Yes, polyurethane foam is highly flammable. Both rigid and flexible forms ignite easily, burn rapidly, and produce intense heat along with dense, toxic smoke. This makes it one of the more dangerous common materials in a fire, whether it’s in your couch cushions, mattress, or the insulation inside your walls.
How Polyurethane Foam Burns
Polyurethane foam burns fast and hot. In fire testing, polyurethane foam releases heat at roughly 560 kilowatts per square meter, which is significantly more than wood. That intensity means a foam-filled couch or mattress can go from a small flame to a fully involved fire in just a few minutes, far faster than furniture made with natural materials like cotton batting or wool.
The foam’s open-cell structure is part of the problem. All those tiny air pockets give fire easy access to oxygen, which accelerates combustion. Once ignited, the foam melts into a liquid that continues to burn, pooling and spreading the fire to surfaces below it. This melting behavior is especially dangerous because it can carry flames to areas the original ignition source never touched.
Toxic Gases Released During Burning
The smoke from burning polyurethane foam is far more dangerous than ordinary wood smoke. When the foam breaks down in heat, it releases carbon monoxide, hydrogen cyanide, benzene, toluene, nitrogen oxides, acetaldehyde, and acetone, among other compounds. Carbon monoxide is typically the most abundant and is responsible for the majority of fire deaths overall, but hydrogen cyanide is particularly concerning because it’s extremely toxic even in small concentrations and acts fast, impairing your ability to escape.
This cocktail of gases is a major reason why modern house fires are more lethal than fires decades ago. Homes today contain far more synthetic foam in furniture and bedding, which means occupants have less time to escape before smoke becomes incapacitating. OSHA has specifically flagged the fire hazard of polyurethane foam in both construction and maritime settings because of these combustion byproducts.
Flame Retardants in Foam Products
Most polyurethane foam sold in furniture and baby products contains chemical flame retardants designed to slow ignition. The most common class is chlorinated organophosphate flame retardants. A study analyzing 101 foam samples from baby products found these chemicals in about 60% of samples. The single most frequently detected compound, TDCPP, appeared in 36% of products tested.
These additives don’t make foam fireproof. They buy extra seconds before ignition, which can matter in a real fire, but the foam still burns once flames take hold. The trade-off has been controversial: many of these chemicals have raised health concerns because they migrate out of foam over time and accumulate in household dust. California’s original flammability standard (TB 117) effectively required flame retardant chemicals in furniture foam for decades, which drove their widespread use across the entire U.S. market since manufacturers didn’t want to produce separate product lines for one state.
How Flammability Standards Have Changed
In 2013, California replaced its open-flame test with a new standard, TB 117-2013, that only tests resistance to smoldering ignition sources like cigarettes rather than open flames. Under this standard, foam and fabric assemblies are exposed to a lit cigarette and monitored for 45 minutes. A material fails if it keeps smoldering after the test period, chars more than about 1.5 to 2 inches depending on the component, or transitions to open flaming. This shift was significant because meeting the smoldering test generally doesn’t require chemical flame retardants, allowing manufacturers to produce foam without them.
For mattresses, the federal standard is stricter. The Consumer Product Safety Commission requires that mattress sets keep their peak heat release below 200 kilowatts at any point during a 30-minute open-flame test, and total heat release must stay under 15 megajoules in the first 10 minutes. Manufacturers typically meet this by wrapping foam cores in fire-resistant barrier fabrics rather than loading the foam itself with chemicals.
Spray Foam Insulation in Buildings
Spray polyurethane foam used as building insulation is the same basic chemistry as the foam in your furniture, and it carries the same fire risks. Building codes address this with strict requirements. Under the International Building Code, foam plastic insulation in commercial buildings must have a flame spread index below 75 and a smoke developed index below 450, as measured by the ASTM E84 tunnel test. For exterior walls, the limits tighten to a flame spread index below 25.
Because spray foam is combustible, building codes generally require it to be separated from the interior of a building by a thermal barrier, typically half-inch gypsum drywall. The drywall acts as a shield, keeping the foam from being exposed to an interior fire long enough for occupants to escape. Foam can be left exposed only if it passes specific large-scale fire tests proving it won’t contribute to dangerous fire spread.
Any wall assembly that needs a fire-resistance rating must maintain that rating with the foam plastic in place. This means the foam can’t compromise the wall’s ability to contain a fire for its rated duration. Contractors who skip the thermal barrier or install spray foam in ways that violate code create a serious hidden hazard, one that may not become apparent until a fire occurs.
Practical Safety Considerations
If you have older upholstered furniture, especially pieces made before 2014, the foam likely contains chemical flame retardants but is still highly flammable once those retardants are overwhelmed. Newer furniture may skip the retardants entirely, making it arguably more flammable in an open-flame scenario but less of a chemical exposure concern day to day. Either way, polyurethane foam furniture should be kept away from open flames, space heaters, and candles.
Working smoke detectors are especially important in homes with foam-filled furniture and mattresses. The speed at which polyurethane foam burns means the window for safe escape is measured in minutes, not the 15 to 20 minutes that older studies based on natural-material furnishings suggested. Modern fire research consistently shows that flashover, the point where an entire room ignites, can occur in under five minutes in rooms furnished with synthetic foam products.