A. Frank Woeste, P.E., responds: I am not aware of any performance issues regarding 1/2-inch drywall installed on trusses at 16-inch versus 24-inch centers. If interior moisture were improperly managed — for example, if a clothes dryer were vented into a finished garage area instead of to the outside, a 16-inch on-center truss spacing would be more forgiving of the bad practice.
But in general, it doesn't matter if the truss spacing is at 12, 16, or 24 inches. What dictates the truss design is the roof design snow load — typically 20 or 30 psf in most of the U.S. Once the builder or architect specifies the loads (for example, 20-10-0-10, for top chord live, top chord dead, bottom chord live, and bottom chord dead loads)...
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