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Design of Wood Top Plates

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What is the common practice for the design of top plates for a load 
bearing wood stud wall (non-hurricane or seismic area).  The NDS has a 
Flat Use factor for 2 x 6's used on their weak axis.  The problem is the 
factor only applies to the Allowable Bending stresses (Fb) and not to the 
Allowable Shaer Stresses (Fv).  The problem is I have trusses with a 2.8k 
reaction on a 2 x 6 @ 16 " o.c. stud wall.  A double top plate will not 
calc. out (2 x 6 SPF Stud Grade Fv=70 psi per NDS 1991)  Based on the 
calcs, I would need approximately 5 plates (or if No 2 Southern Yellow 
Pine was used 4 plates).  The architect would not accept this (over 
engineered)  and the chances of having the workmen locating a stud 
directly under the truss is not good.  Are there any factors I am 
missing?  I understand that the shear check for wood is for a horizontal 
shear and wood think a flat member would resist it better.  Anyone have 
any suggestions?