How fire resistant is drywall?

This blog post will answer the question, “How fire resistant is drywall” and cover topics like fire-resistant properties of drywall and frequently asked questions related to the topic.

How fire resistant is drywall?

Drywall is a fire-resistant material. A 1/2-inch thick sheet of drywall can withstand a fire for 30 minutes, but the additional 1/8-inch found in Type X or C drywall, as well as its other qualities, will increase your margin of safety to 60 min.

What Is Type X Drywall That Is Fire-Rated?

The conventional word for fireproof drywall is Type X drywall, and the industry designation for it is Type X drywall. The thickness of this drywall, including all layers, is 5/8-inch.

To aid in the slowing of the fire, glass fibers are put on the board. It also takes longer for a fire to deteriorate since it is denser than regular gypsum and paper drywall.

The majority of Type X drywall has a one-hour fire-resistance rating. The 1/2-inch drywall used throughout the remainder of the house has a 30-minute fire rating.

Type X drywall also absorbs sound significantly better and is slightly stronger than standard 3/8-inch or 1/2-inch drywall.

Drywall Type X vs. Type C

Type X and Type C drywall are both classified as fire-resistant. Both are rated for a 60-minute wall system. The gypsum core of Type C drywall includes additional additives, making it marginally more fire-resistant than Type X drywall.

Why Fireproof Drywall Is Fire-Rated?

Type X or C drywall isn’t completely fire-resistant. Simply said, it’s drywall that can withstand flames better than conventional drywall.

Furthermore, just because an area is coated with Type X or C drywall does not mean that it is fire-safe, since fire may still enter via vents, doors, gaps, fractures, and unblocked stud wall assemblies.

If a standard 1/2-inch thick sheet of drywall can withstand a fire for 30 minutes, the additional 1/8-inch thickness found in Type X or C drywall, together with its other features, will increase your margin of safety to 60 minutes. As a result, fire-rated drywall is sometimes known as one-hour fire wallboard.

Where Should Type X or C Drywall Be Installed?

Building rules often require fire-rated drywall to be put in a handful of these spots in homes:

  • Located between the furnace and utility rooms
  • Places where you may use a wood stove
  • Garages, particularly the garage walls that divide that section from the rest of the home
  • Garage ceilings with residential spaces above them

Should You Use Type X or C Drywall Throughout Your Home?

No, fire-rated drywall isn’t meant to be used in every room of the house.

Ordinary drywall panels are around 20% more costly than fire-rated drywall panels. While this may not seem like much on a small scale, when multiplied over a complete home’s worth of drywall, it can add up quickly.

More significantly, the fire will find a variety of other routes to escape than drywall. For example, if Type X or C drywall was used in a bathroom, nursery, bedroom, or home office, the fire would easily proceed through oxygen-rich open doors and hollow-core doors before trying to burn through the drywall.

If you want fire-rated drywall built throughout your home, you’ll have to ask your contractor for it since it’s not standard practice.

Is it Possible to Burn Drywall?

Drywall can not be burned easily. Drywall is a common material used to line walls, construct inner walls, and create firebreaks in contemporary structures. Except for the paper coating on individual drywall sheets, it has a great flame resistance and is hence difficult to burn.

The base of a drywall sheet is effectively inflammable in the absence of a very high temperature, making it a great material for constructing firebreak barriers in the home and office. Drywall cannot be burned easily due to the following factors:

  • Composition
  • Toxicity
  • Resistance to fire
  • Gypsum

I will now elaborate on the guidance given above.

Composition

Drywall is tough to burn due to its composition. Drywall is made from gypsum and water that is squeezed between paper sheets. While the paper is combustible, burning it will evaporate the water, burning gypsum requires a very high temperature. As a consequence, drywall cannot be completely burned outside of industrial furnaces.

Toxicity

The gypsum in drywall is difficult to burn, but when the water content evaporates during the firing process, it will dry and flake. When inhaled, the particles that are emitted might cause health complications. As a consequence, burning drywall is not suggested for safety reasons.

Resistance to fire

Due to the presence of moisture in the gypsum, which evaporates and actively decreases the temperature of the surrounding material, drywall is extremely fire resistant. While the paper coating may easily burn, the drywall’s gypsum core will stay substantially intact. Drywall is a common option for firebreaks in contemporary structures due to its fire resistance.

Gypsum

Gypsum is a mineral that looks like clay and other plasters. As a consequence, it has a high melting point and is difficult to ignite outside of industrial furnaces and other heat sources. As a result of the high gypsum component in drywall, it has a strong fire resistance and cannot be entirely burnt for most applications.

Is Drywall Fire-Resistant by Nature?

Even though no wallboard is completely fireproof, the mineral in drywall can’t help but resist fire. The crystalline matrix of calcium sulfate dihydrate – gypsum – binds water molecules. It stays there until it’s heated to above 176 degrees F. Water makes up around 20% of the weight of gypsum and about 50% of the volume. Gypsum starts to release its water when it warms up, which prevents igniting or cracking until the water has steamed away.

When making wallboards out of natural or synthetic gypsum, it’s first ground to a fine powder, then warmed to release the water, resulting in plaster of Paris. The producer then adds more ingredients and just enough fresh water to make a paste that can be rolled out between two thick pieces of paper.

