Along with weatherstripping, caulking is one of two essential techniques for sealing air leaks in your home. It is ideal for sealing gaps that don’t open and shut – for instance, where your fireplace or an air vent is built into the wall. It works best where cracks or gaps are less than ¼ inch wide. Caulking consists of applying a thick substance called caulk directly over gaps. The substance soon dries, forming an airtight barrier between the inside and outside. As an added bonus, caulking will also help prevent moisture from seeping into your home, which will help keep mold out, and it can be an effective barrier against insects.

Caulking should be done on both the interior and the exterior of your house.

On the exterior, the following locations should be caulked:

• In the joints between chimney and siding
• In the joints between eaves and gable molding
• In the joints between window sill and siding
• In the joints between window drip cap and siding
• In the joints between window sash and siding
• In the joints between windows and masonry
• On door frames
• In the joints between masonry or concrete parts (steps, porches, etc.) and main part of house
• On the inside corners formed by siding

Inside your home, caulk the following gaps:

• Where pipes enter
• Where vents exit
• Around duct vents
• Between fireplace and walls
• Between sheets of paneling
• Door frames
• Windows
• Baseboards (even if you have wall-to-wall carpeting)
• Fur downs
• Built-in cabinets
• Inside closets
• Outlets and Switchplates (Gaskets for outlets and switchplates can help prevent air leakage through the walls. Several types are now available and are easily installed. Remember to cut off electricity to the switch to prevent a shock hazard.)

No matter what material your caulk is made of, it won’t last forever, but expensive silicone types, which will be effective for 30 years, are almost always a good investment. If these home improvements are a temporary, intermediate step, if you are not concerned with the longevity of your caulking or if your choices are financially limited, consider the many other, cheaper varieties of caulk – manufacturers should list life expectancy on the product package. Be sure to follow package directions very carefully when caulking your home – if it’s not applied correctly it will not be effective at sealing your home.

Weatherization, Water & Energy Saving Products, Kits & Programs