Foamglas

Foam glass is a cellular glass insulation made from post-consumer recycled glass.

I am interested in using it under the patio, ground floor and basement slabs and as the tanking/insulation for the basement. When calculating the insulative U-Value of Foamglas vs. polyurethane insulation, Foamglas works out at about 1.9 times the price but it has some unique properties which distinguish it from other insulations. The key advantages being-

Foamglas sample - looks like sponge but is hard and solid and can support 160 tonnes per square meter.

Patio Slab - Possible Idea

The Toblerhome's patio area is above the bedroom. For various reasons (which I'll write about later) I would like the floor of the patio to be a solid slab of lime supported on timber i-beams. Lime (and concrete to a lesser extent) are porous materials with negligible insulation properties. The typical way of waterproofing this kind of construction is to use felt and bitumen to seal the surface and polyurethane boards in the ceiling. The problem with bitumen felt roofs is that over the years, they split. This in turn is minimised by building roofs with a high thermal mass. Slowing the warming and cooling reduce the effect.

The alternative idea is to board on top of the timber i-beams to achieve a flat surface for the Foamglas. Use enough Foamglas to eliminate the possibility of interstitial condensation (dew point being within the building) and to support a slab of lime. The lime will be finished with slate to match my roof and make it hard wearing.

As with any other patio, most of the water will drain to the lowest point. Any water absorbed into the lime will be wicked around the lime to aid evaporation or to the lowest point where it will drain.

I don't yet have approval for my alternative idea but if you know anything about construction, please contact me and let me know what you think.

The manufacturer's UK website contains loads more info.