scope:

Introduction

Dividing buildings into distinct fire-protected areas is typically accomplished by providing fireresistance rated separations between those areas. This type of separation is easily achieved by the use of gypsum board applied to either wood or steel framing members. These fire-rated separations are usually provided as total assemblies, consisting of the structural member, the gypsum board and structural flooring material (if a floor/ceiling assembly). Listings of many fire-rated assemblies or Designs are found in the GA-600, UL Fire Resistance Directory, etc.

However, often no fire-rated assembly exists to match a particular configuration to be built. This is often the case for retrofit work, but may also occur in new construction. In this case all of the fire resistance may be provided by a gypsum board "membrane"; typically several layers of fire-rated (type X) gypsum board.