The key feature of intumescents is that they expand significantly when exposed to high temperatures, such as those found in a fire. Some intumescent products can expand to more than 100-times the original thickness. As the product expands it becomes much less dense, which makes it act as in insulator that keeps the high temperatures away from structural members.

Code Issues and Proper Listings

In the United States, both the International Building Codes (IBC) and the Life Safety Code (NFPA 101) provide criteria for proper fire protection. It is critical that architects understand the requirements when determining where protection is needed and when selecting the type of protection to be used. In addition, many jurisdictions have special requirements that go beyond the IBC and NFPA. Even some insurance companies have specific requirements. ***Please refer to local codes or seek advice from a code consultant before using any of this information.

All fireproofing must be tested and must have the proper listing. A UL label is usually required for fire protection assemblies in the United States. Fireproofing of structural members is usually accompanied by certificates and reports of the installation for the owner to keep on file. A properly trained and certified installer must be used for these products.

How Intumescent Products Work

Intumescent products are made of a series of chemicals suspended in a binder. When the binder is exposed to heat it begins to soften, which allows the suspended chemicals to the heat. The chemicals begin to react, which releases vapors that create a foam. A carbonization occurs and the foam solidifies into a black insulating material that is often referred to as char.

The video below shows how the intumescent paint expands to provide protection from heat. It is important to note that the product is not burning. Instead, a chemical reaction is taking place that builds up an insulating material that protects the underlying material from the heat.