Case studies illustrating the importance of de-coupling the mass layers of demising walls in multi-family luxury condominiums and townhomes

摘要

Noise Isolation Class (NIC) tests, Field Measured Apparent Sound Transmission Class (ASTC)tests and acoustical measurements of impact noise from cabinet door and drawer impacts weremade of demising walls in a number of multi-family luxury townhomes and condominiums dueto complaints from residents about noise intrusion from adjacent living units. The demising wallconstructions included pre-cast concrete with gypsum board attached, concrete masonry units(CMU) with gypsum board attached and gypsum board on wood studs. The results of thesemeasurements demonstrate the need to de-couple the mass layers to maximize the acousticalperformance of the wall. A case study of one project will be presented showing the effects ofincremental changes made to a base wood stud wall with gypsum board on each side (ASTC 36)in which added mass (ASTC 44), added mass plus de-coupling (ASTC 62), and de-coupling withreduced additional mass (ASTC 58) were tested in an effort by the developer to strike a balancebetween acoustic performance and cost.