Weatherization

Cost: $15-30,000

You can save a little energy by snugly wrapping an insulating blanket around your hot water heater. You can save a lot more by snugly weatherizing and insulating your whole house.

"Weatherizing" means keeping moisture out and conditioned air in. A well weatherized house will stay dry and warm in the winter, and dry and cool in the summer.

To weatherize your home, start by looking for moisture problems, then conduct an energy evaluation. A mini hygro-thermometer that measures relative humidity and temperature is a good tool to use to find moisture problems. Take measurements in your basement or crawl space, in your living area (including kitchen and bathrooms), and in your attic. If you find a relative humidity reading over 55% during heating season, you have a serious problem.

Moisture in your basement could be seeping up through the floor, or entering through the wall. For moisture seeping up through the floor, consider putting down a vapor barrier such as polyethylene plastic. Overlap and tape the seems so moisture is trapped underneath the vapor barrier. For moisture entering through the wall, check grading around the foundation of your home. When warmer weather arrives, you may need to re-grade to slope the ground away from your home. Identify where water may be flowing and re-direct it away from your home.

High humidity levels in your bathroom or kitchen are a sign that the exhaust fans are not working. Kitchens and bathrooms should have exhaust fans that vent directly to the outside. Windows are not effective at removing moisture from bathrooms, especially in the winter when they are unlikely to be left open when the bathroom is in use.

Moisture in your attic could indicate a roof leak or air leaks allowing warm moist air from your heated living area to rise into your cold attic, where moisture may start to condense. First check to make sure that you don't have any ice dams or active leaks due to improper flashing or roof penetrations. Once you've determined that no moisture is coming from the roof, then check for warm moist air rising from rooms below.

The access to your attic should be tightly air sealed. If you have an attic hatch, build a tight-fitting door with eye hooks or sash locks that allow you to close the door tightly against weatherstripping to keep air from leaking into the attic. In your attic, took for holes around pipes and wires. Use spray foam to seam any holes between your heated space and your attic. Check the top of your walls to make sure you have a tight air seal and that no air can come up through your walls into your attic. Ideally you should have a continuous air seal and vapor retarder on the warm side (the bottom) of the insulation in your attic.

After you have inspected and sealed air leaks in your basement and attic, check your windows for drafts. Rather than replacing your windows, you may be able to install interior storm windows that fit tightly into your windows and block air flow. Interior storm windows can be made from wood frames covered with heat-shrink plastic. Weatherstripping around the edges of the frames allows the storm windows to fit snugly in the window opening and completely block air flow.

In general, it's more important to stop air flow than to add insulation. Start by first identifying drafts and stopping air flow. Once you've tightened up your house with spray foam and weatherstripping, then it's time to add insulation to the attic or the walls. Blown-in cellulose is an affordable material that is safer and more effective than fiberglass. If you already have fiberglass in your attic, you can blow a "top coat" of cellulose to cap it off and prevent air currents from scrubbing heat out of your fiberglass insulation.

With patience and persistence, weatherizing a home built before 1980 can cut its heating bills in half.