The most satisfactory and permanent method of preventing nuisance bats is to exclude them from buildings. Bats can enter through a 3/8-inch diameter opening. Finding all these potential entry points is a tedious process. If you are truly certain that you don't have bats or other wildlife (including bees) using these gaps, then you may seal all gaps of 1/4 x 1 1/2 inches (0.6 x 3.8 cm) and openings 5/8 x 7/8 inches (1.6 x 2.2 cm) or greater. Caulk, 1/4-inch weave hardware cloth, and flashing are all good ways to secure openings. Although manufactured stainless steel chimney caps won't stop a bat from using the chimney, they can help and are important to install for other reasons. One advantage with bat proofing is that it often reduces heat loss from your home as well. Additional informaiton can be found at the Web site of the Internet Center for Wildlife Damage Management ICWDM .

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