StopGap Acoustical Sealant is a highly elastic, water-based sealant used for reducing sound transmission at the perimeter of wall systems or around electrical box cutouts to achieve specified STC/MTC values. The surface dries to a tough film but the sealant remains flexible and stays pliable for up to 5 times longer than alternative brands. And unlike other products, Stop-Gap has no residual run-off. StopGap is paintable and nonstaining, and meets ASTM C-834 standards for flame retardancy.

StopGap comes in a large, 29 oz caulking tube and therefore requires a larger than normal-sized caulking gun, which can be purchased at any local hardware store. Coverage per 29 oz. cartridge is approximately 89ft. with a 3/8 inch bead applied.
Auralex StopGap will achieve a Sound Transmission Class (STC) of 53 when applying it in accordance with ASTM C-919 “Standard Practice for use of Sealants in Acoustical Applications”. To achieve the 53 STC, StopGap should be applied as two beads of sealant at the top, bottom and all perimeter edges. Coverage per 28 oz. cartridge is approximately ~40 linear ft. with a 3/8 inch bead applied.