Finish TradesQuestion 251 of 700
Which combination of assembly changes will BEST raise the Sound Transmission Class (STC) of an interior partition?
a.Using thinner drywall on both sides
b.Leaving the stud cavity empty and rigidly attaching both faces
c.Sealing all cracks with rigid mortar and adding no insulation
d.Adding cavity insulation, a second layer of gypsum, and decoupling one face with resilient channel
Explanation
Sound isolation improves with added mass (second gypsum layer), absorption (cavity insulation), and decoupling (resilient channel) to break the vibration path. Thinner board, an empty rigidly attached cavity, or rigid connections lower STC by transmitting sound more directly.
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