To make houses, polystyrene foam is sandwiched between two slabs of steel wire mesh. Once these have been joined together, they are sprayed with cement to support and strengthen the walls.

Polystyrene foam is still being sold in the state of California despite a ban that went into effect on Jan. 1, 2025. (Susanne Rust/Los Angeles Times) Same with the restaurant supply shop KaTom ...

ACH Foam Technologies' Foam-Control MAX graphite polystyrene (GPS) is a rigid foam insulation well-suited for vertical construction applications where a high performance building envelop is desired.