Insulation is a critical part of any structure. It keeps your home protected from the elements and can make a big difference in your home’s energy efficiency — but there’s even more to know about insulation and structural safety.


Depending on your ceiling insulation type, the raw materials can be flammable and cause a fire hazard in the right circumstances. In addition, insulation is often located next to appliances and utility access points, which can be a high risk for fire ignition. 


Luckily, most building codes require that insulation be protected with a barrier so that even if your insulation catches fire, you’ll be protected.

What Is an Insulation Barrier?

If you’ve ever seen the insulation in your home, it may appear that nothing is separating it from the next room. However, building codes require some sort of barrier to protect structures in case of fire. 


An insulation barrier is a protective material or coating that is intended to keep a fire or heat source contained in the insulated space rather than spreading to the rest of the structure. The two primary types of heat-related insulation barriers are thermal and ignition.

Thermal vs. Ignition Barriers

A thermal barrier is a material placed between the insulation and living space to delay temperature rise and prevent flames from spreading if the insulation catches fire. Thermal barriers can contain fires entirely or slow the spread of the fire significantly, depending on the circumstances. 

Without a thermal barrier, a fire in an insulated attic or crawl space can easily and quickly spread to living areas of the home. Even when thermal barriers don’t stop a fire from spreading completely, the delay provided by the barrier can mean the difference between life and death. 

Thermal barrier materials are made according to very specific standards. Before being approved for market use, they must pass a number of tests, including a temperature test and fire integrity test, to ensure they stay in place and do their job. 

An ignition barrier is a material added to the insulation itself to make it unable to ignite when exposed to a flame or heat source. Usually, the ignition barrier is applied as a coating onto the insulation itself. When the barrier is exposed to a flame or heat, the ignition barrier expands and protects the area from spreading fire.

Like thermal barriers, ignition barrier materials must pass rigorous standards testing to ensure they work predictably and consistently. Ignition barriers slow the spread of fire or may even prevent insulation from catching fire entirely, but they do not provide any protection from spaces adjacent to the insulation.

What Type of Ceiling Insulation Do You Need?

Building codes, including your community’s local code, will govern whether you need a thermal barrier or ignition barrier. As a general rule, thermal barriers must separate occupied spaces from insulated spaces. However, there are certain exceptions. 

The primary exception is spaces that are not intended to be occupied but will only be used by a professional when servicing utilities. If these areas are going to be used for storage of any kind, a thermal barrier is required. 

So unless your attic or crawl space is unoccupied and used exclusively for servicing utilities, you’ll likely need a thermal barrier. 

As a homeowner, it’s good to be informed about what insulation is in your home. However, your insulation contractors are experts and will be able to determine what type of insulation is required for your space. 

They can help you understand the different types of insulation barriers and insulation materials so that you have complete confidence that your home is protected.