Connecting Joists to New LVLs
casabian
| Posted in General Questions on
First time renovating, and hoping I can use GBA as a sort of check on my contractor’s work and to learn.
Attached is a picture of recently hung joists (they were sistered to exiting joist and connected to a new LVL).
My question is about the space I see between the hangers and the joists. Is this normal? Or poor workmanship?
For context, we lifted the house off the old foundation to pour a new foundation.
Thank you!
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Replies
The double joist that lands on the hanger that is mounted to a ledger seems like too large a gap. The hanger manufacturers rate the hangers for a certain maximum gap. Consult documentation for specifics, but it's probably around 1/8" for full rating.
Also, I hope that ledger is temporary and that there's a plan to mount a full height layer, connected appropriately using fasteners to handle the design load of that lamination.
The fact that the current ledger is not the full height means those hangers are not properly secured.
I also don't love that all three LVL plys are jointed at what I'm presuming is a column location. It would be nice if the LVLs were longer.
Looks like the joists were cut a bit short. To me, it looks like they might have been eyeballed and not measured, resulting in the random variation between joists. The smaller gaps probably aren’t a problem but it’s worth checking with the hanger manufacturer.
The joists tied in at the lower part of the pic where a too-narrow piece of 2x was used to tie the LVLs together ARE a problem. The hangers aren’t supposed to be in free-air on the top as they are (due to the board being less than the height of the LVLs), and the one up from the bottom has one of the two joists so short that I doubt the nails are even really grabbing it at the end. Those need to be dealt with.
I agree the LVLs are not jointed very well. Usually they tell you to use LVLs twice (or more) the span between columns, then stagger the joints so not all LVL ends land on the same column. You get a weaker joint when all the ends line up. I would probably strap a piece of LVL over each side of the triple beam there and bolt it to rectify. It might be worth asking an engineer on that particular joint to play it safe.
Bill
This is an ugly sight, there's no doubt about it. HOWEVER, as a remodeling contractor myself, if I were your contractor I would very much appreciate the chance to defend my construction decisions. Sometimes there are horrendous issues of access or structural considerations that aren't immediately obvious to the observer. Sometimes ugly workmanship is actually part of previous work. Sometimes we'll way overengineer or overbuild a solution, simply because it's cheaper in labor or materials or both. One unfortunate route is to leave something substandard for the same reason.
All that said, the three LVL's would definitely be better with staggered joints. There's a right way to install a joist hanger, any deviation results in a de-rating, unless it's so bad that it probably should be redone, as is the case in the second from the bottom. You've got a LOT of seat-of-the-pants structural modification going on--it would be better if you had confidence in your builder. A word of caution: this kind of stuff is VERY difficult to inspect and evaluate over the internet.
If you are having an inspector look at this, then you won't have to be the bad guy. But if yours is like most jobsites, that's not going to happen and you'll have to be delicate with your discussions with your builder. Educate yourself, as you're doing; then give your builder the chance to explain himself; it could be when he finds out you care and are willing to pay to have it done right, he'll be relieved to fix it. If you're still not happy after all this, then play hardball. Nicely. Good luck!!
Assuming that the double joists are there to re-inforce existing rotten joists, not because of structural reasons, you really only need one of the pair is fully supported, which seems to be the case.
The ledger is definitely not a good thing but since our code allows for joists to be supported by a ledger with the correct nail schedule (ours is 2x 12D nails per joist), there is nothing inherently wrong with it. Definitely not pretty though.
As for the LVL joint above the column, that is fine provided the engineer spec it as a simple span (how it is specked 99% of the time). You do get significantly less deflection by having the LVL continuous span and since LVLs here are sold by the foot, there is no reason to use shorties instead of full length ones. I've had no issues getting 30' delivered.
The one problem you might have, which I would run by the engineer is it looks like the LVL is side loaded. In this situation, spacing the floor joists off the LVL with the ledger could be a problem as it causes the beam to twist more.
>"Assuming that the double joists are there to re-inforce existing rotten joists, not because of structural reasons, you really only need one of the pair is fully supported, which seems to be the case."
I've run into that before, and there IS one common issue when sistering joists to deal with rot/splits, and using hangers: hangers intended for two joists MUST be filled with two "joists". If they are not filled, the hanger can deform (the lower saddle part can bow downwards and pull the two sides inward). If you're dealing with an old/rotten/etc joist, you just need to put a piece of blocking in the hanger on the end to make sure there is something solid to keep the hanger from deforming.
