Why is Foam Glass Used in Boat Insulation?

The unique process and properties of cellular glass insulation (foam glass insulation) make it the go-to boat insulation material in many cases. This material is made from crushed recycled glass heated to high temperatures. Then, when combined with a foaming agent, it forms a rigid, lightweight structure filled with sealed glass cells. Though more commonly found in industrial and commercial marine settings, like shipyards and offshore platforms, it is gaining attention in high-performance or specialty boat builds for several compelling reasons. More on that below.

Boat insulation material is an often overlooked detail, but at Next Gen, we never overlook details. We pay attention to small details, so owners spend more time enjoying their watercraft. We have one of the largest inventories of boat insulation materials in the state, and our staff has the know-how that owners need as well.

Moisture Resistance

Foam glass is completely water resistant. That quality alone may make it one of the best marine insulation substances available. Once the glass cells are sealed, the material is completely non-porous, quite unlike open-cell foams or fibrous materials.

Sealing is a significant advantage in marine environments, where constant exposure to humidity, saltwater, and condensation can degrade traditional insulators over time. Foam glass maintains its insulation value regardless of moisture conditions, making it ideal for bilges, hull interiors, and below-deck applications.

Fire and Thermal Resistance

Foam glass does not burn, produce smoke, or emit toxic gases when exposed to fire or heat. This property makes it an excellent insulation material for areas near engines, exhaust systems, electrical components, or other areas where fire safety is a concern.

Foam glass’s thermal resistance is also stable over a wide range of temperatures, typically from -450°F to 900°F, a spectrum that far exceeds many traditional boat insulation materials. This thermal stability ensures consistent performance in both cold and hot maritime environments.

Long-Term Stability

Foam glass never shrinks, settles, or otherwise degrades over time. UV light, pests, mold, and most chemicals, including fuels and oils, do not affect foam glass, making it ideal for harsh marine conditions. Its rigid structure also enhances the boat’s mechanical strength, which is useful for supporting loads or when being used in structural insulation applications. Once installed, it typically requires little to no maintenance and can last for the life of the vessel.

Acoustic Insulation

Although it’s not as flexible as materials like Mass Loaded Vinyl or acoustic foam, foam glass’s dense, closed-cell composition effectively dampens sound. This quality significantly reduces engine noise and vibration, especially in bulkheads or mechanical compartments. It is often combined with other materials in a composite insulation system to improve both thermal and acoustic performance.

Eco-Friendly and Non-Toxic

Since foam glass is made primarily from recycled glass, it is considered an environmentally friendly insulation option. It contains no ozone-depleting chemicals, fibers, or harmful VOCs (volatile organic compounds), making it safe for indoor and enclosed marine spaces. It is also fully recyclable at the end of its lifecycle.

For more information about marine insulation and construction, contact us.