Putting A Lid On Heating Costs

Installing attic insulation

Because warm air naturally rises, the attic or roof area of your home is your first priority for insulating. Insulation reduces the upward flow of heat, keeping it inside your home longer. That means you'll stay warmer, and your heating system will not come on as often—reducing your
utility costs! In Montana's cold climate, insulating existing attics to an R-value of at least .38 is recommended. R-value is the measure of an insulation material's ability to resist heat flow. It's measured per inch of material. For example, glass fiber batt or blanket insulation has an R-value of around 3.2 per inch, and the R-value of loose-fill cellulose is about 3.7 per inch. Both of these insulation types are commonly used to insulate attics. Twelve inches of the glass fiber batt insulation achieves R-38, and about 10 1/2 inches of cellulose will do the trick. How much insulation is in your attic?

Attic/Roof Types
How your attic should be insulated depends on how your roof is built. Common attic/roof types are:

1. Unfinished Attic. In these homes, the attic is not part of the living space. You can often get into the attic by ladder through a hatch usually located in a hallway or closet ceiling. Unfinished attics are generally the easiest type to insulate; the insulation goes between the framing members (joists) of the attic floor, which is also your living area's ceiling. Capable do-it-yourselfers can tackle this job with advice from a professional. Rolls of glass fiber or loose-fill cellulose have been the insulation of choice for most do-it-yourself jobs. This brochure primarily deals with steps you can take to add insulation to your unfinished attic.

2. Finished Attic. A portion of these attics are living spaces. As a result, insulation should be placed in the exterior walls (called kneewalls), the entire ceiling and the outer floor areas—those
not part of the living space. An experienced professional should be called upon for this job since it often requires the use of several insulation products and use of special insulation blowing equipment.

3. Flat, Vaulted or Cathedral Ceilings. These types of ceilings don't have attics above them, and due to little or no space to add insulation, it may be impossible to add insulation to this
roof type. If there is space, the insulation must be blown or placed between the interior ceiling and the exterior roof. It's very important that these construction types be well-ventilated and sealed to prevent moisture problems. They, too, usually require the expertise of a contractor.