the webpage. I thought this was included in the video.
@@bayarearetrofit5814 Great video and I also hoped that you'd provide an image of the right nail connection that you are referring to.
Toe Nails
@@bayarearetrofit5814 Thanks
Happy to help. If you could subscribe I would appreciate it.
What are steel plate shims?
I have brick walls on top of a brick foundation and the floor is held up by posts like this. I am lifting/leveling the floor joists and was going to replace the floor beams and posts and add metal hardware like in this video. I see what you mean about that hardware being worthless, but in my case I don't know how to securely attach the house to the brick foundation since brick seems fragile. Instead of posts holding up the floor should I put shear walls under the floor and hope that also adds stability to the brick structure?
Sorry I am so late in my reply. I do not know UA-cam did not notify me about your comment. Look at my webpage on brick foundations.
Wow, thank you! I was thinking of spending a bunch of money to put a third beam under my house....no more!
Nice video. I just put upside down triangle plywood over side of beam and post. Not sure what happens when the big one comes and ground give way.
When looking in my crawl space I noticed that several posts have almost completely slid off their pier blocks. Is THAT something you'd recommend fixing? If not, I'd worry that my floor would start sagging from the lack of support...
I would say it does not matter in terms of resisting lateral earthquake forces but does matter as far as gravity goes.
I been upgrading my house and been using this metal plates anywhere I can. Probably keep doing it.
Do you have any videos pertaining to a stone foundations from southern california...I have a 100 year old house and the original foundation is still mostly there but slowly crumbling outward in areas? I would think retrofiting it would be an option?
On the homepage there is a video on old foundations. Your house has the equivalent of a crappy brick foundation.
The code says put a nail at the bottom of the post. Read the article. It also says the purpose of a connection here is simply to keep the post in place in the event someone kicks it by mistake. Everyone puts nails at the top and bottom of the post but you don't really need to per code.
What is done with older homes that are all post and beam? Is the house jacked up and a perimeter foundation added?
Yes
so good!
Yes, this video has saved a lot of people a lot of money.
Yes, and do a search on brick foundations. It contains an article I wrote that will help you.
Thank you, I will look at that.
Thank you for sharing, the question I have one can spend between 15K to 25K on building a deck but avoid securing it because gravity will play a big role so we can save between $500 to $2000
is it technically fair to say that you need x amount of material based on the size, height, and location (hot, cold weather)
There are too many unknown factors to give you an answer.
This is awesome but what should you do to maximize safety from earthquakes? I live right near one!
I was going to put on those Simpson ties so I won’t waste my money on these. I have beams supporting a 1-1/4” plywood floor so now floor joists. What should I do?
You should have 4 x 6 beams on the entire perimeter. Connect those to the sill with Simpson L90s, add URFP, make sure and engineer it with the info on the website, and call it a day. If you could post a YELP review that says some good things about the website and your experience with me it would be appreciated
@@howardcook35 many thanks Howard! I will do!
Is fixing the sinking perimeter walls enough or shall we combine attention on both …. I have the case in my crawlspace , the middle piers are kinda sinking not because the soil is softer there but precisely at the bottom of the perimeter foundation walls sinking or tilting cause of water badly diverted around the house foundation walls on which each end of the main girder is sitting. So the support sinking the girder is kind of sliding out of its place n push down on the piers supporting it in the middle .. question is how do you get the perimeter walls issue fixed … I mean once the job of getting the rain water away from the house ? Please give us some guidance there your video threw all my courage down into the deepest spot of the crawl space
The only thing I know is to level the floor. To do it right you need to use a laser. Maybe there is something on UA-cam. I have never done it myself. If you discover anything let me know.
You can use a water level to level the floor. Get 100' of 3/8" or 1/2" vinyl tube and fill it with water. Attach it to two sticks, stakes, or rods. Place one of these against a door frame solidly with the bottom resting on the floor. Do not let it move. Then go around the house and measure the level of water from the floor to the level point. You can then build a map of where your floor is out of level. I will be doing this in my south bay area home built on expansive clay soil in the coming year.
It would be helpful to have a link to the proper way to do so.
There is no reason to learn how to properly do something that does not need to be done. Watch the video and read the code citation one more time.
