Multiple Ply LVL

[jeffhed]

I am working on a remodel project where the home owner wants to remove a column. The existing beam is (4) 16" LVL (although I don't see any bolts) that supports a roof ridge beam and a floor beam supporting a loft. If I remove the column the beam fails by 20% in deflection. However, if I add a 5th LVL ply the beam works. I was trained to never use more than four plies in a built up wood beam, but although I have looked multiple times I can't seem to find documentation on this requirement. It appears that it is some sort of rule of thumb at the very least because in Simpson's SDS literature and LVL literature they give fastening requirements for 2, 3 and 4 ply LVL built up beams. If I check the bolting for the 5 ply member, the bolts can transfer the required loads with every combination (1 LVL to 4 LVL and 2 LVL to 3 LVL). I can place extra bolts where the floor beam comes in to make sure the load is transferred to all 5 plies of the LVL. I can do this also where the stud pack is for the ridge beam. Can anyone tell me where the code does not allow more than 4 plies in a built up wood member? This would be a really simple retrofit if all the framer needs to do is add a 5th LVL ply to the existing beam and bolt them together.

Jeff

 

[JAE]

I don't think there is a code limit (could be mistaken but I've never seen anything like that).
It may be more of a practical limit as the width of the beam would get possibly difficult to properly support.

Think of it as two LVL beams - a two lam and a three lam each taking floor and roof load separately but just happening to be side-by-side.

Connecting them together gets you more redundancy in case of overload on one side or the other.



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[dik]

I'd add the next one, and, sleep comfortably... Not aware of any restrictions and have occasionally used 5 laminations...

Dik

 

[jeffhed]

Thank you, JAE and Dik for your replies. I was thinking along the same lines. It is probably some sort of rule of thumb. Calculations show it is good so I feel comfortable with adding the 5th ply structurally. Just wanted to be sure that there wasn't a good reason why I shouldn't add it.

 

[dhengr]

Jeffhed:
However, you should jack the existing 4-ply beam up, to essentially unload it (unstress it) before your install the 5th ply, and do the drilling and bolting. If you don’t do this, the 4-ply beam will carry its 80-90% of the load and some added deflection and bearing wood crushing will take place before the 5th ply starts to pick up its share of the load. This latter condition will over stress the 4-ply beam before the added ply comes into play.