Insulation in the roof and walls is clearly beneficial for its ability to reduce heating and cooling losses and costs. The savings achieved by reducing heat transfer by conduction justifies the cost of adequate insulation.

But don’t forget that convection is another source of heat transfer when air moves between two spaces. Minimizing or controlling losses via convection is desirable but requires more consideration. Adequate outside air is necessary for breathing, and sufficient air transfer is required to ventilate other gases and odors from interior spaces.

Most homes are so leaky that there is plenty of opportunity for air to intrude and be enough for the occupants. However, as structures become more air-tight and interior materials become more synthetic, there is the possibility that the indoor air quality is compromised.

Controlling infiltration of outside air is important. Not only is uncontrolled air infiltration wasteful of energy it can also carry outside pollutants such as fumes and dust. Inadequate exhaust of indoor pollutants can cause allergies, respiratory distress and ‘sick building syndrome’.

Expanding foam insulation applied to walls and roof voids fills small spaces and gaps that allow air to flow between the interior of a home and the outside environment. Eliminating these gaps prevents air convection from carrying heat between the interior and exterior of a home, which results in lowering the expense of heating or cooling a space.

Minimizing air from entering from the outside into the house means that expanding foam insulation can improve the quality of air inside your house. With proper permeable filters and especially electrostatic filters installed with your air-handler, circulating inside air can be controlled and cleaned of allergens, particulates and pollutants within a building’s interior. By using expanding foam insulation to reduce infiltration of outside contaminates, the inside air is a higher quality. This may be an even more important consideration if a resident suffers from allergies or respiratory conditions.

A more sophisticated installation that is used in commercial buildings and may be justifiable in homes is the use of an ‘economizer’ air handling system. By using an arrangement of ducts and dampers in an ‘H’ pattern outside air and exhaust air can be controlled to allow recirculation and proper ventilation. Depending on the sensible heat and latent heat outside, controllers move the dampers to allow the desired air flow in and out of the building space, which maintains adequate fresh air and takes advantage of the energy of the exterior for cooling or heating. This is especially effective for ‘air-tight’ structures and locations where day and night time temperatures and humidity vary significantly.

Expanding foam insulation is extremely useful to address multiple issues of conduction and convection. Whether it is maintaining the temperature of a home, controlling air infiltration, soundproofing a space, and minimizing energy consumption, almost everyone will enjoy the benefits of expanding foam insulation.

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.