With our wet Northwest winters, the soil under concrete slabs becomes saturated and soft, or washes out completely. Polyurethane foam — available from dealers as PolyLevel — can be a solution ...

The foam does not degrade under the slab so there is no need to worry about contamination of soil or groundwater with dangerous compounds. Polyurethane foam is strong and permanent.

Forming concrete. That’s according to a team at ETH Zurich who claims that construction with foam forms cuts concrete usage up to 70%. It also offers improved insulation properties.