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The Sensible Home

Caulk fills the gaps with ease

Published May 19, 2007


Q: I noticed cold air leaking indoors all winter. The caulk around doors and windows looks bad and should be replaced. Where else should I look for air leaks? Is there one caulk I can use for everything?

A: Windows and doors are the most obvious places outdoor air can leak into a house, but there are many others. Walk around the exterior of your house and look for any cracks or tiny gaps. On a windy day, it does not take a very large opening to create a substantial draft indoors.

Other than apparent gaps, check any place two dissimilar materials meet and are supposed to be sealed. Some spots to check are where outdoor faucets penetrate the wall, soffits meet siding, corner trim meets the walls, etc. Dissimilar materials expand and contract different amounts with temperature changes, so caulking often fails there first.

When caulk cures, it should still be flexible and have a tough, durable skin. Even though the old caulk may look dirty with tiny surface imperfections, it may still be fine. Using a long thin screwdriver, try to poke into the caulk around your windows and doors. If the caulk is still flexible and appears to be adhering to the surfaces, it is probably okay. The tiny test holes will not affect its performance.

Many types of caulk are available for specific sealing projects around your house. If I had to buy just one type of caulk to use throughout my house, I would select siliconized acrylic latex caulk. DAP Alex caulks use this basic formula and they are supposed to last up to 35 years.

Since these caulks have an acrylic latex base, they can be cleaned up with just soap and water. They can also be painted to match exterior and interior trim. If you are in a hurry to finish, DAP has a new quick-drying caulk that can be painted within 40 minutes of application. Red Devil makes a caulking kit that you can tint yourself with paint to match the trim. They also offer a new caulk that can also be used as an adhesive.

Straight silicone caulk is still one of the most durable sealing materials. It is ideal where great flexibility is needed between dissimilar materials. It functions well in either very cold or hot conditions. Its drawbacks are higher cost, more difficult cleanup than with latex, may not be easily painted, and smell while it cures.

James Dulley is a mechanical engineer and do-it-yourselfer. Send questions to James Dulley, The Sensible Home, St. Petersburg Times, 6906 Royalgreen Drive, Cincinnati, OH 45244. Visit his Web site at to tour his energy-efficient home, post questions for other readers and find other information.



Caulk sources

The following companies offer caulks.

- DAP: toll-free 1-800-543-3840,

- Fomo: toll-free 1-800-321-5585,

- Geocel: toll-free 1-800-348-7615,

- OSI: toll-free 1-800-321-3578,

- Red Devil: toll-free 1-800-423-3845,


[Last modified May 18, 2007, 10:44:47]

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