Keeping your house warm without raising your heating bill

How to Insulate an Attic for Winter

by Benjamin Roussey

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Insulating the attic is one of the most effective ways to keep your home warm during the winter months and cooler in the summer. You will not only make your home more comfortable, but you will also be saving a lot on energy bills. Here are some important tips to help you effectively insulate your attic for the winter.

Selecting the Right Insulating Material

Insulating materials have an R-value, which is the material's resistance to heat flow. The insulation is more effective with a higher R-value. Secondly, insulation materials have a cumulative effect on the R-value. For instance, if you install two layers of R-15 insulating material, the total value of insulation will be R-30.

There are two typical types of insulation for an attic: blanket insulation and loose-fill insulation. Blanket insulation comes in rolls, and the material is comprised of fiberglass and a combination of the other fibers such as cotton, mineral wool, and plastic. Blanket insulation is available in different lengths and widths, making installation quite easy. On the other hand, loose-fill insulation can be installed only with special equipment handled by professionals. This insulation, comprised of clumps of materials like mineral wool, cellulose and fiberglass, is sprayed into the cavities of the attic wall and floor. It is also more expensive.

The recommended insulating R-value for Northeast, Northwest, Southwest, and Midwest of United States is R-49. For the California, Florida, Hawaii, Texas, and Louisiana coastlines the recommended R-value is R-38.


Before installing insulation, prepare your attic to make your work easier and safer. If there are no lights, then first you should install some temporary lighting. Then lay boards wherever required across joists to make walkways and hold the materials and tools.

Sealing Air Leaks

Before proceeding with installation of insulation, it is very important to seal all the air leaks in your attic. The usual areas where air leaks are possible include attic access panels, pull-down stairs, exhaust fan housing, recessed lighting, plumbing stacks, chimneys, and around interior partitions.

Use rigid boards for insulating access panels, and for the attic door, add a door sweep and weather strip. For pull-down stairs, use an airtight cover with insulation. Insulating around recessed lights can be tricky, as you need to keep the insulation away by three inches to avoid fire hazard. However, fixtures with IC (Insulation Contact) rating do not have this drawback. It is best to replace recessed lights with ceiling mounted or airtight fixtures. The collar around metal chimneys is usually loose and has to be repaired with a fire-rated sealant. For gaps on the top of interior walls, use caulk, and for plumbing stack vents, use expanding foam sealant.


Ventilation in the attic is as important as sealing air leaks. When installing insulation, make sure the ventilation is not blocked off. Ventilation should be planned to balance the exhaust and intake openings. About 50% of the venting should be used for drawing in air through soffits. It is better to have ventilation chutes, since they allow proper insulation to be installed at the edges. Proper ventilation in the attic will help prevent moisture build-up. If there is buildup of moisture, it will not only ruin the insulation but also cause various health issues in the home. Plus, outstanding ventilation will prevent the formation of ice dams. These formations can drive water below the shingles, which will damage walls and the roof.

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Benjamin Roussey is from Sacramento, CA, and grew up doing all varieties of home improvement projects around the home since his parents did not hire contractors or outside help to maintain their home or vehicles. As a result, he has acquired a multitude of home handyman skills in plumbing, carpentry, electrical and everything in between. He also has two Masters degrees and he served four years in the U.S. Navy.

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