How to Fireproof Wood

Flames can quickly destroy everything in their path, leaving behind a trail of devastation and despair. Fortunately, there are ways to prevent fires from spreading, and one of the most important is by fireproofing wood. 

You don’t have to have been an Eagle Scout to know that wood is flammable, but you may not know that there are ways to prevent a single spark from spreading–quite literally– like wildfire. So we’re going to tell you the most effective ways for how to fireproof wood, whether you’re looking to protect your home, outdoor structures, or business. 

Before we cover the different techniques for fireproofing wood, let’s go over what fireproof wood is.

What Is Fireproof Wood?

Fireproof wood, also known as flame retardant wood, is a specially treated wood that has been designed to resist the spread of fire. This type of wood has been treated with a variety of fire-retardant chemicals that can help slow down the combustion process and prevent the wood from igniting. 

Can You Make 100% Fire-resistant Wood?

We need to clarify what we mean when we use the word “fireproof” in this context. Fireproofing wood doesn’t make the wood immune from catching a flame. It does, however, protect the wood from heat and significantly slow down the time it takes for the wood to burn. 

You can think about fireproof wood like the flu vaccine. When you get a flu shot, it doesn’t turn you into a superhero who’s untouchable from any flu virus (as much as we’d like it to). Rather, it mitigates the risk of you catching the flu by making it more difficult for the virus to wreak havoc on your immune system.

In short, there’s no such thing as 100% fire-resistant or heat-resistant wood. Fireproofing wood is like getting the flu shot. It may not be a cure-all, but it sure can make a difference should disaster strike.

How to Fireproof Wood with Different Techniques

There are several methods and techniques for creating the fire resistance of wood, ranging from simple DIY solutions to more complex industrial processes.

How to Fireproof Wood with Intumescent Paints

A popular method for how to make wood fireproof is to use intumescent paints. These paints can swell and expand when exposed to high temperatures. As a result, their expansion creates a thick layer of foam that helps protect the wood from heat and slows down the spread of flames.

How to Fireproof Wood with Fire-retardant Sprays

Fire-retardant sprays and chemicals are treatments that can be applied directly to the surface of the wood or added to the wood during the manufacturing process. These particular chemicals work by inhibiting the combustion process, making it more challenging for flames to attach and spread.

The distance that you should stand when you spray fireproofing onto wood can vary depending on the type of spray gun or equipment being used, as well as the specific fireproofing material being applied. In general, it’s recommended that you stand at a distance of at least 18 inches away from the surface being sprayed to ensure even distribution of the material and minimize overspray.

How to Fireproof Wood with Fire-retardant Coatings

One of the most common “How to fireproof wood” techniques for DIY folks is using fire-retardant coatings. These coatings are applied to the surface of the wood to create a protective barrier against flames, creating a “wood fire resistance” effect. A fire-retardant coating works by releasing a gas that helps cool down the surface of the wood. As a result, it’s more difficult for flames to take hold of the wood.

How to Fireproof Wood with Fire-resistant Building Materials

Using fire-resistant building materials, such as brick, stone, or concrete, can be an effective way to fireproof wood structures. These materials are inherently resistant to fire, and incorporating them into the design of your building can create a barrier against flames and reduce the risk of fire damage.

For example, using a brick or stone veneer on the exterior walls of a wood-framed building can help protect the structure from flames and reduce the risk of fire spreading from outside to inside. Similarly, using concrete for the floors and walls of a building can provide a strong and fire-resistant foundation that can help prevent fire from spreading throughout the building.

Is There Such a Thing as Non-combustible Wood?

Now that you understand how to fireproof wood, let’s talk about types of wood that don’t need as thorough fireproofing. While wood is naturally combustible, some types of wood are less likely to catch fire than others.

Treated Lumber

Treated lumber is a type of wood that has been chemically treated with fire-retardant substances to enhance its fire resistance properties. These chemicals work by penetrating the wood fibers and reacting with the wood to form a protective layer on the surface of the wood. The layer helps to slow down the combustion process and reduces the amount of heat released during a fire.

Ammonium Sulfate-treated Lumber

Ammonium sulfate-treated lumber is a type of treated lumber that’s used to enhance the fire resistance properties of wood. This fire-rated wood is treated with ammonium sulfate, which reacts with the wood fibers to create a char layer on the surface of the wood. The char layer helps to minimize the spread of fire by lengthening the time it takes for the wood to burn.

Borate-treated Lumber

Borate-treated lumber is another type of treated lumber that’s commonly used in construction. This type of wood is treated with borate compounds, which work by penetrating the wood and disrupting the natural combustion process. As a result, the treated lumber becomes flame-retardant wood.


Hardwood is a type of wood that’s known for its natural fire-resistant properties. One of the reasons hardwood is more fire-resistant than softwood is that it’s denser and has a lower moisture content. The density of hardwood makes it more difficult for flames to penetrate the wood fibers and ignite the wood, while the lower moisture content makes it less susceptible to catching fire.

Likewise, hardwood is less likely to produce flames and embers than softwood when it’s burning. This is because the cellular structure of hardwood is more compact, which makes it more difficult for flames to penetrate the wood fibers and cause a chain reaction of combustion.


Mahogany is a dense hardwood that’s known for its high resistance to fire due to its natural composition. This type of hardwood contains a high amount of tannins and oils, which help to make it more resistant to fire. Moreover, these natural compounds can create a layer of char on the surface of the wood when exposed to heat, which can help to protect the wood from further damage.


Oak is arguably the most fire-resistant wood due to its high lignin content. Lignin is a polymer found in the cell walls of plants, and it’s responsible for providing structural support to the plant tissue. As oak contains a higher percentage of lignin than most other hardwoods, it’s more difficult to burn and more resistant to fire.

So how exactly does lignin work to create a fire-resistant effect? Well, when exposed to heat, lignin in oak forms a layer of protective carbon on the surface of the wood. This layer of charred wood acts as a protective barrier that insulates the interior of the wood from the heat of the fire. The carbon layer also reduces the amount of oxygen available to the fire, further slowing down the combustion process.

How to Fireproof Wood: The Bottom Line

Fireproofing wood is a crucial step in safeguarding your property against the devastating effects of fire. Whether you’re protecting your home, business, or outdoor structures, the right fireproofing techniques can make all the difference in preventing a disastrous blaze. By following the tips outlined in this article, you can take proactive steps to fireproof your wood and enjoy peace of mind knowing that your property is better protected

So don’t wait until it’s too late–start fireproofing your wood today and help keep your home and loved ones safe.