What is foam glass?
Foam glass (cellular glass) is a rigid insulation material made by foaming recycled glass into a structure of millions of closed glass cells; it is vapour-tight, compression-resistant, non-combustible, waterproof and immune to vermin. Because of this combination of properties, foam glass is used in locations where ordinary insulation materials fall short, such as beneath loaded floors and foundations.
Construction
Foam glass is produced by mixing finely ground glass with a foaming agent (carbon) and heating it to a high temperature. The glass melts and expands into a rigid foam structure of closed cells, which is then sawn into boards or blocks. The closed cells contain no circulating air, so the material does not absorb moisture.
Properties
| Property | Foam glass |
|---|---|
| Vapour transport | vapour-tight (closed cell) |
| Compressive strength | high, dimensionally stable under load |
| Fire behaviour | non-combustible (class A1) |
| Water absorption | negligible, waterproof |
| Vermin/mould | immune, does not rot |
Application
Foam glass is used, among other places:
- Beneath foundations and floors, as a compression-resistant, moisture-immune insulation layer.
- On flat roofs, where vapour-tightness prevents condensation within the structure.
- In perimeter insulation, along below-grade walls and basement walls.
- In cold stores and freezer rooms and at thermal bridges.
Thanks to its compressive strength, foam glass can carry high loads without settling.
Related terms
- Cellular glass
- Perimeter insulation
- Vapour barrier
- Compression-resistant insulation
- Flat roof
- Thermal bridge
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