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Re: doubled plywood sheathing on one side of shear wall to increase c apacity?

[Subject Prev][Subject Next][Thread Prev][Thread Next] This is probably best answered by APA from their test data, however, I am under the impression that the shear capacity of the all is greatly influenced or dependent upon the size and embedment of the nails used. This is why there is a 15% reduction required where sinkers are used in lieu of common nails.
So, in short, the answer is that the nailing governs and the engineer can not assume twice the value for double sheathing on one side of the wall.
The code does provide for reduced values of plywood sheathing when applied over gypsum - which I assume is to compensate for bending in the nails due to the softer gypsum material.
Any rebuttals?


At 09:16 AM 9/18/2001, you wrote:
1997 UBC 2319.3 says "Where wood structural panel is applied to both faces
of a shear wall ..., allowable shear for the wall may be taken as twice  the
tabulated shear for one side, except that where the shear capacities are not
equal, the allowable shear shall be either the shear for the side with the
higher capacity or twice the shear of the side with the lower capacity,
whichever is greater."

I have seen several designers try to increase the capacity of a wall by
applying two layers of sheathing on one side of the wall.

Is doubling the sheathing on one side of a wood structural panel shearwall
an acceptable way of increasing the capacity? Has there ever been any
testing for this assembly? How come the code does not mention it?


Scott M Haan P.E.
Plan Review Engineer
Building Safety Division
Development Services Department
Municipality of Anchorage

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