Spray Polyurethane Foam (SPF) Insulation

For large to mid scale applications, a two component mixture comes together at the tip of a gun, and forms an expanding foam that is sprayed onto concrete slabs, into wall cavities of an unfinished wall, against the interior side of sheathing, or through holes drilled in sheathing or drywall into the wall cavity of a finished wall.

Advantages

• Blocks airflow by expanding and sealing off leaks, gaps and penetrations.
• Can serve as a vapor barrier with a better permeability rating than plastic sheeting vapor barriers and consequently reduce the build up of moisture, which can cause mold growth.
• Can fill wall cavities in finished walls without tearing the walls apart (as required with batts).
• Works well in tight spaces (like loose-fill, but superior).
• Provides acoustical insulation (like loose-fill, but superior).
• Expands while curing, filling bypasses, and providing excellent resistance to air infiltration (unlike batts and blankets, which can leave bypasses and air pockets, and superior to some types of loose-fill. Wet-spray cellulose is comparable.).
• Increases structural stability (unlike loose-fill, similar to wet-spray cellulose).
• Can be used in places where loose-fill cannot, such as between joists and rafters. When used between rafters, the spray foam can cover up the nails protruding from the underside of the sheathing, protecting your head.
• Can be applied in small quantities.
• Cementitious foam is fireproof.

Disadvantages

• The cost can be high compared to traditional insulation.
• Most of all, with the exception of cementitious foams, release toxic fumes when they burn.
• Depending on usage and building codes, most foams require protection with a thermal barrier such as drywall on the interior of a house. For example a 15-minute fire rating may be required.
• Can shrink slightly while curing if not applied on a substrate heated to manufacturer's recommended temperature.
• Although CFCs are no longer used, many use HCFCs or HFCs as blowing agents. Both are potent greenhouse gases, and HCFCs have some ozone depletion potential.
• Most, such as Polyurethane and Isocyanate insulation, contain hazardous chemicals such as benzene and toluene. These are a potential hazard and environmental concern during raw material production, transport, manufacture, and installation.
• Many foam insulations are made from petrochemicals and may be a concern for those seeking to reduce the use of fossil fuels and oil. However, some foams are becoming available that are made from renewable or recycled sources.
• R-value will diminish slightly with age, though the degradation of R-value stops once an equilibrium with the environment is reached. Even after this process, the stabilized R-value is very high.
• Most foams require protection from sunlight and solvents.
• It is difficult to retrofit some foams to an existing building structure because of the chemicals and processes involved.
• If one does not wear a protective mask or goggles, it is possible to temporarily impair one's vision. (2-5 days)