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1 hour exterior wall

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Hi Dave:


You can do it either way structurally.  Plywood over drywall has reduced shear values in the code.


You may want to consider adding the plywood first, then applying drywall (or plaster).  On the exterior face I use 1 inch thk. cement plaster, but you can use 5/8” thk. Type X Gypsum Sheathing.  This is black coated paper drywall intended for exterior applications.  Check out the Gypsum Association web site for U.L. listed fire ratings.  Use an approved assembly and call out the approval number on your drawings.



IDS Group, Inc.

Bob Freeman, AIA, EIT

(949) 387-8500