Reinforcing lvl

skruis

I'm not sure what to do here...

I recently had a new garage put in with an upstairs loft which will eventually become my office. The garage is 24'x24'. The builder used a pair of 2"x12"x24' LVLs nailed together as the support beam for the floor joists. I can be standing on the upstairs floor and notice some bounce when my 75lb dog walks around...its unnacceptable.

He's come up with a couple of solutions...

1) He says he can add 2 more LVL's of 2"x16"x24' to make it stiffer

-or-

2) He says he can put a series of steel plates on both sides of the existing LVL's to stiff it up so that I can save headroom.

What do you guys think?

Thanks,

Sean

buletbob

I'm in the process of building a 960sf garage for a customer, we have a span of 24ft.carring a roof load and floor load. and the Engineer spec. out a girder of three 14" LVL's with two 1/2" x 14" steel plates sandwiched in between, You must consult with and engineer so he can calculate the loads. BOB

DangerMouse

when i put in the doubled up 2"x12"x20' lvls in the new dining room addition, my engineer had me use 1/2" bolts thru every 2' OC staggered up and down the run at 2 1/2 inches from the top then bottom. i should think nails would allow too much shifting.
i agree with bob to have an engineer/architect do the math, but if you cannot do that, then maybe just one more lvl bolted tight will stop the movement? seems to me steel would be quite expensive, (as if lvl isn't! lol)
and heavier and harder to work with. i think the bolts will help stop the movement. perhaps you could try them alone first (get them 2" longer than needed) bolt what you have tight and see if it helps, if not enough, add the extra lvl and rebolt and see? i am not a contractor/builder or anything, just trying to help from my own experience. hope this helps!
DM

Termite

The fastening of the LVL's is not the issue here. Bolts are not required for three or less plies of 1-3/4" LVL. Nails are more than adequate, provided the nail pattern recommended by the manufacturer is followed. Bolts are required on four or more plies, and is overkill (that's not a bad thing) on two or three plies.

Two 11-7/8" LVL's spanning 24' with floor load is not anywhere near good enough, as you've obviously determined.

What I'd require is that your builder consult a structural engineer. He should have done that in the first place. The addition of steel flitch plates to the existing LVL's with bolts would stiffen them, but the question is how much will it stiffen them. 24' is a long way for a 11-7/8" floor-loaded wood floor beam to span, and I suspect that it won't be good enough.

Something that you should explore is the installation of a steel beam beneath the existing LVL's. An engineer can size a beam to take the deflection out of the LVL, and it will definately save you some headroom as opposed to adding two 16" LVL's.

Was there a permit on the job? What do the plans show? Was there an engineer, or did the guy design the structure on his own?