As of October 2015, free bat-house plans are posted online by This Old House, Bat World Sanctuary and Bat Conservation International. This Old House offers moderately difficult plans that take three to four hours to complete. The site also has a video that demonstrates the construction.
Bat World Sanctuary has PDF bat-house plans that are suitable for a beginning builder. The houses are appropriate for bats that live in crevices, such as little brown and big brown bats. Bat Conservation International presents a bat-house builder's handbook. It has plans for single-, two- and four-chamber houses. Additional information includes characteristics of a successful bat house, such as how to mount, maintain and clean it.