Rosie on the House: What is foams role in a house?

Youve probably already heard of foam used to cover flat roofs found on many of Arizonas pueblo-style homes. Its roofing that keeps out rain but also reflects heat. Foam also plays a big role in insulating many newly built homes. Its role is growing in improving the quality of life inside older homes as well.

Foam insulation is generally a polyurethane product and much of it is sprayed on surfaces or injected into walls. Besides insulating, the foam can serve as a vapor barrier, protect against noise, deflect water and resist mold.

Here are some of its uses:

--Foam in exterior walls Do you live in an older, concrete block masonry home? These masonry homes are probably the best kind of construction for Arizona because of their structural strength and their resistance to fire and termite damage. Many tens of thousands of these homes were built in this state during the 1950s and 60s. Sometimes these homes were built from slump block or from concrete blocks finished with brick or stucco facing. If you have one of these older homes, you know they usually have one big problem. Many had no effective insulation put in their walls.

But since the 1990s, foam insulation has become a popular way to fix this problem. For the injection process, workers make small holes on the outside of the house that can be easily repaired later. The foam is injected via a hose into the cores of concrete-block or masonry walls in the home. As the foam enters the walls, it fills all the empty cells in the blocks, including the joints between blocks. Not only will this material help reduce utility bills, it will also help keep out insects and dust. Your home will also be much quieter.

Its estimated that the foam can increase the R-value of these masonry walls several times. R-value, of course, is a measure of the thermal resistance to heat flow; the higher the number the better the insulation.

The average-sized masonry home can be done in half a day; cost varies depending on the homes size.

Some retrofitting companies say frame construction homes, the most common type of housing in Arizona, can also benefit from having foam injected into walls. But our view is that if your wood-frame home is not too old and has good existing insulation, foam injection may not be that helpful. Even if it works slightly, it may cost you more than you will gain in lower energy bills.

Before retrofitting the walls of your home, have a whole house energy audit done first to find out how effective your current insulation is.

--Foam in interior walls Foam can be used as well in interior walls in any type of home whether masonry or frame construction -- to help reduce noise. For example, if a bedroom in your house is next to the utility room, it can be tough to sleep when the clothes washer is running. Injecting foam in that wall will make the bedroom much quieter.

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Rosie on the House: What is foams role in a house?