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After you complete air sealing, consider whether you need to add insulation. Insulation is essential for reducing heat flow through a home’s building envelope (the parts of the home that separate the interior from the outside elements, including the walls, roof, and foundation). The greater the difference between the indoor and the outdoor temperatures, the more energy it will take to maintain a comfortable temperature in your home.

Adding insulation between the indoors and the outdoors reduces that energy demand, improves the comfort of your home, and saves you money.


An insulation’s R-value is a measure of its resistance to heat ow; the higher the R-value, the greater the insulating effectiveness. R-value is dependent on the type of insulation and the thickness. When purchasing insulation, refer to the insulation packaging or the paper backing of rolled insulation to find the R-value.

How Much Insulation?

Consult the ENERGY STAR® recommended insulation levels for retrofitting existing wood-framed buildings to determine how much insulation you should consider adding to your home. For masonry sidewalls (such as concrete block or poured concrete), it is sometimes feasible to install rigid insulation on the outdoor side. However, if that is not an option, you can use rigid insulation boards or batts to insulate the interior of masonry walls.

Consider factors such as your climate, home design, and budget when selecting insulation for your home. A home energy professional may be able to help you decide what type of insulation is best for you.

The Home Energy Saver tool can also provide recommendations for your home .

Types of Insulation

Insulation is made from a variety of materials, and it usually comes in four types: rolls and batts, loosefill, rigid foam, and foam-in-place. The type of insulation you should choose depends on how you will use it and on your budget. Also visit Energy for more information about types of insulation.

  • Rolls and batts—or blankets—are flexible products made from mineral fibers, such as fiberglass and rock wool, as well as recycled fibers such as denim. They are available in widths suited to standard spacing of wall studs and attic or floor joists.
  • Loose-fill insulation is usually made of fiberglass, rock wool, or cellulose in the form of loose fibers or fiber pellets. It should be blown into spaces using special pneumatic equipment. The blown-in material conforms readily to odd-sized building cavities and attics with wires, ducts, and pipes, making it well suited for places where it is difficult to effectively install other types of insulation.
  • Rigid foam insulation is typically more expensive than rolls and batts or loose-fill insulation, but it is very effective in exterior wall sheathing, interior sheathing for basement walls, and special applications such as attic hatches.
  • Foam-in-place insulation can be blown into walls, on attic surfaces, or under floors to insulate and reduce air leakage. You can use small pressurized cans of foam-in-place insulation to reduce air leakage in holes and cracks, such as window and door frames and around electrical and plumbing penetrations. There are two types of foam-in-place insulation: closed-cell and open-cell. Both are typically made with polyurethane.

Caution: Installing foam insulation requires that you wear personal protective equipment, maintain adequate ventilation, and take other safety measures. Consider hiring a professional to install foam insulation.

Use higher R-value insulation, such as spray foam, on exterior walls and in cathedral ceilings to get more insulation with less thickness.

If your attic has enough insulation and proper air sealing, and your home still feels drafty and cold in the winter or too warm in the summer, your heating or air conditioning system may not function properly, or you may need to add insulation to the exterior walls. Consult with a home energy professional to evaluate whether your HVAC system has design or equipment issues, or if you need additional insulation.

If you replace the exterior siding on your home, consider adding insulation at the same time.