Ignition Barrier vs Thermal Barrier: What’s the Difference?

Fire safety is not as simple as keeping your fire extinguisher charged and ready. Many steps toward fire safety are put in place before anyone moves into a home. This can include things like proper wiring and putting barriers in place between flammable insulation and a building’s interior.

When building or remodeling, one of the most important fire safety decisions you will have to consider is the use of an ignition barrier vs thermal barrier. Both can be very important factors in keeping your family and friends safe, but they have some key differences.

The choice between the two often comes down to building codes, room usage, and other factors. Each kind of barrier is a valuable fire protection tool, though. So what are they and how do you know when you need one?

Knowing the Difference

To understand the ignition barrier vs thermal barrier divide, it’s important to understand where they get used. Each type of barrier has to do with insulation— specifically, sprayable polyurethane insulation foam.

This kind of insulation has become the insulation of choice for many construction firms in both residential and commercial properties. The only problem with it is that it is combustible, which is why barriers are put in place for protecting the area being insulated.

Building codes can vary from state to state, so if you are planning a construction or remodeling project, be sure to look up what you’ll need to stay in compliance with your local fire safety protocols.

Thermal Barriers

As we examine the ignition barrier vs thermal barrier divide, we will start with the one that is most common in any given building. The chances are good that, no matter where you are reading this, there is a thermal barrier near you.

In any room that will be used regularly by residents, you need a thermal barrier. That means that if people spend time in a space, or people may spend time in a space, it needs a barrier. That includes spaces used for storage.

Thermal barriers are materials that separate insulation from the interior of a room. They need to be a certain thickness so that, if there is a fire inside the walls, that fire is slowed down. That allows the people in the building more time to put their fire evacuation plan into effect.

Thermal barrier materials are all fairly common building materials. In general, a thermal barrier will be at least half an inch thick. The fire rating of half inch thick gypsum is the baseline rating for what is thermal barrier acceptable.

Common materials used as thermal barriers are gypsum, drywall, plywood, or even some specially designed paints. The important thing about each of these thermal barriers is that they delay fire from getting either from an inhabited space to your insulation or from your insulation to an inhabited space.

Ignition Barriers

Less common is the ignition barrier. Most building codes require thermal barriers in between the habitable side of a room and the insulation. For rooms that will not be used for storage or personal use, ignition barriers are required.

An ignition barrier is added to spray-applied polyurethane insulation foam to prevent it from igniting. Basically, when the insulation is exposed to fire, the ignition barrier expands and forms a char barrier. This only makes the insulation resistant to ignition, not immune from it. But it can make all the difference in the world.

Common spaces that will feature ignition barriers are attic and crawl space areas. However, if you use these spaces for storage, you need to put in thermal barriers. If you only use those spaces for servicing utilities, an ignition barrier is sufficient.

If a building’s plans include an inaccessible area, that area can use an ignition barrier. If there is a space specifically for mechanicals to be brought in and serviced but not stored, that space can use an ignition barrier.

Generally speaking, though, if people or things will be kept in a room, an ignition barrier just will not be enough. That room will require a thermal barrier.

Ignition Barrier vs Thermal Barrier

When you consider the ignition barrier vs thermal barrier usage discussion, it boils down to a pretty simple difference. An ignition barrier is added to insulation, while a thermal barrier is a physical object that is placed between the insulation and occupied spaces.

There is nothing that says that insulation with an ignition barrier cannot be put behind a thermal barrier. But thermal barrier insulation situations do not require an ignition barrier. So when you look at the insulation you will be using, know what you’ll need to do to be compliant with fire codes.

Follow the Fire Code

Always remember: if you are not sure what kind of barrier you need in a given space, check the fire code requirements. Generally speaking, if people or things will be in a room for an extended period of time, you need thermal barriers.

That’s really how simple the ignition barrier vs thermal barrier debate is. If people use the room for anything other than servicing utilities or mechanical things, that room needs thermal barriers between the insulation and the people using the room.

Even if a room’s primary use is storage, like an attic, it needs thermal barriers. If nothing is stored there, ignition barriers are fine. Though the building codes in your area could be different. If you are doing a remodeling project yourself, check your local fire codes. If you are hiring contractors, they should already know what needs to be done.

Just be careful and use your best judgment! That’s what fire safety is all about.