During bat-proofing, openings of what size or larger must be sealed?

• A. 3/8 inch
• B. 1/2 inch
• C. 1/4 inch
• D. 1 inch

Answer: (A)

Openings that bats can fit through are the key target in bat-proofing. Bats can squeeze through gaps as small as 3/8 inch, so any opening that size or larger should be sealed to prevent entry. This threshold guides where to focus sealing efforts around eaves, vents, chimneys, and other roof penetrations. Smaller gaps, those under 3/8 inch, are generally too small for a bat to pass, so they’re not the primary concern for exclusion. When sealing, use durable materials and, if bats are present, consider appropriate exclusion methods to ensure bats can exit but cannot re-enter before sealing.