Heating Insulation

Checking a home or building’s insulating system is one of the fastest and most cost-efficient ways to use a whole-house approach to reduce energy waste and maximize your energy dollars. A good insulating system includes a combination of products and construction techniques that provide a home with thermal performance, protect it against air infiltration, and control moisture. You can increase the comfort of your home of office while reducing your heating and cooling needs by up to 30%.

What is insulation?

Insulation can be made from a variety of materials, but it usually comes in four types: batts, rolls, loose-fill, and rigid foam boards. Each type is made to fit in a different part of a home or building.

Batts are made to fit between the studs in walls or between the joists of ceilings or floors. Batts are usually made of fiber glass or rock wool. Fiber glass is manufactured from sand and recycled glass, and rock wool is made from basaltic rock and recycled material from steel mill wastes.

Rolls or blankets are also usually made of fiber glass and can be laid over the floor in an attic. Loose-fill insulation (usually made of fiber glass, rock wool, or cellulose) is blown into the attic or walls. Cellulose is usually made from recycled newsprint treated with fire-retardant chemicals.

Rigid foam boards are made of polyisocyanurate, extruded polystyrene (XPS or blueboard), expanded polystyrene (EPS or beadboard), or other materials. These boards are lightweight, provide structural support, and generally have an R-value of 4 to 7 per inch. Rigid board insulation is made to be used in confined spaces such as exterior walls, basements, foundation and crawl space walls, concrete slabs, and cathedral ceilings.

Where do I start?

Check the existing insulation in your home or office building to see if it meets the levels recommended for your area. Insulation is measured in R-values—the higher the R-value, the better your walls and roof will resist the transfer of heat. The U.S. Department of Energy recommends ranges of R-values based on local heating and cooling costs and climate conditions in different areas of the nation.

The easiest and most cost-effective way to insulate your home is to add insulation in the attic. To find out if you have enough attic insulation, measure the thickness of insulation. If there is less than R-22 (7 inches of fiber glass or rock wool or 6 inches of cellulose) you could probably benefit by adding more. Most U.S. home should have between R-22 and R-49 insulation in the attic.

If your attic has ample insulation and your home or building still feels drafty and cold in the winter or too warm in the summer, chances are you need to add insulation to the exterior walls. This is a more expensive measure that usually requires a contractor, but it may be worth the cost if you live in a very hot or cold climate.

You may also need to add insulation to your crawl space. Either the walls or the floor above the crawl space should be insulated.

For new construction or building additions, R-11 to R-28 insulation is recommended for exterior walls depending on your location. To meet this recommendations, most new construction and additions constructed with 2 by 4 inch walls require a combination of wall cavity insulation, such as batts and insulating sheathing or rigid foam boards. If you live in an area with an insulation recommendation that is great than R-20, you may want to consider building with 2 by 4 inch framing instead of 2 by 4 inch framing to allow room for thicker wall cavity insulation (R-19 to R-21).

Insulation Tips

  • Consider factors such as climate, building design, and budget when selecting insulation R-value.
  • Recessed lighting fixtures can be a major source of heat loss, but you need to be careful how close you place insulation next to a fixture unless it is marked “I.C.”—designed for direct insulation contact. Check local building codes for recommendations.
  • As specified on the product packaging, follow the product instructions on installation and wear the proper protective gear when installing insulation.



U.S. Department of the Interior

Greening of the Interior