Angie's LIST Guide to
Insulation and weatherstripping

Attic insulation can settle over time and need a fresh layer. The builder may have insulated your walls, but neglected other parts of the home exterior where heat can escape.



How good is your insulation

insulation types

Left, sections of fiberglass insulation fitted between wall studs.
Right, spray foam insulation applied directly to unfinished walls.

Properly insulating your home, including sealing drafts around windows and doors, can save you 10 to 20 percent on yearly utility costs.

But how do you judge how well your home is insulated? Since insulation can deteriorate over time, a home that was once well-insulated may no longer have optimum protection.

One check homeowners can do themselves is to go up in the attic and visually inspect the exposed insulation. A typical unfinished attic will have loose insulation piled on the attic floor as the main barrier to heat loss. These materials settle over time, and that's generally a good thing because the protection is better as the insulation becomes more compact. However, one rule of thumb is that if you can see the floor joists, you no longer have enough insulation to do the job.

Although attic insulation essential because heat rises, you also need adequate protection in walls, crawl spaces and basements. These can be much more difficult to inspect on your own.

For the best assessment, consider having an energy audit in which infrared technology can detect gaps in insulation within exterior walls.

Measuring insulation effectiveness

R-value insulation map

The performance of insulation or its ability to resist heat flow is determined by what is called an "R-value." A higher R-value translates into more insulating power.

There are various R-value recommendations for walls, attics, basements and crawlspaces as well as for geographic locations.

Energy Star's recommended insulation level for most attics is R-38 (or about 12 to 15 inches, depending on the insulation type). In colder climates, insulating up to R-49 may be recommended.

When you hire a professional to insulate your home, ask about the R-value the company intends to install. If your home is close to the cut-off between one region and another you may want to opt for a higher R-value than is necessarily required for your zone. Remember that the R-value rating is only as good as the quality of the installation.


If you can feel cold air coming in around doors or windows, you may be able to address the problem yourself with weatherstripping.

Weatherstripping is a pad of foam or felt used along the closing edges of windows and doors.

A good product should be able to withstand friction, temperature changes, UV rays and wear and tear. Also, some types of weatherstripping are visible while others remain hidden.

Most common weatherstripping options include:

Felt and open cell foam: This type of weatherstripping is considered easy to apply but generally ineffective against weather extremes and inefficient at blocking air flow.

Flexible vinyl: Slightly more expensive, this variety holds up relatively well and resists moisture.

Metal: Available in bronze, copper, stainless steel and aluminum, these weatherstripping options last for years and can be matched to existing door hardware. Door sweeps can be installed at the bottom of a door and can have rubber or bristles to reduce the amount of air that can flow under the door when closed.

Door-bottom edge: This stripping is available at most home improvement or building centers. But better quality stripping may be available in bulk quantities at reasonable prices through a commercial garage-door company.


We have very little insulation right now, maybe 5 inches of fiberglass strips. What is the best type of insulation to add and why? I have received several different quotes, and they all say to go with what they have.

My home gets very hot upstairs. 30 years old and need insulation in Atic and maybe walls not sure.

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