Is the leaning post something worry about?
No, not at all. Sometimes contractors put the concrete pier block in the wrong place such that it is not directly under the beam. When this happens they need to put the post in at an angle so that the beam is supported. I used to do a lot of structural work not related to retrofitting and know from experience that if you remove a few posts you won't even notice it except the floor might have a little more bounce in that area.
Foundation Retro fit is recommended in California especially if your home was built before 1930-1940.
Working under an older house to level it was not a favorite thing that I have done. You start jacking up the house and it starts creaking and cracking. Very nerve-wracking. Get the steel plate shims in and get out.
So what exactly SHOULD you do for a seismic retrofit?
I was confused also because he gave all the examples about how not to do it and waste money, but he never stated the correct way to do it and engineers just don’t design to design. Please advise.
I agree! I have a 16' beam through the center of the house sitting on two posts, each post made of 3 - 2x6"s nailed together. I'm worried that lateral movement and shaking could knock the beam off the posts and was hoping to see if there was a way to shore the posts up to the floor joists. If the beam falls off the posts in a quake, the house and roof will cave in.
I got EBB approved recently. I was only going to install the universal retrofit foundation plates per code and thought that would be sufficient. However, watching several UA-cam videos it looks like code also requires upgrading mud sill bolts on older homes (mine was built in 1965) and drilling vent holes in cripple wall plywood and would like to know if that’s accurate.
Thank Donald
The EBB requires that you use either FEMA P-1100 or Standard Plan A to qualify for the grant. You can find a comparison between the two systems on this webpage.
bayarearetrofit.com/fema-p-1100-icc-1300-and-standard-plan-a/
Please study this webpage so that you know which system you want to use. This is an important decision and will make a big difference in terms of cost.
If everything strapped up to the floor joists, wouldn’t it provide some resist from the home flying off the permitter?
Also, if strapped wouldn’t it add support against cripple wall failure? Not trying to be a contrarian, genuinely trying to understand. I’m a DIY’er with an old home.
There are two types of earthquake faults, thrust faults and lateral-slip faults. The Hayward Fault is a thrust fault. Thrust faults have a vertical component. The building code does not recognize this force as being something you need to resist, though Simpson StrongTie likes for people to believe otherwise so they can sell more hardware. Houses move up with the ground and down with the ground. They do do not become separated because of upward acceleration. That is why building codes do not address vertical acceleration. Hope that helped. If you haven't done so, please subscribe.
Bay Area Seismic Retrofit So you are saying that houses do not bounce and there is no need to add vertical connection from the beams to the post to the pier? A single nail from 100 years ago placed at the bottom is adequate? Genuine question, I wasn’t aware vertical acceleration is not of concern.
Many faults, such as the Hayward Fault, are thrust faults which means there is a vertical component. However, the building code a observed evidence do not see this as a source of damage. The building code only requires exactly what you describe. I personally would add a few nails to the top and the bottom "well, .....just because" as the structural engineer who helped me put that video together expressed it.
Interesting video. I have a question though. When you say "one nail", where would that nail go? Probably a dumb question, but I can't picture the answer.
It says at the bottom of the post. Read it again.
I had the same question. A nail into the bottom of a wood post into what, the cement pier? Those L shape straps seem simple enough, my posts are half hanging off the piers.
Just curious what city building code this is?
International Residential Code
well, here's the rub... in remodeling a bathroom, an engineer is sometimes required by the city in order to sign off on the permit. The engineer makes calculations and requires / specifies Simpson-Tie post connectors (the AC4) like the ones shown here which you consider unnecessary. As a homeowner without an engineering degree, how does one combat the engineer's recommendation in order for the city to sign off on the permit? I am of the mind to just lock everything in under the house since no one knows the direction and type of earthquake that's coming. The AC4 and hurricane connectors are relatively cheap and require a little elbow grease under the house.
Fighting with an engineer is a waste of breath. You can cite the code which you find on the webpage but they won't listen. Your idea is a good one.
You mention that post and beam connections are not a proven retrofit technique - this uses a crawl space as an example. Does also apply to soft-story conditions where there are fewer total posts? (first story garage with crawl space > 7 feet).
