What is the effect of adding additional layers of gypsum wallboard on STC ratings?
STC ratings are not derived by adding gypsum wallboard piece by piece, but by testing the wall system as a whole in a laboratory setting. How much noise attenuation is gained from adding additional layers of gypsum board will depend on how the wall is constructed. Conventional studs easily conduct noise vibrations from one side of the wall to the other. Quietzone™ studs isolate and break noise vibrations throughout the wall thus significantly reducing noise transmission over conventional construction practises. For additional guidance on the effects of gypsum on wall assembly STC ratings, please see the Gypsum Association Website.
