tion and air convection within cavities. It enhances comfort, reduces the size of heating and cooling system that is needed, prevents winter condensation, reduces noise, slows air leaks and water vapor transmission and improves fire resistance. Dense-pack Cellulose The newest and most cost effective insulation is dense-pack cellulose. It is made from recycled newspaper with fire retardant coating. It is blown-into the wall and ceiling cavities with a compressor. Because it is packed tightly into the cavity it has a very high R-value of about R-3.6 to 3.8 per inch. It is so densely packed that it allows no air to flow through. It is both a thermal and an air barrier. It is the preferred insulation for walls and ceilings. It should not be used in wet areas such as crawl spaces and basements. Foam There are two types of foam insulation: High-density, closed cell- about R-7 per inch, and Low density, open cell- about R-3.5 per inch. Foam has excellent air sealing characteristics. It also offers excellent “fit”, since it expands to fill spaces and glues itself to surfaces. Therefore foam serves as both an air and thermal barrier. Foam also comes in rigid faced and unfaced boards. Foam is the best way to seal the band joist and sill plate in a crawl space or basement. It is also recommended to seal the basement walls down to below the frost line. The downside to foam is it is not fire retardant, and fireproof paint or foil facing must be applied to the foam on the basement walls. Attics—Air Seal First, then Insulate If the attic hatch is located above a conditioned space be sure it is insulated, weatherstripped, and closes tightly. It is an easily accessible major hole in the barriers. In the attic be sure openings for pipes, ductwork, and chimneys are sealed. Look for stains on 36 National Oilheat Research Alliance Figure 9 Sealing Band Joist and Sill Plate the insulation to locate leaks. Air leaks carry dust and dirt from the house with them. If the edges of the fiberglass are stained a dark color it means air is leaking there, these are often referred to as ghost stains. If there is no floor in the attic and the air leaks have been sealed it is easy to add more insulation: either loose fill or unfaced fiberglass batts. A foot (R38) of fiberglass or cellulose insulation is cost-effective in the attic floor. It is critical to install fiberglass batts properly. If there is a lot of ductwork, or if there are air handlers for hydro-air systems in the attic, the best attic strategy might be to bring the attic indoors, that is, instead of insulating the attic floor and ventilating the space, insulate the attic roof. Alternatively, if it will be difficult to seal the ducts and air handlers properly, the air and thermal barriers can be installed over the top of the ducts and air handlers so they are beneath the insulation instead of outside of it. Basements The sill plate, the rim joist, and the foundation above frost line should be sealed and
NORA Advanced Efficiency
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