Knowing how hot drywall gets before catching on fire is useful information for any homeowner to have.
Often we have drywall around wood-burning stoves, fireplaces, or near ovens in the kitchen.
Just how hot can these panels of drywall get?
The answer depends on various factors, but we’ll break it down so you know how hot is too hot for your drywall.
Gypsum drywall burns at 481° degrees Fahrenheit (249° C). For safety, your drywall should not exceed 115° degrees Fahrenheit (46° C) over ambient temperature. This means if your room is 75° degrees Fahrenheit (24° C), the drywall should not exceed 190° degrees (88° C). Different drywall types have different heat ratings, so the precise temperature varies.
Drywall gets pretty hot before actually burning.
However, just because it doesn’t catch on fire doesn’t mean it’s meant to get so hot.
Read on to see how hot drywall can safely get and other information.
What Temperature Does Drywall Catch On Fire?
Most people are concerned with fire hazards when they ask how hot is too hot for drywall.
Drywall is a combination of gypsum board sandwiched between paper.
The paper catches on fire at temperatures around 481° degrees Fahrenheit (249° C).
Gypsum is a soft mineral and is not a combustible material.
However, other materials around the drywall, like dry wood, may have a lower combustion temperature.
Gypsum in drywall keeps it from being an extremely combustible material.
While it may not catch on fire, the high surface temp will still damage the gypsum and negatively impact the integrity of the drywall.
Studies show permanent damage to gypsum occurs when the actual temperature exceeds 176° degrees Fahrenheit (80° C).
Temperatures between 140-176° degrees Fahrenheit (60-80° C) cause dehydration within the gypsum board, but this is usually restored once ambient levels are restored.
Knowing what temperature damage and fire occur for drywall is part of being a responsible homeowner.
The precise temperature varies a bit on the type of drywall.
There are also different types of drywall with different fire-safety ratings.
Some are built to hold off the fire for a certain time.
This allows more time for people to evacuate a house fire before the walls are fully engulfed in flames.
Drywall also requires temperatures not to exceed a certain ambient temp as well.
How Hot Should The Drywall By My Wood Burning Stove Get?
Most people wonder how hot drywall gets before catching on fire when installing or using a wood-burning stove.
Wood stoves produce high temperatures, so it’s important to take expert advice about wood stoves to keep them safe.
This is great for heating your house on a cold winter’s day but is dangerous if the stove and hearth products are not properly installed.
There are many regulations for clearance distances and heat shields to keep you safe and reduce the hazard of wood stoves during the heating season.
Wood burners cause elevated temperatures for the ambient room temperature and surface temp.
Single Wall Vs. Double Wall Pipe
One way to keep the drywall from getting too hot is by using the correct flues.
There are single-walled pipes and double-wall pipes.
Single wall pipes are great for throwing off more heat but need more clearance for safe operation.
Single wall pipes need to be further away from combustible material like drywall as they throw off more radiant heat.
A double wall pipe or double-wall chimney has a lower flue temp and allows for closer installation to a protected combustible wall.
There are specific regulations around safely installing both a single wall pipe and double wall pipe for your wood-burning stove.
Depending on the stove model, make sure to adhere to these code regulations in the stove manual to keep your home safe.
Other Ways To Keep Wood Burner Safe
Even if the wall doesn’t catch on fire, the excessively high temperatures will cause degradation and slowly increase the flammability of the materials.
It will also damage wood trim edges.
Make sure you have adequate clearance to walls for peace of mind.
Using double-wall stove piping allows you to have them closer to combustible walls, which is a great option if you are limited on space.
Additional heat shields help to decrease the necessary clearance of walls.
They provide proper wall protection when using your stove and prohibit unnecessary damage to combustible and non-combustible materials.
Proper heat shield designs allow for adequate air space from the backer board to allow pipes to be closer to combustible surfaces while maintaining safety.
This supplies your wall with protection when using the stove, depending on the type of heat shield.
Here are some other tips for using a wood-burning stove safely:
- Using a hearth pad keeps sparks and hot coals from burning the hearth floor. Incorporating a proper hearth design will help to keep you and your nice hearth intact.
- Allow adequate ceiling clearance from the stove. Sloped ceilings may have hot spots. Certain materials will make for a more combustible ceiling.
- Don’t exceed the accepted temp limit for your wood stove. This temperature is higher for pellet stoves.
Different Types Of Drywall
There are many different types of drywall board products.
Each has its specific fire safety rating and will get damaged at different temperatures.
They also have different ratings for how fire-resistant they are.
If you are implementing a new build on the house, this is an important consideration.
This is especially true if you install drywall near a fireplace, wood-burning stove, or pellet stove.
We all want our homes to be as safe as possible, so using the most fire-safe materials for combustible wall surfaces in locations subject to extreme temperatures will give us more peace of mind.
Some people think thickness directly correlates to the fire safety rating of the drywall.
This is not the case as some thick materials are more flammable than thinner varieties of fire-rated gypsum boards.
It’s best to look at the official fire rating from the specific drywall manufacturer you’re using to know exactly what you’re working with as far as temperatures go.
One Hour Drywall
One hour of drywall is rated to resist succumbing to fire for one hour.
If the wall has a one-hour rating, it will continue to bear its full load for an hour after the wall has caught on fire.
This is important as it gives you how much time you have to escape a house fire before the wall collapses.
Two Hour Drywall
Two-hour drywall is rated to resist succumbing to fire for two hours.
The 2-hour rating resists collapse for two hours after catching on fire.
This type of 2-hour firewall will cost more than other varieties but is worth the extra peace of mind.
There is also a 3-hour firewall if you want to extend this time even more.
Standard ½” Inch Drywall
Standard ½” inch drywall has a 30-minute rating for fire protection.
This means the standard ½” inch drywall will only last 30 minutes before collapsing due to fire.
There are ⅝” inch varieties, also called “fire-code” drywall, which have a 1-hour rating for fire.
Fireproof drywall is ⅝” inch thick drywall.
It is also called ⅝” inch, type x gypsum board.
It is made of different non-combustible materials to make it more resistant to catching on fire.
This type adheres to different code requirements for fire-safe builds.
The multi-layered fireproof drywall incorporates glass materials into the drywall to help retard fire.
In general, this type of drywall is denser than gypsum board varieties.