Spray foam insulation (spray polyurethane foam, or SPF) is prized for its energy efficiency, but it is not fireproof. A recent report by industry experts notes that “spray polyurethane foam… is a combustible material”. In other words, spray foam will burn if exposed to enough heat or flame. Modern SPF formulations include flame retardants to slow ignition, but by itself spray foam is still a plastic foam that burns. This means you cannot rely on SPF alone as “fireproof insulation.” Any exposed foam must be protected by a certified fire-retardant barrier.
Building Codes: Thermal and Ignition Barriers
Building codes reflect this requirement. Both the International Building Code (IBC) and International Residential Code (IRC) mandate that all foam plastic insulation be separated from occupied spaces by an approved thermal barrier (typically a 15‑minute gypsum board such as ½″ drywall). The Spray Polyurethane Foam Alliance (SPFA) explicitly states that SPF “must be separated from the interior spaces with a 15-minute thermal barrier”.
In practice, this means standard drywall or an equivalent approved covering must hide the foam. In special cases like attics or crawlspaces accessed only for utilities, an ignition barrier can substitute (such as mineral wool, wood panels, or certain coatings), but even this is tightly regulated. Crucially, the IBC/IRC allow specially tested intumescent coatings as alternate barriers. If an intumescent paint passes the required fire tests, it can replace drywall as the protective layer over spray foam. In short, codes do not permit exposed SPF without protection.
Intumescent Coatings: Fire-Retardant Protection
Intumescent coatings are the approved solution for making spray foam fire-retardant. These are specially formulated paints that char and expand when heated, creating an insulating layer that slows flame spread. Coated SPF will resist ignition much longer than bare foam, but it is still not “fireproof” – it just provides a critical delay.
For example, IFTI’s DC315 is a water-based intumescent coating designed specifically for SPF. Applied at the proper thickness, DC315 gives spray foam a tested 15-minute thermal barrier (comparable to ½″ drywall) as required by code. (IFTI’s DC360 is a similar intumescent coating used for wood or gypsum surfaces.) When intumescent paint is applied correctly, it makes the foam meet fire-performance standards. However, only coatings with valid certifications – such as ICC-ES reports under AC377/AC456 – can be used as an alternative barrier.
Beyond the “Fireproof Insulation” Myth
It’s important to realize that no common insulation is truly fireproof. Even mineral wool or fiberglass only resist fire up to their own limits – they don’t turn into stone during a blaze. Spray foam, being a plastic foam, is inherently combustible like many other building materials. Marketing the foam as “fireproof” is misleading and dangerous.
The correct terminology is “fire-retardant” or “flame-resistant when coated”. Homeowners and contractors should always assume foam can burn if not properly protected. By insisting on code-compliant barriers (whether gypsum or intumescent paint), you ensure the insulation meets the same safety standards as other building materials.
For projects needing a safe, code-compliant spray foam installation, consult IFTI. Our experts can help you determine the right coating and thickness for your application.
If you have questions about products or installation, contact IFTI and our technical team will guide you through compliance and best practices.