Spray foam insulation has been used to stop heat escaping from roofs, lofts and attics for decades and comes in two forms. Closed cell spray foam is rigid once set. It is a better thermal ...

In his guide, he details the difference between XPS (expanded polystyrene) and EPS (extruded polystyrene) and how each product’s closed cell and open cell nature affects the final board.

Foam board insulation Foam board insulation ... expanding to fit into every small gap to minimize heat loss and gain. With closed cell insulation firming up as it sets, it can reduce ventilation ...