The Columbian | Serving Clark County, Washington

I live in an old home with no insulation in the walls. Would installing foam insulation be a good idea?

Adding insulation to an uninsulated wall will make a difference in your energy bills. Foam, like all insulation, can help stop the transfer of heat and cold between the outdoors and inside the house. Foam also can stop the movement of moisture from the inside of the house into the wall cavity, minimizing concerns about mold and mildew in walls.

“Another nice thing about foam is it insulates and air seals,” said Bob West, Clark Public Utilities energy counselor. “You get both in one product because it so completely fills the cavity. It will pay for itself if you have no insulation.”

Sealing a house stops air leaks which keeps warm, heated air inside in winter and hot outside air from entering in summer.

• What is foam insulation?

According to Josh Hancock, installation specialist with Spray on Foam in Brush Prairie, all blown foams are made using petroleum. However, manufacturers are introducing greener products with vegetable oil or soy to offset some of the product’s petroleum.

“But no product exists that replaces the petroleum totally,” Hancock said.

• Installation requires a pro

Installing foam insulation is not a do-it-yourself job. Professional installers use special equipment to blow the liquid into wall cavities.

On a retrofit project, they can install foam in walls from inside or outside the house. In an outside application, they remove a piece of siding, then drill small holes between the wall studs about 4 feet from the ground around the house perimeter. They then fill the cavity with foam until it reaches the hole.

“We pound a plug into the hole, replace the siding and then repeat the process, drilling holes near the top of the wall and filling the upper part of the cavity,” Hancock said. An inside application uses the same process.

• R-values save energy

Hancock said an old house with 2x4 walls would end up with an R-value of 17.8. An R-value is the measure of how well insulation stops air movement. The higher the R value, the better the insulation. A foam insulated 2x6 wall would have an R-value of 24.5.

Be prepared to pay more for foam insulation than fiberglass or cellulose.

“You may pay as much as double,” West said. “But you are adding the air sealing quality that cellulose or fiberglass won’t give you.”

Hancock said R-values drop if cellulose or fiberglass insulation compresses or gets damp. The quality of the installation makes a difference, too. To achieve promised R-values, fiberglass or cellulose must fit snugly into the cavity, without any air gaps.

“Homeowners can save 30 to 50 percent on their energy bills with foam insulation,” Hancock said. “We use it in attics, walls, crawl spaces, basement walls and foundations.”

The Energy Adviser is written by members of the energy counselor team of Clark Public Utilities, who provide conservation and energy use information to utility customers. Send questions to energyadviser@clarkpud.com or to Energy Adviser, c/o Clark Public Utilities, P.O. Box 8900, Vancouver, WA. 98668. A panel of local energy efficiency and energy product specialists will review your questions. Previous topics are available at http://www.clarkpublicutilities.com.

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