Firewall (construction)

A firewall is a fire-resistant barrier used to prevent the spread of fire for a prescribed period of time. Firewalls are built between or through buildings, structures, electrical substation transformers, or within an aircraft or vehicle.

Firewalls can be used to subdivide a building into separate fire areas and are constructed in accordance with the locally applicable building codes. Firewalls are a portion of a building's passive fire protection systems.

Firewalls can be used to separate-high value transformers at an electrical substation in the event of a mineral oil tank rupture and ignition. The firewall serves as a fire containment wall between one oil-filled transformer and other neighboring transformers, building structures, and site equipment.

There are three main classifications of fire rated walls: fire walls, fire barriers, and fire partitions. To the layperson, the common use of language typically includes all three when referring to a firewall unless distinguishing between them becomes necessary. In addition specialty fire-rated walls such as a High Challenge Fire Wall would require further distinctions.

Fire barrier walls are typically continuous from an exterior wall to an exterior wall, or from a floor below to a floor or roof above, or from one fire barrier wall to another fire barrier wall, having a fire resistance rating equal to or greater than the required rating for the application. Fire barriers are continuous through concealed spaces (e.g., above a ceiling) to the floor deck or roof deck above the barrier. Fire partitions are not required to extend through concealed spaces if the construction assembly forming the bottom of the concealed space, such as the ceiling, has a fire resistance rating at least equal to or greater than the fire partition.

Portions of structures that are subdivided by fire walls are permitted to be considered separate buildings, in that fire walls have sufficient structural stability to maintain the integrity of the wall in the event of the collapse of the building construction on either side of the wall.

Firewalls are used in varied applications that require specific design and performance specifications. Knowing the potential conditions that may exist during a fire are critical to selecting and installing an effective firewall. For example, a firewall designed to meet National Fire Protection Agency, (NFPA), 221-09 section A.5.7 which indicates an average temperature of 800 °F, is not designed to withstand higher temperatures such as would be present in higher challenge fires, and as a result would fail to function for the expected duration of the listed wall rating.

...
Wikipedia