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Insulation

Checking your home'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 while reducing your heating and cooling needs by up to 30% by investing just a few hundred dollars in proper insulation and weatherization products.

Insulation

Home Insultation Locations
Where to Insulate
Adding insulation in the areas shown here may be the best way to improve your home's energy efficiency.

Should I insulate my home? First, check the insulation in your attic, ceilings, exterior and basement walls, floors, and crawl spaces 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 roofs will resist the transfer of heat. The U.S. Department of Energy (DOE) recommends ranges of R-values based on local heating and cooling costs and climate conditions in different areas of the nation. For a more accurate and simpler method of determining your insulation needs, try the Interactive ZIP Code Insulation Program, which uses your zip code and some information about your house to tell you where to add insulation. The program was developed by the Energy Division of the Oak Ridge National Laboratory. State and local codes in some parts of the country may require lower R-values than the DOE recommendations, which are based on cost-effectiveness.

Although insulation can be made from a variety of materials, 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 your house. Batts are made to fit between the studs in your walls or between the joists of your 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 the 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), 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 stem walls, concrete slabs, and cathedral ceilings.

Insulation Tips

  • Consider factors such as your climate, building design, and budget when selecting insulation R-value for your home.
  • Use higher density insulation, such as rigid foam boards, in cathedral ceilings and on exterior walls.
  • Ventilation plays a large role in providing moisture control and reducing summer cooling bills. Attic vents can be installed along the entire ceiling cavity to help ensure proper airflow from the soffit to the attic, helping to make a home more comfortable and energy efficient.
  • Recessed light 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 your 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.

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. homes should have between R-22 and R-49 insulation in the attic.

If your attic has ample insulation and your home 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 as well. 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.

New Construction
 

For new construction or home additions, R-11 to R-28 insulation for exterior walls is recommended for most of the country. To meet this recommendation, most homes and additions constructed with 2 x 4 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 greater than R-20, you may want to consider building with 2" x 6" framing instead of 2" x 4" framing to allow room for thicker wall cavity insulation - R-19 to R-21.


Visit the Insulation Contractors Association of America's web site for product information and more on hiring insulation contractors.

Weatherization
 

Warm air leaking into your home during the summer and out of your home during the winter can waste a substantial portion of your energy dollars. One of the quickest dollar-saving tasks you can do is caulk, seal, and weatherstrip all seams, cracks, and openings to the outside. You can save 10% or more on your energy bill by reducing the air leaks in your home.

Weatherization Tips

Energy Escape Route Pie Chart
How Does the
Air Escape?

Air infiltrates into your through every hole, nook and cranny. About one third of this air infiltrates through openings in your ceilings, walls, and floors.
  • First, test your home for air tightness. On a windy day, hold a lit incense stick next to your windows, doors, electrical boxes, plumbing fixtures, electrical outlets, ceiling fixtures, attic hatches, and other locations where there is a possible air path to the outside. If the smoke stream travels horizontally, you have located an air leak that may need caulking, sealing, or weatherstripping.
  • Caulk and weatherstrip doors and windows that leak air.
  • Caulk and seal air leaks where plumbing, ducting, or electrical wiring penetrates through exterior walls, floors, ceilings, and soffits over cabinets.
  • Install rubber gaskets behind outlet and switch plates on exterior walls.
  • Look for dirty spots in your insulation, which often indicate holes where air leaks into and out of your house. You can seal the holes by stapling sheets of plastic over the holes and caulking the edges of the plastic.
  • Install storm windows over single-pane windows or replace them with double-pane windows. Storm windows as much as double the R-value of single-pane windows and they can help reduce drafts, water condensation, and frost formation. As a less costly and less permanent alternative, you can use a heavy-duty, clear plastic sheet on a frame or tape clear plastic film to the inside of your window frames during the cold winter months. Remember, the plastic must be sealed tightly to the frame to help reduce infiltration.
  • When the fireplace is not in use, keep the flue damper tightly closed. A chimney is designed specifically for smoke to escape, so until you close it, warm air escapes - 24 hours a day!
  • For new construction, reduce exterior wall leaks by either installing house wrap, taping the joints of exterior sheathing, or comprehensively caulking and sealing the exterior walls.