Spray foam under roof or spray polyurethane foam insulation, also known as pu foam insulation, also abbreviated as SPF (spray polyurethane foam). This material has been used in construction to reduce heat for many years. Polyurethane foam offers both open cell and closed cell insulation properties with low thermal conductivity coefficent. The foaming is produced by a high pressure spray process. When the two materials interact, the effect is white foam along the spray line. There are 2 types of foam as mentioned above.

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1. Open cell polyurethane foam, designed to contain large molecules and open the surface to be exposed to moisture in the air. Can exchange or allow air to circulate, no opacity, not waterproof For internal use only Cannot be used in waterproofing or waterproof works because of its water-absorbing properties. 

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2 closed cell polyurethrane foam It has a molecular nature that closes when ejected. It has a density of 30-60kg/m3f, which is the type used in Phraelan in Thailand and almost all of them are like this. The inside of the foam retains gas for better heat resistance.