Fire blocking or firestopping is a system of supplemental components in a wood-framed wall or ceiling, which prevents the rapid propagation of fire within a combustible framing cavity to other areas.
Description and function
In wood framed construction, fire blocking usually takes the form of short lengths of the same dimensional lumber used in the wall or floor/ceiling framing, installed perpendicular to the primary structural framing, completely obstructing the wall cavity. The
International Residential Code (IRC) and
International Building Code
The International Code Council (ICC), also known as the Code Council, is an American nonprofit standards organization sponsored by the building trades, which was founded in 1994 through the merger of three regional model code organizations in th ...
(IBC) both require fire blocking in combustible construction at transitions between horizontal and vertical framing, and in vertical cavities at intervals at no more than spacing between blocking, at the top and bottom of stair framing, and within exterior cornices.
Other materials used for fireblocking may include noncombustible materials such as gypsum board, cement board, or mineral fiber insulation blankets
Fire blocking is most critical in
balloon framing
Framing, in construction, is the fitting together of pieces to give a structure, particularly a building, support and shape. Framing materials are usually wood, engineered wood, or structural steel. The alternative to framed construction is ...
, where a cavity may traverse multiple floors. More modern methods of platform-framing provide inherent fireblocking in most cases, since the cavity is interrupted at every floor level by top and bottom sill plates. Fire blocking may also serve as
bridging between framing elements, stiffening them against lateral buckling.
Fire blocking or firestopping terminology was used interchangeably in code language from its first mention in the 1905 National Building Code (NBC), and requirements were expanded in the 1927
Uniform Building Code (UBC). Building code terminology settled on different definitions of the terms by 2000.
References
{{reflist
See also
*
Firestop
A firestop or fire-stopping is a form of passive fire protection that is used to seal around openings and between joints in a fire-resistance-rated wall or floor assembly. Firestops are designed to maintain the fire-resistance rating of a wall ...
, specifically-formulated materials that prevent fire migration at joints between materials and at penetrations in building elements
Firestops