Firewalls and fire barriers are both designed to prevent a fire from spreading, but these often-confused structures are actually quite different. Ideally, firewalls and fire barriers are used together to make a structure as safe as possible. These are the key factors in understanding the use of firewalls and fire barriers in construction.
The Facts About Firewalls
Firewalls are strong walls built to resist fire for up to four hours, remaining erect even if other parts of the building collapse. These exterior walls are thicker than standard walls and stretch from the foundation up to the roof. Structures subdivided with a firewall between them are considered separate buildings.
Firewalls must be constructed with materials that meet the fire-resistance building standards set by the American Society for Testing and Materials (ASTM). Long, high firewalls may be supported with pilasters or buttresses. A standard firewall is made from concrete or masonry and does not have windows, doors, or other openings. Expansion joints allow the material to expand to withstand the fire’s heat.
Firewalls do more than just contain the blaze. They must also withstand force from other structures or items that collapse within the building, such as inventory or storage.
Exploring Fire Barriers
Unlike exterior firewalls, fire barriers are walls built within a structure. They can either extend from the floor to the roof or from one floor to the ceiling of the floor above. These subdividers can cover hidden spaces and are supported by floors, columns, roofs, and other interior structures. Fire barriers can resist fire for up to three hours as long as the supporting structures have the same level of fire resistance.
This design can allow occupants to safely evacuate the building while containing the fire to the smallest possible area. This can protect the building both from fire and smoke damage, as well as water damage from sprinklers. A one-way fire barrier withstands flames from one side only. Two can be placed together to block fire from both sides.