Plug Those Drafty Walls

Cracks that let air escape right through your home's insulation rob you of heat. These leaks are common in the walls of most homes. And they also occur around doors, chimneys, plumbing vents, foundation cracks and other exterior wall openings.

If you have a new home, it may have been insulated with the latest techniques--using gaskets, caulk and plastic.

But if you're not so fortunate, you can rely on a long-lasting, flexible caulk and a can of expanding foam to plug the leaks. It helps to think of the inside of your interior walls and ceilings as air barriers. You can seal with caulk all the edges and the places they intersect, such as electrical boxes and windows.

Another common problem is inadequate or no insulation in certain areas of the home, including the attic. To add insulation or to install new insulation, you can rent the right tools, including an insulation blower, to do the job yourself.

Backdrafts from your furnace, water heater and fireplace can rob your home of heat, too. Make sure they are properly vented. Stopping air leaks partially resolves another problem that cuts down on the effectiveness of your insulation. You have to control moisture.

The reason is that warm air leaking through a stud cavity carries moisture, which condenses on cool sheathing. This wets both the sheathing and the insulation. And since it's difficult for wet wood to dry in a wall cavity, it can rot.

Plugging leaks is only a partial solution. Warm inside air carries water vapor that can pass right through the drywall and condense on outer sheathing. Block this water vapor movement by placing a plastic vapor barrier behind the drywall.

Although a plastic vapor barrier works best, painting the wall is a cheaper alternative. Two coats of an oil or alkyd-based paint over one primer coat usually will do the job.