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Insulate Insulate Insulate
Having the right insulation is the first step toward household comfort and energy savings. No matter how well-sealed the walls are, and no matter how good your heating and cooling system is, your home will often be drafty and unevenly conditioned if your insulation is inadequate.
Insulation is rated according to its R-Value, or its ability to resist heat flow, with a high R-Value being a greater resistance. Follow the Department of Energy's insulation guidelines and your house will be more comfortable, a little quieter, and will cost less to heat and cool than if you had gone with the local code requirements. Proper installation is critical; gaps and compressed areas will dramatically reduce effectiveness.
But what is the right insulation? Well, it all depends on:
If you are having a new house built, don't just go with the insulation required by the building code. The Department of Energy (DOE) has recommended insulation levels for: (most importantly) ceilings and attics, walls, basements, and crawlspaces.
Adding more insulation while you are remodeling is very cost effective when you are tearing out walls and messing with the attic anyway. And use the Energy Efficient Rehab Advisor to see how much it will cost to add this insulation and how much you'll save in utility costs. Most older homes, especially those built before 1975, have much less insulation than DOE recommends.
Generally, for comfort and energy savings, the attic is the best place to add insulation. And if your attic is easily accessible it might be easy to add ceiling insulation, even if you are not doing any remodeling at all. Just be sure when you are adding insulation that a vapor retarder is not applied between layers of insulation. When adding additional insulation, do not use insulation that comes with a vapor retarder (paper or aluminum-like sheating) integrally attached. Moisture can be trapped below this new vapor retarder, causing damage to the insulation, ceiling and paint below the vapor retarder.
Before You Insulate
Conduct thorough air sealing. Adding insulation may make some air leaks difficult to access. The insulation itself typically will not stop these leaks. Air flowing through the insulation will waste energy. Moist air can damage the insulation and reduce its effectiveness.
Control moisture. Rain can penetrate through improper flashing and leaks around doors, windows, chimneys and poorly-installed siding. If you're remodeling, fix these problems and install a vapor retarder. Remove any existing insulation that has gotten wet.
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.
**Caution: Many types of insulation used before the 1978 contain asbestos, which, if disturbed, is a dangerous material.
Types of Insulation
There are four basic types of insulation: loose fill, batts and blankets, rigid board and spray foam. The most appropriate type of insulation to use will vary due to the different construction techniques, whether your house is being built or being remodeled, and applicable code requirements.
Batt and blanket insulation, the most common type, and the easiest to work with for do-it-yourselfers, is made of mineral fiber -- either processed fiberglass or rock wool -- and is used to insulate below floors, above ceilings, and within walls. Generally, batt insulation is the least expensive wall insulation material but requires careful installation for effective performance.
Loose-fill insulation, for new or remodeled homes, includes loose fibers or fiber pellets that are blown into building cavities or attics using special equipment. It generally costs more than batt insulation, but it offers reduced air leakage through the wall cavity plus improved sound deadening.
Rigid board insulation is commonly made from fiberglass, polystyrene, and polyurethane and comes in a variety of thicknesses with a high insulating value (approximately R-4 to R-8 per inch). This type of insulation is used for reroofing work on flat roofs, on basement walls, and as perimeter insulation at concrete slab edges, and in cathedral ceilings.
Spray foam insulation is a two-part liquid containing a polymer (such as polyurethane or modified urethane) and a foaming agent. The liquid is sprayed through a nozzle into wall, ceiling, and floor cavities. It expands while spraying into a solid cellular plastic with millions of tiny air-filled cells that fill every nook and cranny. Spray foam insulation should only be applied by professionals. It is commonly used for retrofits because it is good for irregularly shaped areas and around obstructions. Spray foam materials cost more than traditional batt insulation. However, since spray foam forms both an insulation and an air barrier, it can be cost competitive with batt insulation because it eliminates the steps for air-tightness detailing (such as caulking, applying housewrap and vapor barrier, and taping joints).
Other Insulating Systems
Other proven insulating systems are also available, and can be found on PATH's Technology Inventory.
For new construction you should always consider Insulated Concrete Forms (ICFs) when building concrete foundations and basements, and use ICF Walls when building concrete walled homes. Straw Bale construction provides excellent thermal (R-50) and acoustical insulation.
Insulative Vinyl Siding is a good choice when you are replacing your siding, especially when you want additional insulation but find it impractical to add spray or batt insulation.
Content updated on 10/27/2005
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