Is All Drywall Fire-Resistant? Here’s What to Know

Nick P. Cellucci
Written by Nick P. Cellucci
Updated May 5, 2022
open space grey kitchen
Photo: Roger Richter / Westend61 / Adobe Stock

Highlights

  • All drywall is manufactured using fire-resistant materials.

  • Different types of drywall resist burning for different periods.

  • Type C fire-rated drywall can resist burning for up to four hours.

  • Fire-resistant drywall costs 50% more than regular drywall.

  • Proper installation can increase drywall’s fire-resistance.

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If you’re building a home, considering house renovations, or just wondering if you’re properly protected in a worst-case scenario, you may be wondering if drywall is flammable. In short, all drywall is technically fire-resistant. However, not all drywall is created equal. Learn what prevents drywall from burning and how different types perform against fire.

Are Ordinary Drywall Panels Flammable?

All drywall is fire-resistant to some degree. Also called gypsum board, ordinary drywall panels are made of a layer of soft, non-flammable mineral called gypsum pressed between two thick sheets of paper. There is also water incorporated into the structure of the material, which effectively blocks the transfer of heat through the drywall.

When exposed to fire, drywall will not immediately ignite. The heat from the fire will begin to slowly vaporize the water within, simultaneously charring the drywall and causing it to lose about half its strength and stiffness. When the water vapor has dissipated completely, the gypsum will begin to heat and the drywall may begin to burn.

What Is Fire-Rated Drywall?

Temperature does not affect the fire resistance of drywall. Instead, different types of drywall can resist burning for certain periods of time depending on their ability to maintain structural integrity. No drywall can stop the spread of fire completely, but knowing the differences between regular and fire-rated drywall can help you know which is best for your project.

Regular Drywall

The most commonly used type of drywall in home construction is regular drywall made of gypsum plaster. This variety serves as a base for interior paint application and comes in various thicknesses including five-eighths-inch, half-inch, three-eighths-inch, and quarter-inch panels.

Half-inch panels, also called lightweight drywall, are the most common because they are easier to transport and handle. These are able to resist burning for up to one hour.

Type X Drywall

Type X is one of two types of fire-rated drywall specifically manufactured with special additives to provide superior mold, mildew, and fire protection. Type X drywall is usually made from thin sheets five-eighths of an inch thick that resist burning for up to two hours when applied in a single layer to both sides of standard wood framing in a house.

Type C Drywall

Type C drywall is also fire-rated and provides superior fire resistance compared to Type X. Depending on the project, Type C will resist burning for up to four hours. It also features a smooth surface that is very easy to paint.

Do You Need Fire-Resistant Drywall?

a stack of fire resistant plasterboard
Photo: ArieStudio / Adobe Stock

Fire-resistant drywall offers several benefits over regular drywall. Properly installed, it is more effective at containing a fire and slowing its spread, as well as protecting structural supports long enough for occupants to safely flee a burning building. However, it also comes at a higher price point than regular drywall—up to 50% more, according to HomeAdvisor.

For that reason, most drywall contractors will try to increase the cost-effectiveness of any construction project by reserving fire-resistant drywall for rooms with specific fire hazards and materials where fires are most likely to originate. This typically includes high-risk areas or rooms with equipment that may cause a fire, such as garages, basements, and kitchens.

Proper Drywall Installation for Maximum Fire Resistance

The way drywall is installed can also impact its fire resistance. Once drywall is attached to the wood or steel studs of a home, there are small gaps between sheets that air, smoke, and fire could pass through. Drywall contractors will apply tape and joint compound to close these gaps. Drywall can also be applied in multiple layers to increase fire resistance.

Your local drywall contractors should know your local and state standards and fire codes regarding the application and finishing of drywall, and some homes may require certain types of drywall depending on those building codes. For example, the building codes for a furnace room will be different from a bedroom.

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