Regular drywall swells as water migrates out of the gypsum matrix under the heat of a conflagration, then splits and crumbles in approximately 20 minutes. Manufacturers created fire-rated Type X wallboards to extend the duration between failures.

What is Type X Drywall, and how does it differ from other types of drywall?

Glass fiber is added to the gypsum slurry for Type X drywall, which is then rolled to a minimum thickness of 5/8 inch. For up to an hour, the fibers function to prevent board cracking and disintegration. In the event of a fire, that additional time might be the difference between life and death. Type X or better is required between connecting garages and residential areas, as well as surrounding furnace and boiler rooms, according to many municipal construction rules. The drywall industry has now surpassed the code minimums by offering Type C wallboards that outperform Type X.

What is Type C Drywall, and how does it work?

Type C drywall begins with a glass fiber mix and progresses by increasing the quantity of glass and integrating a vermiculite-like mineral. This vermiculite additive has a unique feature. It expands at nearly the same rate as gypsum when heated to high temperatures. As a result, when the fire pushes the water out of the gypsum, causing it to compress, the vermiculite expands to keep the board in place.

Type C drywall was challenged against a conventional 5/8-inch drywall board and a Type X board in a controlled experiment when it was initially created by USG and tested in their laboratory at temperatures of 1850 degrees. They weighed the boards so that they could identify when each one failed. After 12 minutes, the standard board failed. The Type X board lasted a whopping 57 minutes, while the Type C board lasted a whopping 122 minutes before the experiment was called off. After two hours, the Type C board had lost none of its basic integrity, according to inspection. Independent testing later confirmed the additional glass fibers and vermiculite-based additive in Type C drywall’s enhanced fire resistance.

Will Fire-Resistant Gypsum Provide Better Protection for My Family?

While increased fire resistance is beneficial in any architectural application, the answer to the issue of whether fire-rated gypsum boards will operate as expected is complicated. No one can guarantee that fire-rated drywall, whether Type X or Type C, would fight back flames long enough to escape or obtain emergency help since laboratory testing and real-life fires are prone to so many factors. Open doors and stairwells, structural or architectural breaches that allow the fire to spread, an abundance of flammable items, and a variety of other factors all play a role.

It seems logical to assume that using fire-rated gypsum increases your chances of being protected in the event of the unimaginable. Codes, cost, and comfort level will ultimately take you to the best selection for your job.

What is drywall’s burning point?

At roughly 480 degrees, the paper on the drywall sheets will ignite. Furthermore, most drywall manufacturers state that drywall may be destroyed at 176 degrees Fahrenheit. The gypsum, on the other hand, does not burn.

Water makes up around 20% of the weight of gypsum. It avoids igniting by discharging its water content when exposed to fire. The gypsum drywall will begin to fracture or disintegrate after all of the moisture has drained.

Furthermore, depending on the kind of drywall you have, it might be even more fire-resistant. Some drywall kinds, such as type X or type C, have additives that raise the fire rating and delay the drywall from burning.

Frequently Asked Questions(FAQs), “How fire resistant is drywall?”

Is drywall good for fireproofing?

Drywall is moderately fire-resistant, however adding glass fibers to the mix may improve the resistance. Drywall is a fire-resistant material. It’s made of gypsum sandwiched between two thick pieces of paper. Gypsum is a soft mineral that is not flammable on its own.

Does drywall burn easily?

Drywall is tough to burn due to its composition. Drywall is made from gypsum and water that is squeezed between paper sheets. While the paper is combustible, burning it will evaporate the water, burning gypsum requires a very high temperature. 

What happens to drywall in a fire?

The wall will dehydrate if the temperature swings between 150° and 170° F. The gypsum board, on the other hand, will not be damaged by such dehydration. Sheetrock is classified as a type-X material because it may be utilized within a fire for up to 60 minutes without being damaged.

Is drywall combustible material?

Most normal wall and ceiling assemblies (including tile and stone finishes installed on traditional wood-framed walls) are considered flammable, which is crucial to know as a house inspector. Because of the paper front, drywall is also considered a flammable substance.

How hot is too hot for drywall?

Temp damage to gypsum is only permanent when temperatures are above 176°F, according to extensive research. Dehydration will occur at temperatures ranging from 140°F to 176°F, however, tests show that they will be recovered to ambient levels and that the drywall quality will not be compromised.

How long does it take to burn through drywall?

To aid in the slowing of the fire, glass fibers are put on the board. It also takes longer for a fire to deteriorate since it is denser than regular gypsum and paper drywall. The majority of Type X drywall have a one-hour fire-resistance rating. The 1/2-inch drywall used throughout the remainder of the house has a 30-minute fire rating.

References:

https://www.angi.com/articles/drywall-fire-resistant.htm#:~:text=Drywall%20is%20relatively%20fire%20resistant,is%20incorporated%20into%20its%20structure.
https://www.thisoldhouse.com/walls/21173181/fire-rated-drywall
https://www.thespruce.com/fire-rated-or-type-x-drywall-1821479
https://www.certainteed.com/drywall/what-fire-rated-gypsum/

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