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Firewall Assemblies

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Passive fire protection is a method for preventing the spread of smoke and flames along with containing the fire at its source. It’s critical for commercial buildings, as it allows occupants the time needed to safely evacuate the building. Unlike fire extinguishers and sprinkler systems, these passive protection systems utilize fire-rated wall assemblies that have fire-resistant materials.

The Purpose of Fire-Rated Wall Assemblies

For optimal passive fire protection, different fire-resistant materials must be used together to slow the spread of toxic gases, smoke and blazes. A good example is the interior and exterior of commercial wall assemblies. Gypsum wallboard, light-gauge steel studs and fiberglass insulation are used together for total passive fire protection. These materials are used in a variety of layers and thicknesses to ramp up fire resistance. It’s a systematic and coordinated approach to maximize fire protection.

Fire WallTypes of Fire-Resistant Wall Assemblies

Wall assemblies vary, but the most common type include one-hour rated, two-hour rated and area separation firewalls. Both one-hour and two-hour rated assemblies can be applied vertically or horizontally. Gypsum board is fastened to steel studs with steel screws. For the most part, the difference between the two is the spacing. For extra fire resistance, 2 ½ inches of fiberglass batt insulation is added to the wall cavity.

Area Separation Firewalls

Firewalls are an important component of fire-resistant wall assemblies. These structures are often required in commercial buildings, townhomes and apartment complexes. The area separation firewall is engineered for collapse without the collapse of the whole wall. To accomplish this, aluminum breakaway clips are attached to the framing and wall. If one side of the separation firewall is exposed to a fire, the clips are designed to break away. The fire side of the wall collapses while the unexposed side continues to provide support for the separation wall.

Generally, separation firewall assemblies have two layers of 1” x “24” gypsum shaft liner panels inserted between the ceiling and floor runners. Proper installation of a firewall assembly includes following the manufacturer’s specifications and the system’s requirements. Keep in mind that an additional passive fire stop system is required in order to seal off gases and smoke from the joints.

Passive Fire Stop Systems

Fire Rated DrywallOften, toxic gases, flames and smoke penetrate through fire-rated wall assemblies at HVAC ductwork, electrical box, cable and switch perimeters, so sealing is necessary. Sealants like silicone and latex are often used. Contractors can choose these sealants in spray, caulking and leveling grades.  Backing material like polyethylene backer rods are often used for additional support. Intumescent materials are another good alternative. These fire stop products expand in volume when in contact to flames or heat exceeding high temperatures. With expansion, the gaps are closed, and the firewall retains its integrity. Intumescent materials come in various forms, including metallic collars and caulks.

Today, the integration of intumescent fire stop materials with steel framing is the latest innovation. Many commercial projects are now using steel tracks that have a metered dose of intumescent material. This is the ideal solution for controlling both hidden and exposed conditions that may be susceptible to fire. This new single-source construction of wall assemblies enables drywall contractors to complete joint protection while delivering up to three-hour fire-rated protection. These systems are easy to install and eliminate the need to return and do caulking.

Firewalls, fire-rated assemblies and passive fire stop systems are important elements in commercial buildings. Occupant safety is enhanced, and contractors can meet building code requirements. In combination with active fire protection methods, these passive fire protection methods are a well-balanced strategy to protect occupants and the building itself.


Firestop Product Guide Download

Photo credit: kruder396 / Foter / Creative Commons Attribution-ShareAlike 2.0 Generic (CC BY-SA 2.0)
mmatins / Foter / Creative Commons Attribution-NoDerivs 2.0 Generic (CC BY-ND 2.0)

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Wallboard Supply Company is a third generation, family run business that has been serving New England's building needs since 1970. Bob Filion started the company with a commitment to provide quality drywall and finishing products with unmatched customer service. The company has grown over the years, expanding its' product range, but never wavering from its' core values.