Camber on Drag Truss

[mikedmiston]

Has anyone ever had a plan check engineer ask for the MIN camber on a drag truss?
Single family residence, and drag truss over parrallel shear wall. Plan Check Engineer wants Camber noted because "the specifications is very important for truss supplier furnishing that particular truss to meet the intention of designer." How does the Plan check engineer know what my intentions are?

Secondly, I'm curious to know what the consensus is on drag trusses bearing or non-bearing.
Feel free to respond.

Mike

 

[DaveAtkins]

The drag strut truss you describe cannot have any camber, because its bottom chord must be nailed at a close spacing to the top plate of the shear wall below.

DaveAtkins

 

[mikedmiston]

First,
Is it your opinion that this Plan Check Engineer wants camber in the truss because he wants the bot chord to be flush to the plate when loaded? and doesn't want the truss to deflect less than the others causing a lump in the roof?

Second,
I disagree. LPT5 connectors are meant to bend 1/2". If the connector is nailed to the bottom of the bottom chord of the truss and then nailed to the plate so the connector was flat, you can use it in a drag application, with the max 1/2" gap to the plate that non-bearing trusses should have. This is a standard detail on my plans.

And if you use the LPT5 in this manner, the ammount of deflection in the truss doesn't matter, you don't have to figure the camber because the truss does not need to be flush to the plate.

 

[STR04]

mikedmiston,

who makes this LPT5 connector? please describe.

TIA

 

[mikedmiston]

Sorry for the typ-o...it should be LTP5.
It's a framing anchor made by Simpson Strong Tie. It's like the LTP4 which is the old A35 Flat's. The LTP5 is designed to bend over the top of the shear panel to connect the ply to the block'g. Its rated at 630# which works out to 1 every 2 feet for a normal shear wall.