The same principles apply, though in my opinion the posts could be dislodged from the shaking itself regardless of whether or not the floor moved. It is so cheap to strengthen this connection, even a few nails ought to do it, why take the chance? Especially when you have a limited number of posts.
@@bayarearetrofit5814 Sure makes sense regarding nails, why not? How about other recommendations such as far as adding hardware connectors / improving concrete footing?
Leave the concrete alone. Search for SEAOSC and as far as the rest of it, it is all important.
I am happy to hear it helped you. Because they see some stupid engineer recommend them.
Look at my video on Standard Plan A, which is what you will need to use. Once you see it you will probably decide to do something else.
Maybe the supports were installed for support purposes only and not for seismic retrofitting.
A lot of houses that were built a long time ago may require additional support over time. Personally I feel the photos were used out of context to make the video, since the drawings or plans do not mention for seismic activity but they also do not mention for structural support. I would think you need some type of shock absorbers or the house to be on rollers to handle serious seismic activity. Posts or no post are not going to save the house from an earthquake. The perimeter of the house would be more important than the middle when it comes to seismic activity.
Please go to bayarearetrofit.com and search for "post to beam" and read the code requirement.
Even though this is not required by IEBC it is recommended by Simpson Strong in their 2019 Seismic Retrofit guide for raised foundations under section AC Post Caps and loads are actually available on the specs sheet. So it is NOT a waste of money
It is important to remember that Simpson is in the business of selling hardware, not public safety or spending people's money wisely. Their plan set and guide has other recommendations that are not logical, but they do increase hardware consumption. Impartial agencies such as the ICC are not trying to sell anything. In the end one must listen to both sides, see which is the most logical, and act from there.
This is like the oil companies saying that you need to replace the oil every 5k. Or the umbrella company saying to replace your umbrella every 5 raining seasons.
You’re joking. Right?
Sounds like it will work to me
I am confused????! You gave all the examples about how not to do it and waste money, but he never stated the correct way to do it, and engineers just don’t design to design. Please advise.
Why show a correct way to do it when there is no reason to do it. It is hard to imagine a correct way to do something that does not need to be done.
Plenty of engineers design things just to design. If not, half of them would be out of work…
The building code is the building code so I dunno!
I don't understand why this is a complete waste. Your other videos show the importance of preventing shear, uplift, etc by building shear walls. Are you saying shear walls are all that's important, that they will take the force instead of these posts and beams? It seems like the hardware you are saying is a waste would help prevent some shear force? thanks. Great videos.
A post provides zero lateral resistance. Imagine the floor sitting on top of the post and the floor happens to move a foot, the post will tip over. If the house remains secured to the foundation the floor will not move on top of the posts at all and the posts will not tip over. In other words, if you secure the house to the foundation on the perimeter the floor will not move on top of the the posts don't need to resist anything. The metal post connectors you are referring to have ZERO lateral resistance according to the manufacturer. Why put in hardware that is labor intensive, is not required by the code, and offers zero lateral resistance? If the post is required to resist lateral force because the house has become disconnected from the foundation you are screwed anyway. Best to spend your money where it counts.
@@bayarearetrofit5814 got it. Okay that helps-visualizing that everything will move together as long as the walls in the foundation are strong and properly done. Thanks, great videos.
Ask anything, anytime.
I was confused also because he gave all the examples about how not to do it and waste money, but he never stated the correct way to do it and engineers just don’t design to design. Please advise.
@@tyrice24earl check out his many other vids. He covers the important stuff about proper installations and recommendations there.
I watched the video from beginning to end, and What I took away from that was his recommendation to use nothing to attach the post to concrete, and post to beam. I do not think you would ever get a occupation permit following his logic, right or wrong. 🤔
Yes you would. You are following the code.
...and!...."resist-ant-to-Earth-quake?!... "...Hmm?!... So, why not then think about de-signing "Rocking"..., "Jumping"...and "Swinging" "Building-Design-Structures"!?.....Nyet.. ?!...I, I don't know!....Im-possible?!.....😃
Is just a waste money
all the criticism yet no answer provided.
This subject is very technical for most people and speaking slowly is helpful.
There is an answer. It is not worth bothering with. Why fix it if it ain't broke? Why address a problem that is not a problem? Why do you think this connection is a failure point?
