Spray polyurethane foam (SPF) is a spray-applied plastic that can form a continuous insulation and air sealing barrier on walls, roofs, around corners, and on all contoured surfaces. It is made by mixing and reacting unique liquid components at the job site to create foam. The liquids react very quickly when mixed, expanding on contact to create foam that insulates, seals gaps, and can form moisture and vapor barriers. SPF insulation is known to resist heat transfer extremely well, and it offers a highly effective solution in reducing unwanted air infiltration through cracks, seams, and joints.

Types of Spray Polyurethane Foam

There are three primary types of SPF that can be used for insulation and other specific purposes:

High Density: often used for exterior and roofing applications
Medium Density: often used for continuous insulation, interior cavity fill, and unvented attic applications
Low Density: often used for interior cavity fill and unvented attic applications

Each product offers unique benefits that a professional SPF contractor can explain to you and help you determine which types of foam will be most appropriate for your building, climate, and project. Beyond the structure of the foam itself, the other significant difference relates to how it is created and installed.


Your SPF contractor can help you choose the appropriate product and delivery system for your renovation or insulation project.

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What is Spray Foam

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The R-Value Myth

R-value is a measure of resistance to heat flow, but it only measures resistance to conduction. Conduction (heat transfer through solid molecules) is only responsible for 20% of a building’s heat loss, while convection (heat transfer by air molecules moving from hot to cold areas) is responsible for the other 80%. Conventional fiber insulations resist heat loss by conduction, but only attempt to slow down convection currents by trapping dormant air molecules. The air is free to move within and through the insulation, which decreases the insulation value and can lead to damaging moisture problems. Spray foam insulations do not allow air to enter, which stops heat loss convection. 1/4” of foam will stop 99% of heat loss by convection, and 3” of foam will stop 95% of heat loss by conduction.

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