Insulation 101

Basic facts on choosing and installing insulation in existing homes.

This diagram shows the priorities for installing insulation in homes.

Need to trim some dollars from your energy budget? Consider upgrading your home's insulation.

Adding insulation is one of the most cost-effective ways to reduce energy use, especially if you live in an older home. Homes built before the widespread adoption of modern energy codes are prime candidates for an insulation upgrade.

The amount of insulation recommended for different areas of your home is specified by R-value. R-value is a measurement of resistance to heat flow. As R-values get higher, insulating values increase.

Insulation gets its power from the air spaces it traps, not the actual insulation material. Compressing insulation actually decreases its effectiveness; that's why you shouldn't try to cram a six-inch fiberglass blanket into a three-inch space. Instead, opt for a thinner blanket.

Adding insulation in attics, crawl spaces and basements can be relatively easy. On the other hand, adding insulation in existing walls or vaulted ceilings can be expensive and extremely difficult, if not entirely impossible.

The most important place to add insulation in most existing homes is ceilings under unconditioned attics. Attics can steal your home's heating and cooling since their temperatures can be higher than 120 degrees in the summer and the same as the outdoor temperature in the winter. The minimum recommended insulation level for attics in Walton EMC?s service area is R-30.

Knee walls, short walls adjacent to attic spaces in upstairs areas, also need attention. Although called walls, knee walls are more like ceilings in a thermal sense. And even though knee walls may be insulated when the home is built, insulation commonly falls out because of gravity and poor installation. Try to insulate knee walls to R-19.

Don't forget ductwork that runs through attic spaces. Un-insulated attic ductwork can lose up to 30 percent of the cooling your air conditioning produces. That means you're paying 30 percent more than you should in energy bills. Ductwork should be insulated with a minimum of R-6 foil backed insulation. Joints in ducts should be sealed with mastic. You'll want to call a professional for duct insulation and sealing.

Many floors over crawlspaces are relatively easy to insulate. Besides reducing heat loss in the winter, insulating floors can help tile and linoleum feel warmer. The recommended level of floor insulation for our area is R-19.

Installing insulation yourself can save even more. Be sure to use protective equipment, like respirators, gloves and long sleeves. If the areas are difficult to access, require loose-fill insulation or if you?re not sure, it?s best to call a pro.

Installing the insulation properly can be almost as important as the amount you decide to install. Gaps and compressed areas can lower R-value by as much as 30 percent. And adding insulation won't solve problems caused by air leaks in the home's thermal envelope. It's best to seal air leaks before adding insulation.

Existing Home Insulation Guide

Fiberglass Blankets and Batts
Use: attics, knee walls, floors
R-value: R-3.1 to R-4.2 per inch
Made from: molten sand and up to 30 percent recycled glass
Installed by: do-it-yourselfers, professionals
Advantages:

Fiberglass Loose-Fill
Use: attics
R-value: 2.2 to 2.6 per inch
Made from: molten sand and up to 30 percent recycled glass
Installed by: professionals
Advantages: