Foamed insulation is a bit expensive initially, but lasts longer and insulates better than others. It is made of various materials in their liquid states, and can be sprayed, injected or poured into the building envelope. Because foamed insulation can be made of many different materials, its R-values vary widely, from around 3 to at least 8.

Its main advantage is that, after application, it expands throughout the building cavity to fill the entire space completely, then “cures” (partially solidifies) to its final state. This effectively seals the interior of the building, ensuring that the full R-value of the insulation is realized. This is something that cellulose and fiberglass cannot do. (Link to article on the difference between insulation and sealant.) Because it can be sprayed into existing wall cavities, foamed insulation is a good option for houses that are already fully constructed.

Special equipment and training are required for the installation of foamed insulation. Foam insulation is seen as more susceptible to insect and rodent burrowing. Some types of foamed insulation, including polyurethane and polyisocyanurate, often use chlorofluorocarbons or hydrochlorofluorocarbons to reduce heat conductivity. CFCs and HCFCs are known to deplete the ozone layer and to contribute to global warming. If you choose to use foamed insulation, please ask your contractor to avoid using a type that contains these gases.

For more information on foamed insulation, please visit:

EERE Consumer’s Guide: Sprayed-Foam and Foamed-In-Place Insulation

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