Preventing Infiltration

Infiltration accounts for a significant part of the total heat loss, and sealing the sites of air leaks by caulking or weather-stripping should be the first step to reduce energy waste and heating and cooling costs. Weatherizing requires some work, of course, but it is relatively easy and inexpensive to do.

Caulking can be applied with a caulking gun inside and outside where two stationary surfaces such as a wall and a window frame meet. It is easy to apply and is very effective in fixing air leaks. Potential sites of air leaks that can be fixed by caulking are entrance points of electrical wires, plumbing, and telephone lines; the sill plates where walls meet the foundation; joints between exterior window frames and siding; joints between door frames and walls; and around exhaust fans.

Weather-stripping is a narrow piece of metal, vinyl, rubber, felt, or foam that seals the contact area between the fixed and movable sections of a joint. Weather-stripping is best suited for sites that involve moving parts such as doors and windows. It minimizes air leakage by closing off the gaps between the moving parts and their fixed frames when they are closed. All exterior doors and windows should be weatherized. There are various kinds of weather-stripping, and some kinds are more suitable for particular kinds of gaps. Some common types of weather-stripping are shown in Fig. 61.