My client would like to add a heavier tile roof to his 2-story, wood frame, type V house in the hills of Los Angeles. The second story addition 4-years ago included new plywood shear walls per the 1997 UBC and all evidently permitted. In reviewing the calcs of this addition, I note that the engineer took the Code shear wall values and multiplied them by .75. I cannot find the responsible engineer to query, and I cannot find a Code reference as to why the 25% reduction. These are seismic loads not permanent loads, and the Struc I panels are spec'd with common nails (15/32 Struc I w/ 8d Common @ 3" and 4"). What am I missing?
Charles Laines, S.E.
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