Upper Michigan enjoys mild summer temperatures. But even on a day when it hardly tops 80, your attic may be an oven. Attics can easily run 40 degrees hotter than outside temperatures. Without sufficient attic insulation, this heat is conducted through the ceiling and into your living spaces, counteracting your air conditioner. Thermal transfer of heat from the attic is responsible for more than 30 percent of cooling costs during summer. Attic insulation — the right kind and the correct amount — is your first line of defense.
Insulation’s ability to resist heat flow is expressed as it’s R-rating. The R-rating of attic insulation is determined by its type and depth in inches. For upper Michigan’s climate zone, the Environmental Protection Agency’s recommended range is R-38 to R-49, which correlates with a minimum of 10 inches of cellulose or 15 inches of fiberglass. Insulation options in the attic are more varied than elsewhere. For example, one type of insulation may be added on top of a different existing type.
Types of attic insulation:
- Available in batts (blankets presized to fit between attic ceiling joists) fiberglass insulation’s main advantage is ease of installation. Its glass fibers don’t absorb water vapor that accumulates in attics, so it’s suitable for humid climates. Fiberglass has less mass than other types and doesn’t settle and stress the ceiling underneath. Attic insulation add-ons with fiberglass are most suitable for do-it-yourselfers.
- Cellulose insulation is made of ground-up paper or fabric treated with fire-retardant. It has an R-value per inch of 3.8 versus 3.2 for fiberglass batts. Cellulose also retards airflow better and its insulating properties aren’t affected by acutely high or low temperatures. Cellulose is a loose-fill insulation and must be blown into the attic space using special equipment. This adds superior coverage properties because it can be blown into many areas of the attic inaccessible to fiberglass batts. Cellulose is usually slightly less expensive than fiberglass.
Team Bob’s Heating Cooling Plumbing is your local contact for interior comfort in Grand Traverse County. Let us show you how we’ve established a 30-year track record of quality and trusted service.
Our goal is to help educate our customers about energy and home comfort issues (specific to HVAC systems). For more information about attic insulation and other HVAC topics, download our free Home Comfort Resource guide.