abbr. open-cell spray polyurethane foam

A type of spray foam insulation with a semi-rigid cellular structure and a density between 8 and 22 kg.m3 (0.4 and 1.4 lb/ft3). Provides a nominal thermal resistance of R-3.6 per inch (this will vary from manufacturer-to-manufacturer). Some spray foams use greenhouse gases, but others, such as water blown foams, do not.