Wood fire protection is important in making the structures we live and work in safer. When it comes to fire, minutes matter. Fireproofing wood can make it more fire resistant. If a fire breaks out, this resistance can buy the necessary time to get the fire under control before it turns into a catastrophe. Fireproofing wood can limit damage and save lives. Let’s take a look at how to make wood fire resistant with fire proof treatments and coatings.
Defining Terms: Fire Resistant and Fire Retardant
The terms fire resistant and fire retardant are often used to describe products that can slow down the spread of fire within a structure. Most wood can catch fire under the right conditions. In fact, if a fire breaks out, wood often serves as fuel. By fireproofing wood used in construction, its usual flammable make up can be altered. This fire-resistant wood can then withstand the heat and flame output of a fire under certain conditions and within a certain timeframe.
Fire retardant wood means that it has been treated with a substance that will actively slow down the spread of fire by reducing a fire’s intensity and depriving it of fuel. Much like covering a building’s structural elements with fire retardant panels, such as gypsum or magnesia boards, using fire-retardant products to fire-treat wood can help wood construction materials contain a fire more easily. This slowing down of a fire’s spread expands the timeframe to both fight and escape it.
Heat resistant wood means that it will maintain its normal properties under high temperatures, but this does not mean it will not succumb to fire. Looking at how to make wood heat resistant should also include looking at making it fire resistant.
Fireproofing Wood: Is It Possible?
Although all wood is flammable, not every type of wood burns the same. There are more naturally fire- resistant woods than others. Hardwoods, such as oak, walnut, mahogany, maple, and teak, are considered the most fire-resistant wood because they are denser, therefore they burn more slowly. Their denser structure also make hardwoods grow slower and more difficult to work with, which also makes them cost more as a construction material. Hardwoods are most often used in exterior construction.
Softwoods, such as pine, cedar, and fir have a less dense structure and therefore burn faster and are more susceptible to fire. These woods also grow faster, are less expensive, and easier to use than hardwoods. Softwoods are the most common wood building material for interior construction, despite their flammability.
Fireproofing wood with a fireproof wood treatment can decrease the flammability of these softwoods, making this common construction material safer. The wood, however, is never completely fireproof, as in, never catching fire or burning. The fireproofing process makes wood more fire resistant through the use of fire-retardant products. These fire-retardant wood building materials can then construct interiors that are both slower to catch fire and to spread it.
How to Fireproof Wood
There are several different ways for fire proofing wood to be used in building construction. These processes are either treating the wood itself or applying treatments to the wood’s surface. The purpose of these different processes for fireproofing wood include:
- Slowing down the possibility of a fire igniting
- Protecting the structural properties of the wood as a building material
- Protecting the structural integrity of the building
- Reducing the temperature of the heat released during combustion
Fire Resistant Lumber or Plywood
Fire-resistant wood treatment can turn highly flammable lumber or plywood into a more fire-resistant building material. The cut wood is first kiln-dried and then pressure treated with fire-retardant chemicals. This high-pressure system is used to infuse the fire-retardant chemical into the wood to fully incorporate it into the wood’s structure. Using this high-pressure fire treatment for wood makes it resistant to fire ignition and high temperatures.
Fire resistant lumber and plywood is fire-treated during manufacturing to be used as fire-resistant construction materials. The wood is tested and labeled, typically as Fire Retardant Treated Wood (FRTW). To be FRTW labeled, treated wood needs to meet standards related to the rates of fire ignition and fire spread as well as smoke generation. These ratings are important because they measure the elements of a fire that are in direct relation to people safely being able to escape a burning building, including how fast a fire starts, how fast it spreads, and the amount of smoke present.
Fire Resistant Coatings
Unlike fire treatments that infuse into the wood’s structure, fire resistant wood coatings are applied to the wood surface to help it more easily resist a fire’s intensity, slowing its spread. Most fireproof coating for wood is a type of intumescent paint. When heated or exposed to flames this fire-resistant paint expands into a chemical foam that insulates wood by creating a char barrier against a fire’s heat and flame. This protects the wood from burning.
These fire-resistant paints are tested and certified to measure the length of time it takes for the protective barrier they create to fail under extreme heat and flame. They are given a fire rating, between 30 minutes to about 2 hours, based on this failure time frame. This is the extended window to get the fire under control or escape.
Fire Retardant Paints
While fire resistant coatings, like intumescent paint, create a barrier that protects the wood itself, fire-retardant paints contain chemicals that slow down the fire itself. These paints are not designed to protect the wood but to slow down the spread of fire by depriving it of fuel. Fire retardant paints are not a fireproofing process for wood but are a fire protection measure.
Eco-Friendly Wood Fireproofing
A more recent trend in fireproofing wood is a modified use of an old Japanese wood fireproofing method called shou sugi ban. This method, first developed in Japan in about the 1700s, increases the durability of wood to resist fire through a charring process. Wood is controllably charred with a blowtorch, which forms a hard shell that is sealed with a plant-based oil to create a naturally protective layer over the wood. Although first developed to protect cedar planks, the process is successful with a wide range of woods, including pine. This fireproofing method is based on the science of how wood burns in stages. Cellulose is the first part of wood to catch fire and it burns quickly, leaving behind charcoal, which takes higher temperatures and more time to burn. By burning off the cellulose layer and leaving the char through the shou sugi ban method, wood becomes naturally more fire resistant, just like charcoal.
The Last Word on Fireproofing Wood
A wood fire proofing treatment can go a long way in making the places you live and work in safer. Wood is a highly popular construction material, but it is also a highly flammable material. Fireproofing wood lowers the flammability of wood and can create wood that is more fire resistant. Fire treated wood and fire-resistant coatings can help prevent a fire from spreading and destroying a building’s structural integrity. If fire strikes, this can mean the buying of the minutes needed to prevent complete destruction and devastation.