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Does attaching LVL headers together make them stronger? Meaning screwing/nailing or bolting them together.

I have been thinking about this for a few days off and on and keep going back and forth...
 

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diplomat
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I'm pretty sure 2 lvls are only twice as strong as one when calculated in, for example, BC calc, because they are already so many plies, there is no additional benefit. There may be added resistance to twisting, etc. in certain instances though.

Dimensional lumber might see more benefit, because the imperfections are less likely to overlap with multiple plies.

I happened to have a calc open in BC Calc while writing this, and doubling the LVL I was checking essentially halved its stress.
 

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Yes, fastening them together does increase their strength. When loaded from above, the laminated beam fastening schedule usually isn't too rigorous, as the load is usually spread evenly across the top. Then the beam is side-loaded (i.e. a joist hanger situation), the fastening schedule is very important to make the plies act as one member.
 

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I'm pretty sure 2 lvls are only twice as strong as one when calculated in, for example, BC calc, because they are already so many plies, there is no additional benefit. There may be added resistance to twisting, etc. in certain instances though.

Dimensional lumber might see more benefit, because the imperfections are less likely to overlap with multiple plies.

I happened to have a calc open in BC Calc while writing this, and doubling the LVL I was checking essentially halved its stress.
It probably depends on the loading direction. Two times as strong vertically, four times as stiff horizontally
 

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diplomat
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It probably depends on the loading direction. Two times as strong vertically, four times as stiff horizontally
If they are glued perfectly, closer to 8 times as stiff. Bending strength is the cube of the dimension.
 

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Carolina Surface Prep
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I'm pretty sure 2 lvls are only twice as strong as one when calculated in, for example, BC calc, because they are already so many plies, there is no additional benefit. There may be added resistance to twisting, etc. in certain instances though.

Dimensional lumber might see more benefit, because the imperfections are less likely to overlap with multiple plies.
Most accurate answer so far. There is a little additional benefit, but it is negligible when compared to the load capacities involved.

The fastener schedules are used to ensure the plies act as single cohesive member, especially when side loaded. The fasteners and glue you add don't make the plies any stronger, but they make sure all of the plies contribute their fair share to tote the load.
 

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Most accurate answer so far. There is a little additional benefit, but it is negligible when compared to the load capacities involved.

The fastener schedules are used to ensure the plies act as single cohesive member, especially when side loaded. The fasteners and glue you add don't make the plies any stronger, but they make sure all of the plies contribute their fair share to tote the load.
I have an lvl on a current job with another lvl hanging from it. We had bolts spec'd only at the area next to the hung member. I don't think I have seen this detail before. The rest of the lvl was just standard nailing.
 

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Carolina Surface Prep
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I have an lvl on a current job with another lvl hanging from it. We had bolts spec'd only at the area next to the hung member. I don't think I have seen this detail before. The rest of the lvl was just standard nailing.
The designer was ensuring the load from the hung member was transferred into all plies of the supporting beam. Once it's in there, the load won't jump back into just one ply. The rest of the beam only needed standard nailing to hold the plies together.

Also common with roof truss girders, but usually the many nails in the heavy framing connector provide the clustered fastener affect.
 

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The designer was ensuring the load from the hung member was transferred into all plies of the supporting beam. Once it's in there, the load won't jump back into just one ply. The rest of the beam only needed standard nailing to hold the plies together.

Also common with roof truss girders, but usually the many nails in the heavy framing connector provide the clustered fastener affect.
The hanger we had there had 60 16d nails in it. The funniest thing is that the hung member was a whopping 30 inches long.
 
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