In part one of this series on attic insulation, you will learn how to evaluate your attic and decide if you need new insulation and, if so, what kind and how much of it.
Do I Have Enough?
No matter what kind of insulation you currently have in your attic, one quick way to determine if you need more is to look across the span of your attic. If your insulation is just level with or below your floor joists (i.e., you can easily see your joists), you should add more. If you cannot see any of the floor joists because the insulation is well above them, you probably have enough, and adding more may not be cost effective. It is important that the insulation be evenly distributed with no low spots—sometimes there is enough insulation in the middle of the attic and very little along the eaves. If your attic insulation covers your joists and is distributed evenly, you probably have enough.
How Much Should I Add?
Insulation levels are specified by R-Value. R-Value is a measure of insulation's ability to resist heat flow traveling through it. The higher the R-Value, the better the thermal performance of the insulation. The recommended level varies by region and insulation type.
Add the Right Kind of Insulation
When adding insulation, you do not have to use the same type of insulation that is already in your attic. You can add loose-fill on top of fiberglass batts or blankets and vice versa. If you use fiberglass over loose-fill, make sure the fiberglass batt has no paper or foil backing—it needs to be "unfaced." If you choose to add loose fill, it may be wise to hire a professional, as the application requires the use of a blowing machine. You can rent this machine, though, if you're dead set on a DIY approach.