Local fire codes regulate the installation of fire rated drywall and the application of fire-resistant construction techniques. Although the rules vary from community to community, it's standard to install a fire-resistant wall between an attached garage and a residence, and between individual stores in a commercial setting. Drywall panels, made from gypsum, are naturally resistant to fire, but you can achieve more fire protection by installing fire-rated drywall, especially made to slow down a fire's progression from one room to the next.
Type X Drywall
Type X drywall contains added fiberglass to retard the spread of fire. Type X drywall is 5/8-inch thick and available in 4-foot widths and lengths that vary from 8-foot to 12-foot. To meet fire codes, you will typically install Type X drywall on both sides of the wall studs. Staggering seam joints may also be a requirement.
Type C Drywall
For increased fire resistance, you can install Type C drywall, which contains more fiberglass than Type X, in addition to other fire-resistant materials. Type C is available in 1/2-inch thickness as well as 5/8-inch thickness, and it further reduces heat transfer through the wall.
You may use regular drywall, if permitted by local code, to construct a firewall. Due to an approximate 21 percent chemical water content, regular drywall begins to steam when it encounters fire. This steaming slows heat transfer. By installing a double layer of regular drywall, you will obtain a higher fire-resistant rating in the wall.
Constructing a Firewall
There's more to constructing a firewall than just hanging fire-rated drywall or a double layer of regular drywall. Local codes may require the application of fire-rated drywall compound and drywall tape over the seams between the panels.
To be effective, a firewall prevents the flow of air from one room to the next. This involves the installation of a fire-rated door that seals tightly when shut and special fire-rated wall outlets and switches.
Installation of a fire-rated door is essential to meet fire codes. The door must remain shut to maintain fire resistance.
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