Does Drywall Burn? Is it Flammable?
Drywall is a popular choice for walls and ceiling applications is that it is very easy to install and repair. But that’s not all; drywall provides great fire-resistance qualities as well as insulation, soundproofing, and insulation. But, does drywall burn? Is it completely fireproof?
Drywall is fire-resistant and won’t burn unless the flame temperature exceeds 176°F. It is non-flammable because it is made of gypsum and water. Type X drywall is 5/8-inch thick and contains special additives like fiberglass to increase it’s fire resistance making it the most fireproof drywall.
Here are the fire ratings for different types of drywall:
|Type of Drywall||Fire rating|
|Type X ⅝-inch||1 hour|
I’ve discussed the differences between standard and fire-rated drywall, and how to safely dispose of unused drywall panels even when you cannot burn the Sheetrock waste.
Does drywall catch fire and burn?
Drywall is popularly used for fire-proofing of building walls as it boasts exceptional flame resistance. To understand why drywall is such a good fire barrier, you need to understand its construction.
Drywall is basically composed of two sheets of paper enclosing gypsum – a soft, inflammable mineral. Plaster minerals like gypsum have extremely high melting points, making them hard to burn.
Additionally, when making Sheetrock, the gypsum is usually mixed with water and then machine-pressed between two sheets of paper to make drywall sheets. This water content improves the fire-resistance capabilities of drywall even further as it evaporates during fires, cooling down temperatures in the immediate environment.
Different types of drywall have different fire codes. Therefore, some panels may be rated at least 30 minutes to about 2 hours depending on the thickness. While the thickness of the drywall can improve its fire rating, it is not the only thing that makes drywall panels more fireproof.
How hot does drywall have to be to burn?
The paper covering the drywall panels will readily burn during a fire outbreak while the gypsum section of the panels will start to burn when fire temperatures exceed 176°F. At such high heat, the gypsum will suffer structural damage and will weaken and start to disintegrate.
Standard drywall sheets can withstand relatively high temperatures caused by fire. However, the best fireproof drywall is the fire-rated type
What is fire-rated drywall?
Fire-rated drywall is 5/8-inch thick drywall made using paperboard and gypsum like standard drywall, but glass fibers are added to it to improve its fire resistance to at least 1 hour. Fire-rated drywall is also called type X drywall and is better at retarding fire, soundproofing, and insulation.
Pro tip: The core of fire-resistant drywall is dense and fiber-reinforced to help contain fire. You’ll find such drywall in ½, ⅝, and ¾ thicknesses. It is a requirement to install Type X (fire-resistant drywall) in garages, utility, and furnace rooms.
While standard drywalls boast excellent fire resistance, they can only withstand fires for about 30 minutes or so. After that, they start to shrink and lose their structure, leading to gaps through which fire can pass through and cause damage to the wall substrate.
By contrast, fire-rated drywall features more fireproof materials in its construction, including fiberglass. These additives enhance the duration for which fire-rated Sheetrock can withstand fires and prevent the fire from spreading.
Despite being more expensive than regular drywall, fire-rated drywall is definitely worth it, especially in areas that are prone to fire outbreaks such as garages and kitchens.
Additionally, depending on where you live, most building codes usually require the use of fire-rated drywall in certain areas of the building. There are three common types of fire-rated drywall-namely type X drywall, type C drywall, and type X Shaftliner. Here’s a brief overview of each:
Type X Drywall
For drywall to be rated as type X for fire performance, it should be 5/8 inches thick, with a minimum fire rating of one hour. Type X drywall features fiberglass material incorporated into its gypsum core for added fireproofing capabilities.
Type C Drywall
This type of fire-rated sheetrock is usually available in ½-inch and 5/8-inch thickness options. It features even more fire-resistant additives within its gypsum core, alongside the fiberglass material, making it even more fire-resistant than type-X drywall.
One of these additives is vermiculite, which expands as temperatures rise during a fire, effectively replacing the moisture lost as a result of calcination. As a result, less shrinkage occurs during fire outbreaks. Type C fire-rated drywall is able to maintain its structural integrity much better during fires.
Type X Shaftliner
This type of drywall has the highest fire rating, which can be largely attributed to its thickness (1-inch thick).
Note that, despite the obvious fireproofing advantages offered by fire-rated drywall, it may not be a good idea to install it everywhere, as it’s significantly more expensive than standard drywall.
Pro tip: To cut down on costs, I recommend you only install fire-rated drywall in the most fire-prone areas including utility rooms, kitchens, furnace spaces, garages, and garage ceilings.
Does drywall act as a fire barrier?
While drywall boasts great fire-resistance capabilities it isn’t designed to be 100% fire-proof. Its main purpose is to slow down the spread of fire to other areas of structures, thus allowing occupants ample time to evacuate the premises.
The amount of time for which drywall will act as a fire barrier during fire outbreaks depends on its fire rating. For instance, regular drywall will prevent fire from spreading for at least 30 minutes, while fire-rated sheetrock will act as a fire barrier for one hour or more.
Can you burn drywall pieces?
At the end of your drywall installation project, you’ll most likely have drywall panel pieces still lying on site. You may be wondering whether you can safely dispose of them by setting them on fire. The simple answer is ‘no’.
Do not burn drywall pieces as a way of disposing of them. If you try burning the pieces of sheetrock, flaky particles that are dispersed into the air as the drywall dries up can trigger respiratory health issues if inhaled.
It is also very difficult to reach high temperatures (above 176°F) unless you have access to an industrial furnace. As such, it’s advisable to seek alternate, better ways to dispose of your unused drywall sheets. These include repurposing the drywall pieces by removing the paper backings, breaking down the gypsum into powder form, and spreading the powder into your garden. The gypsum will improve the workability of your garden soil.
You can also add the gypsum powder to your compost to improve its tilth. Gypsum powder can also be used to lower soil pH- much in the same manner as limestone- if you have very acidic soil.
However, take note that- compared to limestone- it takes a substantial amount of gypsum powder to lower the alkalinity of your soil pH.
Finally, you can save your panels for later use if any DIY repair is needed. For instance, you may need to fix minor issues related to wear down the line, such as small crumbled drywall areas due to water damage. Instead of having to spend on new drywall panels, you can use the leftover pieces that you’d saved up.
Drywall does not burn readily because it is composed of gypsum and water, making it non-flammable. 5/8-inch drywall is the highest fire-rated type and is thus the most fireproof. The two paperboard plates that sandwich the gypsum can still catch fire at 451°F but the gypsum will get damaged at 176°F.
MORE ABOUT DRYWALL