Metal hardware cloth or aluminum window screen is not acceptable, as it may cause injury to bats. Mesh must be securely stapled every two inches across, up, and down, such that it does not sag, buckle, or curl. Staples must be flush with the roosting surfaces, such that no sharp edges could come into contact with bats. Screws, nails, staples, mounting hardware, splinters, or other sharp objects must not protrude into the roosting chambers. Any screws, nails, staples, or mounting hardware used must be an exterior grade, galvanized, or non-corroding.
Screws are preferable to nails, as they hold better over time, creating a more durable product.
Decorative vents may be allowed, provided their size and position are adequate. Unvented houses are acceptable if intended for cool climates only, which must be clearly stated in enclosed literature and advertising. Any plywood used must be exterior grade. Boards should come from quality stock such as cedar or pine. Overall construction must reflect that the bat house is a quality product.