Networx: Insulation ratings: What they mean for your home
Often, though, homeowners simply don’t know enough about insulation: Where to install it and which type is best. That’s why we’re presenting a primer on insulation ratings of common materials, and the best locations to install them in your home.
R-Value: Measuring insulation ratings
Insulation ratings comparison (per inch)
There are numerous home insulation materials available. To compare their insulating ability, look at each one’s R-value per inch of thickness. However, note that R-values do not necessarily increase in direct proportion to increases in thickness, due to compaction. Insulation ratings also tend to change over time, with improvements in materials.
— Batts and blankets made out of fiberglass or rock wool provide an R-value of 3.1-4.0.
— Blown-in loose fill made of cellulose, fiberglass, or rock wool fibers or pellets has an R-value of 2.4-4.0.
— Rigid foam (extruded polystyrene, expanded polystyrene, polyurethane, polyisocyanrate) has an R-value of 3.5-7.5.
— Spray foam manufactured from polyurethane or polyicynene offers an R-value of 3.6-7.0.
— Radiant barrier of reflective material (generally aluminum foil is used as attic insulation, mainly in warm regions to reduce heat gain and cooling costs. It is not usually rated for R-value.
Best home locations to insulate
Floor of unfinished attic. In an unfinished attic, insulate the floor to form a barrier which will minimize cold air (or hot, in summer) getting into your living space below. Don’t forget the insulation for the attic access door.
Finished attic walls and ceiling. If you use your attic as a bedroom, home office, etc., apply insulation to the ceiling, between the studs of interior knee walls, and outside between the studs and rafters of the walls and roof.
Floors atop cold areas. Similarly, insulate your floor above an unfinished cellar or crawl space. Ditto for any living quarters over your unheated garage.
DIY home insulation tips
— Check your local building code to find out where and how much insulation is required.
— To keep out moisture, look for insulation materials equipped with a vapor barrier.
— Remember to minimize air leakage by weatherstripping around doors and windows, installing thermal drapes, and plug cracks or gaps with caulk. Consider dry walling over an exceptionally cold wall to add a layer of protection.