What is the failure point and how to properly address the failure point?
@@tmaila there isn't a failure point
I hear you state your conclusion that the examples you show are "useless" and a "complete waste of money", but can you include a link or provide the evidence for what you believe is useful?
Anything that will keep the post up when you kick it, which is just about anything. Please read the information on the webpage at bayarearetrofit.com/post-beam-connection/
Thanks! @@bayarearetrofit5814
...and!...."Shock-Absorbers" can help?!....😃
I see your point as it is related directly to seismic or 'lateral' loading incidents. However, you are leaving out two additional VERY important types of loading conditions...The first is due to soil movement (shrink/swell) and the second is wind uplift anchorage. These connections are instrumental in aiding in structural stability of the home during those two types of loading conditions. To tell people that the engineers are simply "not educated" enough and just spec these connections because they are uninformed is a bit dangerous on your part. Especially given the fact that you didn't even mention these additional loading conditions...It is the engineer's job to think through and design for ALL possible future loading conditions. IF you are going to make a video spreading misinformation, maybe you should be able to disprove the need for those connections ( after applying all loading conditions) mathematically. IF you cannot, you are not qualified and you should simply not speak on these matters. Also, I will remind you that the IRC code is the MINIMUM spec allowable. It should not be looked at as the end all/be all for construction. It was created to give the contractor and homeowner information on the absolute MINIMUM safe design conditions.
I see your point as it is related directly to seismic or 'lateral' loading incidents. However, you are leaving out two additional VERY important types of loading conditions...The first is due to soil movement (shrink/swell) and the second is wind uplift anchorage. These connections are instrumental in aiding in structural stability of the home during those two types of loading conditions.
I live in an area that is almost entirely unconsolidated soil that shrinks and swells as you describe and have never seen a post connection come apart even the least bit.
To tell people that the engineers are simply "not educated" enough and just spec these connections because they are uninformed is a bit dangerous on your part. Especially given the fact that you didn't even mention these additional loading conditions.
How are a few nails or even steel straps going to prevent a house from lifting up off its foundation? We do not see this kind of damage in earthquake county, at least I am not aware of any. From my point of view building codes inform engineers and contractors which connections are important, and this isn't one.
..It is the engineer's job to think through and design for ALL possible future loading conditions. IF you are going to make a video spreading misinformation, maybe you should be able to disprove the need for those connections ( after applying all loading conditions) mathematically.
I do not look at theoretical/mathematical conjecture. I look at empirical evidence and also hope that the authors of the building code did the same. If you can find ONE photo of failure to a post beam connection due to soil displacement I will point that out because I have some empirical evidence to back it up. If you can find another photo with wind damage that would also be helpful.
IF you cannot, you are not qualified and you should simply not speak on these matters. Also, I will remind you that the IRC code is the MINIMUM spec allowable. It should not be looked at as the end all/be all for construction. It was created to give the contractor and homeowner information on the absolute MINIMUM safe design conditions.
And it should be based on a MINIMUM amount of empirical evidence and I don't see any. Also, in seismic retrofits one must also look at the math in terms of spending their money wisely and cost-effectively. Really, please send me photos, not math formulas, of the two types of failure modes you mentioned, that occurred in earthquake country. I am always eager to update my site and provide accurate, evidence based, information.
Theese enginners loves money
Contractors too!
All this talks about is what NOT TO DO, how about WHAT TO DO ???
You missed the point. THERE IS NOTHING TO DO.
I disagree with you on many of your observations
Great! Let me know what you disagree with on each video you disagree with and we can have a conversation.
I would not use you. You do too many cut backs. You remind me of Surfside.
Not helpful at all cause you’re developing above n beyond the wrong done communally done by lots of contractors under guidance of structural engineers but you’re not giving us a clue of how to address failing piers on old houses if not this way … at least if you have it give us an alternative so that we can learn how to address this issue better… thank you
What do you mean by failing?
The video spends most of it's time showing what is a waste of money while failing to show the right way to do it.
The right way is to follow the code which is illustrated in the video. Watch it again.
would have helped more if you showed the CORRECT way to do it and not shighting on others work
I quoted the code. It is up to the reader to decide if I am shitting on other people's work.