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Energy Efficiency

Making Your Home Cozier

Add attic insulation to cut energy costs by up to 50%

As the season changes to cooler weather, your thoughts also might turn to keeping out the coming winter cold. Insulating the attic is an effective way to help keep your house cozy and energy efficient—not just over the cool months but at all times of the year.

The U.S. Department of Energy estimates homeowners could reduce energy costs by 10%­–50% with proper attic insulation.

Typically, houses in warm-weather states should have R-38 insulation in the attic, whereas houses in cold climates should have R-49. Check with your local building department for code requirements.

If you discover you need more insulation, you might be worried about the process, especially if your home already has some insulation. Rest assured that in most cases, you can add the new insulation on top of old insulation.

An exception to this is if the existing insulation is or has been wet. Wet insulation can promote the growth of mold or mildew and cause building materials to rot. If it’s wet or appears to have water damage, you should look for the cause and repair the problem to prevent it from happening again. Then remove any wet or damaged insulation.

Here are some additional considerations for adding insulation to an attic:

  • Batt or rolled insulation and blown loose-fill insulation (made of fiberglass or cellulose) can be installed on top of old insulation.
  • Do not place “faced” insulation on top of existing insulation. Any new batt or roll of insulation added on top of existing insulation in the attic needs to be without a vapor retardant, or facing, because this paper between layers of insulation can trap moisture. Any existing batt or roll insulation should place the facing against an attic’s drywall floor—or have no facing at all.
  • If you cannot find unfaced rolls of insulation, you can carefully pull the kraft paper off without much loss of insulation.
  • If your new insulation is in rolls, you should roll it out perpendicular to the joists. Be sure to use unfaced rolls or pull off the kraft paper.
  • You should not tack down rolled insulation. Insulation needs to be fluffy to block heat flow. Squashing insulation flat to tack it down will reduce the R-value, or effectiveness.
  • If you discover vermiculite insulation in your attic, be sure to have it tested before doing work there because it might contain asbestos. If the test reveals that asbestos is present, a certified removal expert should remove the vermiculite.
  • You also can hire a contractor to blow loose-fill insulation in your attic.
  • If tackling the project yourself, be sure to take safety precautions, including wearing a long-sleeve shirt, gloves, eye protection and a dust mask. Take care not to cover can lights unless they are rated for contact with insulation. And be careful not to step through the ceiling!
  • Remember, a tightly sealed house is as important as insulation, so fill all cracks in the living area and the attic with caulk or expanding foam. Some areas to pay special attention to are around attic windows, pipes, wires, exhaust fans and ducts, and chimneys and flues.