Expanding spray foam insulation is made of polyurethane or acrylic latex. The foam has been used in refrigerators and water heaters for many years.

Liquid polyurethane is pressurized and released through spray nozzles. When the spray lands on surfaces it expands and foams up, then hardens to a aerated material. Traditional insulation such as cellulose wool or spun fiberglass leave gaps and voids when applied as ceiling and wall insulation. Expanding spray foam insulation fills out to all cracks and into seams even if they are hidden from view. The sealing ability can practically eliminate air flow and energy transfer.

The resulting expanded polyurethane foam has a high R-value, which is the measure of resistance to energy flow relative to its thickness, when compared to other insulation materials. This high R-value feature can allow 4″ wall construction to achieve the same energy rating as a 6″ wall, providing improved performance at a substantial savings in construction materials and even increased floor area.

Because expanding spray foam insulation is dimensionally stable it does not settle or compress, and maintains its high performance characteristics. It does not absorb or transfer moisture, preventing humidity, condensation, and mold problems. It is also insect and flame resistant.

Although there are retail products for small crack filling tasks, expanding spray foam insulation for large areas is best left to professionally trained contractors who have the necessary equipment and expertise to apply this material effectively and economically.

There are hazardous materials handling issues when the polyurethane is in the liquid and aerosol state that require special precautions. Proper application and cavity filling requires experience and care to achieve the desired outcome and prevent damage or distortion of structural elements by over-expansion.

Coordination with plumbing and electrical installation is critical since the foam insulation encloses these utilities and makes it difficult to change or reinstall.

Expanding foam insulation costs about three times more than traditional materials to install initially. Some of this cost will be offset by savings in other areas and materials as mentioned above. However the longterm payback is increased energy savings year after year, with improved comfort and air quality, that justifies the investment in using expanding spray foam insulation.

There are many benefits to this form of insulation over traditional materials. These benefits include ease of installation and durability.

Ease of Installation
The chemical resin can be sprayed in liquid form onto the desired area without measuring, cutting, or fasteners. It adheres to practically everything used in typical house construction such as concrete, masonry, wood, and metal. Application is fast and simple.

Durability
Expanding foam insulation lasts longer than previously used materials. It maintains its effectiveness longer with resistance to breakdown, compression, moisture absorption, or attack by critters.

Since it is unaffected by moisture it also is practically impervious to mold even in damp areas. Because it is inorganic it is not attractive to animals and insects for eating, gnawing, or nesting.

The inorganic compounds are non-polluting and benign to the environment. The effectiveness of using expanding foam insulation improves the air quality of your enclosed spaces by preventing infiltration of exterior pollutants from entering.

The biggest benefit of using expanding foam for insulation and sealing is the reduction of energy transfer. Thermal resistance reduces conductivity, and sealing gaps and cracks reduces air convection. Overall energy savings are considerable and make it cost effective to use expanding foam insulation.

The contemporary best practice is expanding spray foam insulation installation. Foam fills the cavities in between the framing studs of the walls and attic. Spray-on foam expands to fills in air gaps, unlike standard fiberglass insulation, which lets air pass through and around it. Even as a house expands and contracts the foam insulation expands and compresses with it. This prevents warm air from escaping through cracks and spaces.

A professional installer has the equipment to cover large areas quickly so that it is more cost effective than doing it yourself, but for small areas and sealing cracks you may choose to do it yourself. For a large space being installed with expanding spray foam insulation, the liquid to sprayed evenly between studs on the inside of the exterior sheathing. The material quickly expands 100 times its volume to fill all the gaps in the stud wall or rafter space. After the foam has set a handsaw is used to smooth off the excess from the framing. The wall or ceiling is now ready for drywall installation.

A better air-tight envelope is achieved by using expanding spray foam insulation in the walls and attic. The foam is non-toxic, high R-value, moisture-proof, fire resistant, and sound damping.