How to Insulate My Roof

Installing insulation under your roof in your attic can help you reduce your heating and cooling bills.

Determining How Much Insulation You Need

Fiberglass insulation makes your roof and attic more energy-efficient.Fiberglass insulation makes your roof and attic more energy-efficient.
Attics are one of the easiest places in your house to insulate. Fiberglass insulation is the most widely used type of insulation. Take precautions when working with fiberglass; it will make you itch if it touches your skin. Always wear a dust mask, protective eyewear, work gloves, long sleeves and long pants when installing fiberglass insulation.

Measure the space between each joist in your attic with a tape measure.

Measure the length and width of the attic and multiply these numbers to calculate the attic's square footage.

Multiply the square footage of the attic by .90 if your joists are spaced 16 inches apart, and by .94 if they are spaced 24 inches apart. These numbers will indicate the square footage of insulation you'll need to cover your attic floor.

Installing Insulation

Place the insulation on the floor of the attic with the vapor barrier side down and the fiberglass up.

Lay the insulation in sections, beginning at each side of your attic and moving toward the center. Make sure the pieces fit snugly together and that they don't block any vents.

Cut scraps of insulation with the utility knife to piece the final sections together as needed.

Things You Will Need

  • Fiberglass insulation batting with vapor barrier
  • Tape measure
  • Utility knife

About the Author

JIm Cooper is an attorney and business consultant. He serves on the board of many corporations. He is also a published writer with more than 30 years of experience. Cooper's articles have been published in "American Executive," "Men's Health" magazine, "Newsweek," "Marie Claire" and "Mademoiselle" magazines.