Joist hangers are pretty specific as to how they have to be installed, and you really can't deviate from the design if you want the hanger to hold.
Bill
Thank you all. Definitely working on getting the vocabulary for all of this. What a great resource to be able to learn. I added an updated photo from the work site.
@Patrick - I spoke with the builder and he said the ledger was not temporary, that there would be a piece that went on top of it. You are correct that the LVLs are jointed at a column location.
@Zephyr and Patrick - do you think another piece of wood mounted on top will rectify the problem of them being "free-air"
@Andy - thank you for your note and caution about evaluating things like this over the internet. There are definitely many previous mistakes that were made in building this house. I like my contractor a lot as a person...very communicative and always willing to explain things. That said, it concerns me that he didn't see the second from the bottom joist as a problem.
Finally, @akos, you are right that the double joists are sistered to reinforce rotten joists. How can I ascertain if the LVLs are side loaded? My GC is the one who hired the engineer. I do have the plans if that's something people would want to look at.
Any further advice is greatly appreciated!
>"@Zephyr and Patrick - do you think another piece of wood mounted on top will rectify the problem of them being "free-air""
No, it will not. The load is in the vertical plane, which is along the long axis of the joist. A piece "on top" won't really do much. The easiest solution is to either use a steel bracket here (if you can find one, you'd probably have to have it made), or replace the single 2x with a double to bring the hanger out a bit, then bolt those into the LVL (which you'll want to clear with your engineer).
Your engineer, even if the GC was the retaining the engineer, is the one to ask about the loading on that LVL. That engineer can also spec a brace for that joint with the three ends all lined up.
Bill
A beam has unbalanced side load when there are only joists on one side of it. This can cause the beam to rotate. See Fig 1 here for details:
https://www.weyerhaeuser.com/blog/wood-beam-design-and-installation-considerations/
In your case, it looks like that is the case, that is why I mentioned to check with the engineer. The wider the beam the more it will tend to rotate under load, thus spacing the joists out is problematic.
> @Zephyr and Patrick - do you think another piece of wood mounted on top will rectify the problem of them being "free-air"
Depends on your definition of 'rectify'. Is this thing alone enough to cause the house to fall down? Likely not. Is a strip on top of that undersized ledger the correct fix? No. It might even be hard for an engineer to sign off on it because of lack of derated values on the hangers for that specific odd configuration.
Not clear why that ledger was undersized in the first place. Perhaps it was to slip it into place underneath something 'to the right' (as oriented in the second photo). If that's the case though, a nicer thing to do is get a piece of LVL that's as deep as the largest dimension you need, then rip it to fit into the smaller area as needed.
I get particularly annoyed with sloppy work in areas like this because I feel it tends to be an indicator of overall attention to detail. That said... the fact that there is an engineer involved here is a good indicator that the GC wants to do a good job overall. Make sure the engineer inspects and approves anything that's part of their scope.
That triple LVL beam heading upwards in your second photo, presumably hung with a proper hanger or bracket on the main triple LVL, opposite the sistered joists, will counteract the twisting force of the joists. The post to the floor below, holding this point up, will need to either be a big timber beam or some kind of gigantic customized steel number.
But there's a lot more going on in the periphery of what we can see. That upward LVL beam cuts completely through a big wood sill beam of some sort. Are the loads properly reconfigured from THAT mod???
>"or some kind of gigantic customized steel number."
Probably a 3" column would do. I work with steel a lot at work, and it's surprising how much a steel column can hold, especially if it's not very tall. Steel's main advantage in residential construction is it's ability to handle heavy loads in a smaller area than wood, and to support longer unsupported spans.
Bill
Yes, a basic steel column will do, but to be clear I was referring to its flange or bearing surface, and how the various beams are anchored to it.
Ah, not quite what I'd thought :-)
They make steel saddles to hold large LVL beams that help to spread the load over a larger area of the wooden surface of the beam. I think these saddles are required by code now in many cases (not sure on that though).
Bill
That looks like a sloppy joe. Not to mention where's your vapor barrier down below.
That looks like a sloppy joe. Not to mention where's your vapor barrier down below.