The time and money you invest in weather-stripping and caulking windows and doors can pay off faster than almost any other home improvement you can make, even when your house is already well insulated. From 15 to 60 percent of the heating and cooling your house needs is due to air exchange. Warming the air that leaks into the house in winter, or, conversely, cooling the air that leaks into it in the summer, takes energy and costs you money. In addition to the benefits of energy savings, caulking is the easiest and best way to prevent water intrusion, which can lead to rot, decay, mold and termite infestation.

Where to Caulk: Exterior
Sealing exterior cracks and seams is an important part of home
maintenance. It reduces entry of air, dirt, and moisture into the house
and contributes to lower heating and cooling costs:

Among the most important exterior areas of a house requiring attention are:

Where to Caulk: Interior
Sealing each room on the inside is the only way to prevent jets of air from coming inside. A good interior caulking job will increase the comfort of your home immeasurably. You may find gaps so wide that foam caulk is required. Tape a piece of tissue or plastic wrap to a pencil and check the following places for air leaks:

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.)

Do-it-yourselfers will find many caulking compounds in a wide range of prices. Most materials are packed in cartridges and can be applied easily with a caulking gun. For large jobs, 5-gallon containers of caulking for guns are used. Manufacturers usually print on each cartridge a description of the material, its performance quality, and directions for application.

Caulking materials that adhere to wood, glass, metal, plastic, and masonry should be selected since these materials expand and contract. Resistance to weathering, cracking, shrinkage, water, and mildew are also important. Some manufacturers will state the life expectancy of their product, if properly installed, inside or outside the home.

Follow these pointers for successful application of caulking materials:

1. Use a caulk gun with an automatic release. When you press the release lever the caulk stops flowing instantly. This device makes caulking so much less messy it is well worth the extra dollar or so for the caulk gun.
2. Cut the tip of the cartridge at an angle. Cut only about 1/4" off the tip so that the hole is 1/8" to 1/4" in diameter. This is adequate to create a bead of caulk large enough for most cracks.
Remove old, dried sealing materials. Clean area with a solvent to remove grease or other substances that would prevent a tight bond.
Deposit caulk at the bottom of the seam so it fills without bubbling.
Never apply caulk to a porous surface.
Prime before application.
Never skimp. Use enough caulk to fill the crack or seam.
If caulk shrinks during drying, reapply.
Push the tip over the caulk so it forms a smooth bead across the area being sealed.

Fifty years of evolution in silicone caulks brings us an assortment of products formulated for just about every substrate. Although the competition is stiff in most areas, there is no substitute for the strength of silicone on hard surfaces like metal, glass, and tile.

There are a wide range of water-base caulks, from painter’s caulk to elastomeric sealants. Latex caulks can be used just about anywhere as long as you choose the right product for the job. Some water-base products are flexible and weather resistant for exterior joints; others are intended to hide only interior seams that are to be painted.

Kitchen and bathroom caulks resist water and mildew. Most caulks are mildew resistant, which means that mildew will not degrade the product. Mold and mildew, though, can stain cured caulk. So in the kitchen and bathroom where water and mildew are common, a product with an added biocide is a good idea.