Are Your Insulation Materials Fire-Resistant?

Proper insulation reduces fire risk.

In 2022, the number of onboard fires hit a 10-year high. Faulty wiring may be the most common cause of marine fires. That is especially true in Florida. Year-round boat use often strains onboard systems, such as electrical wiring. Other causes include overheated engines or motors, fuel leaks, and galley fires that begin during cooking.

Fires are not only one of the most common onboard disasters. They are one of the most destructive ones. The flames are bad enough. Smoke and chemicals or water used to put out the fire often cause more damage than the flames. Proper marine insulation significantly reduces the risk of electrical and engine room fires. At Next Gen, we have the inventory and know-how to protect you and your passengers from onboard fires.

Common Types of Fire-Resistant Marine Insulation

Fire-resistant insulation withstands high temperatures and keeps small fires from becoming big ones. Government inspectors usually rate different kinds of marine insulation based on their performance in fire-related tests, such as flame spread and smoke development. Most boaters want a down-the-middle kind of insulation. They usually don’t need maximum protection, but they do not want the cheap stuff either.

Fiberglass insulation, which is made from fine glass fibers, is one of the lightest, easiest to install, and most fire-resistant insulation materials available. Most fiberglass is non-combustible, so it will not burn. This insulation withstands temperatures up to 1,000°F or higher and does not require additional fire retardant chemicals. However, beware that cheap fiberglass batts are often backed with paper or foil, which can be flammable. Always check the product label to ensure it meets fire safety codes. Don’t simply assume “fiberglass” insulation is fireproof.

Mineral wool (a/k/a rock wool or slag wool) insulation is another excellent fire-resistant option. It is made from natural rock or industrial slag and formed into fibers. Like fiberglass, it is non-combustible and can resist temperatures over 1,800°F. Because of its high melting point and low flame spread, mineral wool is often used in fire-rated wall assemblies and around mechanical systems.

Recycled paper-based cellulose insulation is treated with fire-retardant chemicals, like borates, to improve fire resistance. While it is not naturally fireproof, the chemical treatment allows it to meet most building code requirements. However, over time, the effectiveness of these fire retardants can diminish, and if cellulose becomes wet or settles, its fire resistance may be compromised. Therefore, cellulose often isn’t a good choice for marine vessels that vibrate constantly.

Spray foam (both open-cell and closed-cell types) is made from polyurethane or similar materials. All forms of spray foam are combustible and release toxic fumes when burned. For this reason, spray foam must be covered with a thermal barrier, such as drywall, in common areas. Manufacturers may add fire retardants to meet code, but they should never be left exposed in occupied areas.

Rigid foam insulation, including EPS, XPS, and polyisocyanurate, varies in fire resistance. Most are combustible and must be used with a fire barrier. Polyisocyanurate tends to have better fire performance due to its higher ignition temperature, but it is still not non-combustible.

For more information about marine insulation and construction, contact us by going online or calling 954-789-3665.