Is Polyurethane Flammable: Can It Catch Fire or Combust?

Polyurethane is a versatile material used in everything from furniture and insulation to coatings and adhesives. But when it comes to fire safety, questions arise:

Is polyurethane flammable? Is it combustible like wood or paper?

Understanding the fire behavior of polyurethane foam, liquids, and other forms is crucial for safe handling and peace of mind. This article will delve into the flammability of polyurethane, exploring its characteristics and offering insights for responsible use.

Is Polyurethane Flammable?

Yes, polyurethane is flammable. Polyurethane is a thermoset plastic that can initially char in a fire but will ignite and burn if exposed to an intense heat source.

Is Polyurethane Combustible?

Polyurethane is combustible and can sustain burning once ignited. Polyurethane is an organic material that can burn rapidly and produce dense smoke, gases, and intense heat during combustion.

Polyurethane in can

What Is Polyurethane Made Of?

Polyurethane is a combination of two main components: isocyanates and polyols. These react to form a polymer with various properties, depending on the specific formulation.

  • Isocyanates: Reactive organic chemicals containing the isocyanate functional group (-N=C=O). They readily react with other compounds containing hydroxyl groups, and this reactivity is the basis for polyurethane production.
  • Polyols: Compounds containing multiple hydroxyl groups (-OH). In polyurethane production, these hydroxyl groups react with isocyanates, forming the long-chain molecules that give polyurethane its unique properties.

Polyurethane Flash Point

The flash point of polyurethane ranges from 82°F to (38°C to 200°C), depending on the type of polyurethane material.

Here are some examples:

  • Polyurethane coating: 82°F (38°C)
  • Polyurethane foam: 199°F (93°C)
  • Polyurethane resin UR5041: 262°F (128°C)
  • Polyurethane resin UR5041B: 392°F (200°C)

What Temperature Does Polyurethane Ignite?

Polyurethane can ignite within the temperature range of 500°F to 750°F (260°C to 400°C), depending on the specific type, density, and presence of flame retardants.

What Temperature Does Polyurethane Melt?

Polyurethane generally starts to melt around 300°F to 400°F (150°C to 200°C), well below its ignition point.

Is Polyurethane Flammable When Dry?

Polyurethane is flammable when it is dry. Whether dry or wet, when exposed to a strong enough heat source, polyurethane will burn, releasing significant heat and potentially toxic fumes. Flammability is inherent to the material itself.

Can Polyurethane Be Flame Retardant?

Yes, polyurethane can be flame retardant. Manufacturers often add specific chemicals during production to enhance polyurethane’s fire resistance. These additives help delay ignition, reduce flame spread, or even self-extinguish.

Note: Flame retardancy does not guarantee fire safety. Even treated polyurethane can burn under extreme heat or prolonged exposure to fire.

Flammable polyurethane foam

Common Polyurethane Types and Their Flammability

Polyurethane Foam flammability

Polyurethane foam (FPF) is flammable and should be kept away from heat sources and open flames. When ignited, FPF can burn rapidly and produce intense heat, dense smoke, and toxic gases such as carbon monoxide, benzene, toluene, oxides of nitrogen, hydrogen cyanide, acetaldehyde, acetone, propene, carbon dioxide, and alkenes.

Water-Based Polyurethane flammability

Water-based polyurethane is generally not flammable because it’s mainly made of carbon, hydrogen, and oxygen.

Oil-Based Polyurethane flammability

Oil-based polyurethane is highly flammable and should be kept away from heat sources and open flames. Oil-based polyurethane is made with toxic and flammable solvents that help the urethane resin form into a cured film.

Polyurethane Insulation flammability

Polyurethane insulation is a flammable material. Polyurethane insulation can ignite from a small fire source and burn at high rates.

Safety Precautions for Using Polyurethane

Before and During Use

  • Work in a well-ventilated area: Ensure proper ventilation to avoid inhaling harmful fumes from polyurethane or its solvents.
  • Maintain a clean workspace: Keep the work area free of flammable materials like rags, solvents, or debris that could easily ignite.
  • Use proper personal protective equipment (PPE): Wear gloves, safety glasses, and a respirator if recommended for the specific product you’re using.
  • Follow manufacturer’s instructions: Carefully read and adhere to all safety precautions and instructions provided by the manufacturer on the product label and safety data sheet (SDS).
  • Never smoke or use open flames near polyurethane: This includes cigarettes, lighters, torches, or any other ignition source.
  • Have a fire extinguisher readily available: Keep a suitable fire extinguisher nearby in case of accidents. Be sure the extinguisher is properly charged and you are familiar with how to use it.


  • Store polyurethane in a cool, dry, and well-ventilated location: Avoid storing it near heat sources, direct sunlight, or open flames.
  • Keep containers tightly sealed when not in use: This prevents excessive evaporation of solvents and exposure to moisture that could affect the product’s properties.
  • Store polyurethane away from incompatible materials: Do not store polyurethane near strong oxidizing agents, acids, or bases, as these can react dangerously.

Additional Tips

  • Dispose of rags and other used materials properly: Soak used rags in solvent (following proper disposal guidelines for the solvent) and dispose of them safely in a designated metal container with a lid.
  • Be aware of the local fire codes and regulations: These may have specific requirements for handling and storing flammable materials like polyurethane.

Remember: Always prioritize safety when working with polyurethane. If you are unsure about any aspect of its use or storage, consult the manufacturer’s information or a qualified professional.


While polyurethane offers valuable properties in various applications, it’s essential to remember that polyurethane is flammable and combustible. This applies to all forms that are not water-based, including foam, insulation, coatings, etc.

Always prioritize safety by handling and storing polyurethane responsibly, keeping it away from heat sources and ignition points. When unsure about specific properties or safe handling practices, consult the manufacturer’s instructions or a qualified professional.