Two 2x4s as pier support in pier and beam crawlspace

I tried to search previous posts but couldn’t get a clear definitive answer on this. Are two 2x4s nailed together allowed as a pier support in a crawlspace pier and beam foundation ? Isn’t a 4x4 the required minimum? Two 2x4s are 3x3.5 and not 3.5x3.5 like a proper 4x4. I saw this in two houses I did for practice inspections where every single pier/post was configured with 2 2x4s nailed together to create a post.

That sounds simply inadequate, Alex! :smile:

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Pretty sure the minimum is 6x6.

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My apologies. I didn’t answer Alex’s question.

Darren, I believe you are correct at 6" x 6".

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Does it also depends on how closely the piers/posts are spaced? The first house the piers and posts were spaced super close to each other. It appeared to be more pier/posts than typical. I was not able to access the crawlspace - very tight and a duct across the access opening :roll_eyes: face palm. The (2) 2x4 “posts” that I saw didn’t appear to show any signs of failure. I really thought I had a picture - it’s my neighbor’s house and I could still get one

Typically, the posts are about 6’ apart. After that, it becomes a judgement call. Are there other anomalies that come into play? e.g. are the posts on and connected to footings and connected to the beam at each location? they lean?..are the separating?, etc.

If all looks good, you will want to mention that common building practices use a minimum of 6" x 6" posts and these are not sized as such and to monitor for any future movement when replacement may be necessary. :smile:

Okay sounds good. I still have a lot of structural review left to do. I thought I had read that 4x4s were minimum but maybe that was just for decks? …The “posts” for this crawlspace were definitely closer than 6 feet. Even if I could get into the crawlspace, it looked very difficult to navigate. Lol

What do you recommend as a good resource/document for furthering my education on foundations? I don’t think the AHIT course was sufficient for all that I need to know.

Since there were so many close together, are you sure they weren’t added for additional support?

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Don’t know off hand, Alex.

Maybe I could send a copy of my noodle? :joy:

It doesn’t sound like it was engineered, though you are correct with mostly larger columns. :smile:

It didn’t appear so. I looked like all of the posts were two 2x4s nailed together. Nails were rusty - should have been PT regardless.

You’re in Oregon, yes?

And I see 4x4 posts all the time. Often in brand new homes (usually 4x6 at seams in the girder). I do not believe that 6x6 is the minimum. The girders are generally 4x8. Having a hard time finding a definitive answer in the IRC/ORSC. PT is only required if the framing is less than 8" from grade.

So just read an article that says plies of dimensional lumber can be used for posts. Still though, with my engineering background, my gut says to at least say to monitor even if everything else looks good because mechanically 2 pieces of wood nailed together don’t have the same strength as 1 piece of the same size. In pure axial compresson, which would never be reality, vertical loads only, it seems okay. But in bending, if lateral force is applied in wind or earthquake scenarios, bending strength of one ply would not be transfered to the next ply unless say the two plies are glued to together as with engineered lumber. The nailing schedule would have to be really really smart to make an apples to apples comparison. This guy on jlc seems to make a good argument: 15818989632688778374519306045312|375x500

Good gut and good read, Alex. Thanks! :smile:

Alexandra, you have a good grasp of what is going on. Great job!

Haha thanks, I had to refresh a little on the subject. Structural design was never my strong suit in school, I preferred water resources and grading. Lol

Thanks Charley! I need to remember to go back to code when I wonder about these things. I looked you up - you’re in Portland right? I’m in southern oregon. Any chance you would let me shadow you for an inspection? Even though I have my license and have had a few shadows, I feel like a should get in one or two more before I start inspecting for real. I will be up in the Portland area March 14th and 15th (sat and sun) - I don’t know if you do weekend inspections…just a shot in the dark lol

I no longer do weekend inspections. I have an 11 month old at home and spend my weekends with my family. And while I’d like to help, I’m hesitant to have additional bodies around while I inspect. I don’t know, maybe I have a short attention span, but I’m easily distracted. Happy to answer questions though!

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No worries, I get it. I feel like I would all over the place if someone were to shadow me. Nice to talk to another Oregon inspector! :grin: