Inside Info on Insulation
By James Dulley from January 2014 Issue
My house is chilly and I know it needs more insulation. Will adding more make me feel warmer as well as cut my utility bills? What's the best type of insulation to use for this and a new room addition?—Sandi H.
There really is not one "best" insulation to use in all locations in your house. You can save on energy with the right insulation—and feel more comfortable, too—if you match the type of product to the location in your house. Attic space and exterior walls present different opportunities to improve your insulation.
A chilly house can happen two ways. Conductive heat loss occurs when heat is transferred directly through materials such as drywall, studs, and bricks. Standard fiberglass batts, blown-in fiberglass, cellulose, rock wool, and foam can be used to block this kind of heat loss. Radiant heat gain occurs when the sun warms your house in the summer, but in the winter radiant heat loss occurs when your house gives up heat to the cold outdoor air and nighttime sky. Radiant barrier types of insulation, often an aluminum foil film, are effective for blocking this kind of heat transfer. Some standard insulation batts include a foil facing to reduce both types of heat loss.
If the amount of space available for the insulation is limited, as in a masonry wall, injected foam is a good option. The closed cell foam also creates its own vapor barrier and stops air leaks. Look for foam that uses no ozone layer-damaging foaming agents.
You might consider some environmentally friendly insulation types made with recycled materials. Some fiberglass manufacturers use 20 to 30 percent recycled glass in their products. Another effective insulation is made from scrap blue jean material that's formed into batts. It's treated for fire safety and can insulate about as well as fiberglass batts. Rock wool insulation is also made primarily from waste products.
Instead of batts, you might try another option known as the Blow-In Blanket System (BIBS) insulation for your room addition. First a special film is stapled up over the wall studs. Next, loose-fill insulation is blown into the wall cavity, then smoothed out through the film, then the drywall for the interior is nailed over it.
How to use the rating system
What is important when selecting insulation is its installed R-value, not just its thickness. A higher R-value is better. Some types of insulation have twice the R-value per inch thickness as others. But beware: although doubling the amount of insulation in an attic typically cuts heat loss through the room's ceiling by about half, doubling again will only reduce heat loss by another quarter.