LVLS sitting on Pressure Treated Wood
casabian
| Posted in General Questions on
Hi all,
My contractor who I have since stopped working with installed the LVLs as pictured. Multiple people have expressed concern because the wood (some is not pressure treated) will expand and contract but wanted to check with this knowledgeable group.
If it needs to be changed, what material would you recommend or the shim?
There’s another spot where he did the same thing.
Thanks as always.
Ed
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That's not generally a good practice, both because of expansion/contraction, and also because the wood will slightly crush over time. Not a super big deal, and will probably stabilize over time, though you might notice some bumps in the floors. That stack might be tall enough to fit a pancake masonry block or two in that space, or brick - that would be the standard treatment. If you do that, you still need a steel plate or other moisture barrier to prevent moisture from wicking into the wood beams. Or you could use a stack of steel plates. Or you could use a section of steel box beam (engineered for load). Basically, you want something effectively incompressible. There are other options.
That's a bit of a hack job, but probably not really a safety issue. At least they used treated lumber where it's in contact with the masonry. That's like saying "see, I know what I'm doing, I just didn't care that much today".
I would try one of two options, since that really isn't a proper support. Either try to cut a piece of precast block to fit the gap, then use only ONE treated block above it, or have a structural steel fabricator weld you up a bearing plate assembly with two flat steel plates (bottom and top) and some tube in between (3" tube with 1/4" wall is pretty typical). It's probably under $100 to get this made. I'd probably use 3/8" steel plate for the top and bottom, which is a bit of overkill, but ensures you don't have any deflection issues.
If you have a steel piece made, BE SURE to have them prime it before you get it. I'd then put a coat of Rustoleum's "stops rust" high performance enamel over the primer. I like to use "gloss smoke gray" for this kind of thing. Once you've done that, the piece will last forever without getting rusty. Have them punch a hole or two in the top and bottom plates so that you can pin the assembly in place once installed too.
Bill
Is there a detail on the drawings that show the number/ type of bolts needed to secure the LVL to the concrete or is it blocks?
I'd think they need to be through bolted or sit in a U shape bracket that is bolted down.
Are those 2x4 on their sides the entire bearing of the LVL?
Do you have any idea why the block is notched? Looks like maybe the LVL was installed from below and they had to notch it to get it up in there?
Steel may stop ground moisture wicking up through the foundation from migrating into the LVL, but steel itself will condensate with moisture.
I'd figure out the answer to the above two issues, and try to figure out a way to get the LVL have more bearing surface on the concrete pier. My choice of stack going up would be:
- Solid concrete with a few pieces of threaded rod sticking up through it.
- Peel and stick moisture barrier, or if you are in a region that has termites, something like Term Barrier. Although I would not buy an entire roll of it to use 1 sf. Someone has something you can use. Poke holes where the threaded rod is, and put waterproof goop around those.
- Treated 2x8, on it's side, with holes drilled for the threaded rods
- 2x8 secured to foundation with bolts through the threaded rods
- LVL bearing on and secured to the 2x8. I'd look at the framing drawings for the minimum surface area of bearing.
What bothers me about the photo is it looks like there is a hanger for the LVLs to be "hung" from an existing 2x's with a new 2x sistered to it, but the LVL is also bearing on the pier. Which is it supposed to be? And why is the Advantec notched above?
Also, this looks more like a triple LVL.
Whether the blocks are large enough depends on how much load they are carrying. Face-grain framing lumber can support up to 350-400 lbs/in² without crushing. If the load is more than that you need more bearing area or blocking that has greater resistance to crushing. What you have looks sloppy but the floor system is held in place at the perimeter and I don't see anything inherently wrong.
I'm not an expert...but I have had a similar set-up in my house in several places for over 20 years now with no problem. The blocks did crush a bit but to no obvious effect.
Do you know why that recess in the concrete was put there? Your bigger issue may be that it was put there for something else, and that something was never done. Or is this renovation?
I am suspicious about that recess too. Looks like it was made to accept a recessed P-Lam girder. Do you have the drawings to confirm why that is there?
This is renovation, but a new foundation. Someone else originally spec’d it for a larger girder, but then got an engineer who did the drawings with the LVL pictured.
Trying to decide if it’s worth the time and effort to jack it up and change out the wood.
Thanks for everyone’s input.
If there isn't too much weight on it, should be very easy to jack. Replace some of the 2x lumber with brick/CMU, keep only the wood that is needed to shim it tight. Make sure there is poly between the brick and the shim. Always best to shim with plywood, not lumber. Solid, never have to worry about settling down the road.
Depending on your local code that beam might need to be anchored to the foundation as well, simplest is something like a Simpson FJA.
Assuming the wall is poured concrete (can't be sure from the photo), there is nothing inherently wrong with this. But as others have said it's definitely a hack job. I've seen worse, and I've seen better. The bottom shim is PT so that's good. As for movement, your whole house will move over time.
If it bothers you enough to change it, replace with a chunk of 6x6 PT timber that fits in the concrete slot, so all sides can snug up to the concrete. Then shim with whatever is required.
I'd be more concerned that the original beam looks like it was substantially deeper than the current LVL beam. Or did the contractor cut this notch and make a mistake? Even though this is 3 ply LVL, that's a lot of depth reduction. I have no idea what the original framing was, but I'd make sure the LVL was designed correctly and matches what is on the approved drawings.