New caulk can end draft from windows

Dear Jim: It seems to be drafty in my home whenever it is windy outdoors. I have noticed some caulk around the windows is dry and hard. Where should I check for areas to caulk and what is the best caulk to use? – Karen H.

Dear Karen: If the caulk feels dry and hard, it is probably time to replace it with new caulk. Even though you may not see noticeable cracks and gaps, the caulk is probably not adhering well. If you dig in it with the tip of a screwdriver, pieces may fall out.

One simple method to find areas that need to be caulked is to hold the back of your hand near windows and doors on windy days. You will be able to feel serious air leaks. Also, move a lighted stick of incense around all the windows and doors and observe the trail of smoke.

Windows and doors are the obvious locations for air leakage, but they are not always the worst culprits. The sill area, where the walls rest on the foundation, is often the area of greatest air leakage.

Check for gaps around the wiring where the main electrical service enters your home. Do the same where the telephone and cable lines come indoors. Holes for outdoor faucets are often bigger than the diameter of the pipe.

Inspect any penetrations in the ceilings for recessed lights, vent fans, ceiling fans, etc. You will probably have to get up into your attic and move some insulation away to check these. While you are up there, also check for gaps where the plumbing vent pipes pass through the attic floor.

Since the old caulk is hard and brittle, it probably was not silicone, so a caulk remover (softener) chemical should make it easier to remove the old caulk. These chemical removers are not as effective on silicone.

For indoors with its small temperature changes, latex caulk is effective. It lasts about 20 years and is paintable. Instead of painting it, kits are also available to mix paint with the caulk to tint it for a perfect match.

The most common caulk used is acrylic latex with silicone. It costs about a dollar more per tube than plain acrylic latex, but it lasts years longer and is more durable. It also is paintable and cleans up with soap and water.

Silicone caulk is best where flexibility is required, often outdoors. Not all silicone is paintable, so it is available in several colors. It is more difficult to lay a smooth bead with silicone, it has an odor as it cures and cleanup is more difficult.

For large gaps, expandable urethane foam is a good choice. It also adds insulation value. It is available in low- and high-expansion formulas. The low-expansion type is better for most applications.