I want to use a 2x4 wall as my load bearing wall (parallel to the ridge line) supporting trusses. Because I'm using cantilevered truss s to cover front and back porches I have unusually long truss s (56') and am building where the code requires design for 75#/sq ft snow load , I'm investigating loading and stress. The load bearing wall is the inner of a double stud wall and is sheathed on it's outer face with 1/2" plywood sealed as my primary air barrier. If I frame the wall 16" OC it can easily support the snow load + dead loads. I'd like to use truss s 24" OC but the concentrated load at the bearing points, under maximum snow load+dead load results in excessive cross grain stress if the bearing area is only 3 1/2" x 1 1/2". Can I use a 2x6 top plate on a 2x4 wall to solve the problem? The 2x6 top plate will work because I'll be sheathing the bottom of the trusses and adding furring to form a ceiling "service cavity". I would center the top plate over the 4" (sheathed) wall below so there would be 3/4" overhang on both edges and glue it in place with construction adhesive for air sealing and added strength. If it will work, the 2x6 top plate is a lot more economical than resorting to 16" OC truss s which also solves the problem.
Posted Thu, 03/07/2013 - 14:06
Edited Thu, 03/07/2013 - 14:34
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