GYPSUM HAS BECOME A PREFERRED FLOOR UNDERLAYMENT IN PART BECAUSE IT DOES DOUBLE-DUTY, BOTH PROVIDING A NON-COMBUSTIBLE LAYER TO SLOW FIRE-SPREAD FROM FLOOR TO FLOOR AND DAMPING NOISE TRANSMISSION
Waiting for the other shoe to drop has been a common human experience since the invention of the two-story house. The disruptive thump heard in the room below is called impact noise, and over the centuries, floor-to-floor transmission of impact noise has proven difficult to tame. In applications such as multi-family housing, it is a significant issue. Numerous solutions have been developed to control both impact sounds (such as footfalls), as well as airborne sounds (such as speech or music). These solutions are complete floor/ceiling assemblies that have been tested and rated for noise isolation. They are standards, registered with UL Laboratories, and must be constructed exactly as the assembly was tested.
The floor/ceiling assembly also plays an important role in fire prevention. Gypsum has become a preferred floor underlayment in part because it does double-duty, both providing a non-combustible layer to slow fire-spread from floor to floor and damping noise transmission. Gypsum has proven an effective noise reducer, especially when poured on top of an acoustic mat that further decouples the floor from the subfloor, and numerous registered floor/ceiling assemblies using gypsum over acoustic mat are available.