Whether you’re designing with spray-foam insulation or reviewing fireproofing requirements, thermal barriers are a central component of code compliance. These systems slow the spread of fire and protect structural materials from heat, helping maintain building integrity long enough for safe evacuation.
Here, we answer some of the most common questions builders, inspectors and homeowners ask about thermal barriers — and explain how products like IFTI’s DC315 and DC360 meet these essential safety requirements.
What is a Thermal Barrier?
A thermal barrier is a protective material applied over combustible components, such as spray polyurethane foam (SPF), that slows heat transfer during a fire. Its purpose is to prevent the underlying material from igniting for at least 15 minutes, allowing time for detection, evacuation, and response.
Thermal barriers are recognized by codes such as the International Building Code (IBC) and International Residential Code (IRC) and must meet strict testing criteria, including NFPA 275. The IBC and IRC also include compliance pathways for alternative thermal barriers tested to NFPA 286.
IFTI’s DC315 is one of the most widely used and tested alternative thermal barriers in North America, providing verified protection for SPF insulation in both residential and commercial assemblies.
What is a Thermal Barrier for Spray Foam?
In spray foam applications, the foam insulation itself is highly combustible, which makes a thermal barrier mandatory under building codes. The barrier—often gypsum board or a tested intumescent coating—acts as a heat shield between the insulation and the building interior.
DC315 is specifically designed for this use. It’s a single-component, water-based intumescent coating that can be spray-applied directly over cured foam. When exposed to fire, it expands and forms a tough, insulating char that prevents the foam from reaching ignition temperature.
Because DC315 is tested under NFPA 286 and listed in ICC-ES ESR-3702, it is approved as an alternative thermal barrier that meets the 15-minute protection requirement established in IBC Section 2603.
What Can Be Used as a Thermal Barrier?
Acceptable thermal barrier materials include both prescriptive and tested alternative systems:
Prescriptive barriers: ½-inch gypsum drywall, plaster or concrete coatings that inherently meet the 15-minute protection standard.
Alternative barriers: Tested assemblies using intumescent coatings such as IFTI’s DC315, proven to match or exceed the performance of drywall through large-scale fire testing.
Alternative barriers are particularly useful in irregular spaces—such as attics, crawl spaces, or industrial applications—where drywall installation is impractical.
Is Drywall Considered a Thermal Barrier?
Yes. ½-inch gypsum wallboard is a common and code-recognized thermal barrier. It provides reliable protection and is used as the baseline in most fire testing standards.
However, when drywall can’t be installed, coatings such as DC315 are tested to ensure they provide at least the same thermal protection level. These coatings simplify installation, especially on curved, vertical or overhead surfaces.
What is a 15-minute thermal barrier?
A 15-minute thermal barrier is a system tested to delay the temperature rise of underlying combustible materials by at least 15 minutes under standard fire exposure. This is the minimum performance level required by building codes for foam insulation.
In practice, that means a properly applied DC315 coating performs the same protective function as ½-inch drywall—meeting or exceeding the 15-minute benchmark through verified large-scale testing.
How to Create a Thermal Barrier
Creating an effective thermal barrier starts with using tested, code-approved products and following manufacturer instructions precisely. Key steps include:
- Ensuring the substrate is clean, dry and properly cured
- Applying the coating to the correct wet and dry film thickness
- Using manufacturer-specified spray or roller equipment
- Verifying film thickness with calibrated gauges after curing
For additional protection of wood, gypsum, or mixed-material assemblies, IFTI’s DC360 can be used as a Class A-rated intumescent coating, extending fire resistance beyond the insulation system.
Why Tested Coatings Matter for Fire Safety
Unlike traditional materials, intumescent coatings such as DC315 and DC360 are designed, tested, and certified as complete systems. Each product includes supporting documentation, test results, and evaluation reports to simplify code compliance and inspection.
These coatings not only meet building code requirements—they also support sustainability and design flexibility by allowing open designs and exposed finishes without sacrificing safety.
IFTI provides tested, certified intumescent coatings that meet modern, international code requirements for alternative thermal and ignition barriers. Whether your project involves spray foam, timber or composite structures, our coatings offer proven performance backed by decades of testing.
For technical documentation or application guidance, contact IFTI’s technical team.