It’s a question that has been asked by homeowners for years – is drywall flammable? The answer, it turns out, is a little complicated.
Drywall does not combust by itself, but it does produce toxic gases when exposed to high temperatures. That is why the smoke inhalation resulting from an accidental fire in drywall is very dangerous. The material itself can burn but it will not melt or drip.
Different types of drywall
There are several different types of drywall, so it is important to know the differences between them so you know which type is best for your project.
You will see them made of various materials such as Calcium silicate (gypsum), calcium sulfate dihydrate, magnesium oxide, and aluminum trihydrate.
Regular drywall is the most popular type of drywall used in homes and commercial applications. It is made of gypsum plaster pressed between two thick sheets of paper and serves as a base for any interior paint applied.
They come in various thicknesses such as 5/8-in., 1/2-in., 3/8-in., and 1/4-in.
The most commonly used drywall thickness is 1/2-in. also called lightweight drywall. In addition, you can also find 3/8-in. and 1/4-in. panels which are only available in shorter lengths, so you will need to order more of them if you need to cover a large surface area.
Why Use Lightweight 1/2 in. Drywall?
One of the main reasons homeowners choose lightweight drywall over the thicker versions is because it is easier to transport and handle. It also has improved durability, which means less harm to the edges when handling and more resistance to sagging.
Mold-resistant drywall has all the same characteristics as regular but it also provides extra protection against moisture and mold. It is the perfect choice for homeowners who live in humid environments.
Drywall comes with a thin plastic coating on one side to prevent it from absorbing excess moisture and reduce the risk of mold formation. Special added additives such as potassium permanganate will help it to become mildew resistant.
TIP: This drywall is great for ceilings, which can get a lot of moisture.
Mold-Resistant Drywall vs. GreenBoard
The GreenBoard is a prior form of water-resistant drywall which was developed in 1960 and later on mostly replaced with materials that combine moisture resistance and mold resistance.
Greenboard is not mold resistant. The waxy substance on greenboard paper sheets helps to keep water away, but extremely wet conditions can still cause the paper to collapse and peel away from the gypsum core. Mold-resistant drywall has a thin plastic coating on one side, which helps prevent it from absorbing excess moisture and reduce the risk of mold growth.
Fire resistant drywall offers superior protection against fire damage as well as mold and mildew. In addition to the thin plastic coating, they also contain moisture-resistant additives such as potassium permanganate and aluminum trihydrate which make it highly fire-resistant.
NOTE: Fireproof drywall provides fire resistance for up to 4 hours. You will see them mainly used in garages, basements and around equipment that might cause a fire.
Type X drywall
Type X drywall is a type of fire-resistant drywall that is made from thin usually 5/8” thick sheets and similar characteristics to plaster. It provides fire resistance for up to 2h depending on other factors in your home.
The main benefit of type X drywall is special additives that allow you to use it in fire-rated projects compared to the regular type, which you can not.
Type C drywall
Type C drywall offers superior fire-resistance protection up to 4 hours, depending on the project. Besides the fire, it is resistant to water, mold, and mildew. Its smooth surface makes it great to paint.
Soundproof drywall panels have an interior layer made out of gypsum, viscoelastic, and ceramics which makes them significantly more robust and less able to transmit sound waves (STC) compared to regular types.
This makes them perfect for usage in noise-sensitive settings such as home theaters, recording studios, and other high-traffic spaces.
VOC-absorbing drywall is a great choice for those who are more environmentally conscious as it reduces harmful VOCs (volatile organi cc compounds) by up to 99%.
VOCs are organic chemicals that are emitted from many household items such as paint, carpeting, furniture, and cleaning supplies. This Drywall absorbs these chemicals and other volatile organic compounds and retains them within the drywall, making them harmless.
Plasterboard, often known as the blue board, is a foundation for plaster applications that is comparable to lath in lath and plaster walls. Thin coats or several layers of plaster must be applied to the whole surface of the plastered board.
This is a common variety of drywall that is used in older homes to achieve a look similar to stone or brick.
Is drywall flammable?
While drywall itself is not flammable, the gypsum core that it’s made of can be combustible under the right circumstances. When exposed to a fire, drywall will char and lose its strength. At the same time, its gas and water vapor will be driven out. Gas contains hazardous chemicals which are very harmful to your health if inhaled.
All types of drywall will resist fire for a certain period of time, but none can stop it completely. Regular drywall material won’t burn during the first hour and Type C can last up to 4 hours.
NOTE: Drywall loses about half of its strength and stiffness when it is heated to 100 °C (212 °F) and up to 70% relative humidity.
What temperature does drywall catch fire?
Fire resistance of drywall does not depend on temperature, but rather on time. The more flammable the material is, the less time it will take for a fire to spread and reach the panels.
Drywall will start catching fire when exposed to a temperature of about 120 degrees Celsius (about 250 degrees Fahrenheit).
At this point, smoke is produced that can irritate the eyes and nose. The plaster on the back of the drywall may produce carbon monoxide when it burns. This dangerous gas will offer no warning because your senses are quickly overcome by its odorless presence.
Do I need fire-resistant drywall?
Fire-resistant drywall is more effective than normal drywall at containing the fire in its source region. When properly installed, it will prevent flames and heat from spreading across rooms, floors, and buildings, as well as protect structural supports long enough for occupants to flee and buildings to be saved.
Because of its higher price point, fire-resistant drywall is normally placed only in rooms that are at the greatest risk for fire because of their contents, activities, or location.
NOTE: Some homes may require certain types of drywall depending on their local building codes.
How do you know if drywall is fire-rated?
There are many ways to find out if drywall is fire-rated.
- One of the most common ways is to read the label on the packaging, which will usually state whether or not it has a fire-resistant rating.
- You can contact the manufacturer to inquire about its fire-resistant properties and protection levels.
- If your interior wall is already finished and painted, try contacting the building department in your area as well as asking an architect or contractor who made it.
Is drywall more fire-resistant than wood?
Wood has an ignition point of 464 degrees Celsius (867 Fahrenheit), while drywall can ignite at 120 degrees Celsius (248 Fahrenheit). However, the insulation values are key when it comes to fire. Wood offers a protection level of 30 minutes while drywall comes with a fire-resistance period between 1 and 4 hours.
Are sheetrock and drywall the same thing?
Drywall and sheetrock are the same. They both refer to gypsum panel products used for building interiors.
Is fire-resistant drywall also moisture resistant?
Yes, most fire-resistant drywalls are made to resist moisture. This allows them to function as a vapor retarder and keep condensation from forming on the inside of a wall.
Is 'Green' Drywall environmentally friendly?
Green drywall is certified as reclaimed and recyclable and was developed using waste products.
Is drywall dust flammable?
Drywall powder is not flammable. It will only catch on fire when its temperature reaches more than 450 degrees Celsius (842 Fahrenheit), but this takes a long time in comparison to other materials.