Connections for Tall Heel Trusses
Originally published by: Builder Online — July 17, 2012
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The truss to shear wall connection is one of the most important links in the lateral force load path, but that extra heel height makes the connection a challenge.
When the wind howls or the earth shakes, roofs and walls must work together or the entire building can fold like a paperback novel. That’s because roofs are horizontal diaphragms that distribute lateral (wind and seismic) loads to walls, which, in turn, transfer them to the foundation.
When a structural failure occurs it’s usually a connection coming apart rather than the rupture of a beam, column, or other structural element. With stick-framed construction, the two most notorious connection failures are the roof to wall, and the floor to foundation.
Building codes are thorough at describing the forces involved but sketchy at best when it comes to detailing it all out. Here are three methods (slideshow) to ensure positive load transfer at a tall heel truss.
In this method, a tall block of LSL, LVL, or 2x is placed between each truss. The roof diaphragm is edge nailed to the block, and the truss bottom chord is connected to the shear wall with a hurricane clip. Vent holes may be notched or drilled into the block as necessary.
In this case, the connection is made by the wall sheathing itself. If the sheathing is continuous over the truss/top plate intersection, as shown, a hurricane clip is not needed. This method requires a block large enough to be edge nailed to both the roof sheathing and the wall sheathing.
This method is similar to the previous one except that the wall sheathing stops at the truss/top plate intersection. Separate sheathing is added between each truss, and edge nailed to blocking. Note that this blocking could be simple 2x blocks, a pre-fabricated wall section, or truss piece. A hurricane clip is required.