A strong yet light insulator, foamed glass is suitable for load bearing applications especially those demanding water and vapour resistance.
Foamed glass insulation is made from (usually) recycled glass that is mixed with carbon and then heated to very high temperatures. Upon heating the carbon oxidises and forms bubbles in the resultant stone-like material. It is usually supplied as a gravel, but is also available in (very expensive) batts.
- High embodied energy. In the glass from which it is produced.
- Renewable . In that it is produced from recycled glass.
- Durable, hard-wearing and able to bear weight. Suitable for roofing in high-load situations such as structural walls, above ground level car parks and green roofs. Ty Mawr lime use it as an insulating moisture barrier in their limecrete floors
- Water and vapour impermeable..
Typically in the range 0.037 – 0.048 W/m.K. (Watts per meter Kelvin ~ a lower value is a better result)
With strength comes cost …for gravel at a depth of 100mm, cost is around £15 per square metre or around £150 for a cubic metre bag.