Division of Energy
Residential Energy Efficiency - Caulking and Weatherstripping
Caulking is an easy, energy-saving project you can do yourself. It is relatively inexpensive - and very effective. In fact, it will usually pay for itself in energy savings within one year.
Caulking is a compound used for filling cracks, holes, crevices and joints on both the inside of your home. You will need only a few simple tools and a minimum of skill to caulk these areas. Start at the back of your house and work toward the front so that your skill level is improved by the time you caulk places that are visible.
Try to choose a mild day to tackle this project. The outside temperature should be above 400F for the caulk to be applied correctly. So, plan to caulk during the spring, summer or fall for best results. Old, cracked caulk should be removed before new is applied. Check your home repair center for a "puttying tool" that will make the job easier and provide a more professional look.
Where to Caulk
As a general rule, caulk should be applied wherever two different building materials meet on the interior or exterior of you home. Different building materials expand and contract at various rates. Through the years, with temperature extremes and caulk drying out, cracks develop between materials. Because these cracks allow air infiltration, the cracks need to be caulked.
On the interior of your home, you can check for air leakage by moving your hand around the windows and doors on a windy day. If you can feel air movement, you need to caulk and/or weatherstrip. You will probably be surprised to find how many spots are "air leakers"!
The following are areas that should be checked:
- Around door and window frames - inside and out; check window pane putty.
- Places where brick and wood siding meet.
- Joints between the chimney and siding.
- Between the foundation and walls.
- Around mail chutes.
- Around electrical and gas service entrances, cable T.V. and phone lines, and outdoor water faucets.
- Where dryer vents pass through walls.
- Cracks in bricks, siding, stucco and foundation.
- Around air conditioners.
- Around vents and fans.
- Wherever two different materials meet.
- Around electrical line penetrations in the attic and crawlspace.
The material used in sealing air leaks depends on the size of the gaps and where they are located. Caulk is best for cracks and gaps less than 1/4" wide. Expanding foam sealant is good for sealing larger cracks and holes that are protected from sunlight and moisture. Rigid foam insulation may be used for very large openings such as plumbing chases and attic hatch covers. Fiberglass insulation can also be used for sealing large holes, but it needs to be wrapped in plastic or stuffed in plastic bags because air can leak through fiberglass.