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Bat House Design Guidelines


Research Reveals bats prefer larger houses
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bat house cert logo
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FBN has worked with Merlin Tuttle and
BCI on a variety of projects for over 30 years
MTBC and BCI
Bat House Certification
and Bat Aproved Logo

FBN’s founder, Laura Finn,
was a contributing editor to
the 2013 revision of BCI’s BHBHB

BCI Bat House
Builders Handbook

Bat House Minimum Design Standards and Recommendations:

When it comes right down to it, bat houses are no different than any real estate — occupancy is influenced by both architectural design and location, location, location. Bats are all too often found in sub-optimal locations when access to suitable roosts is limited. Please don't provide bats with suboptimal roosting sites, it doesn't help in the long run and it's easy to give them what they need. The suggestions below are based on data from long term research conducted by Fly By Night and data from BCI’s Bat House Research program.

The following minimum guidelines are incorporated in to every bat houses we build — our standards are high. We refuse to put our name on smaller and simpler designs that lack the quality we are proud of and have declined offers from others who want to build bat houses for us, but our goal is not to simply sell a lot of bat houses. Our goal is to offer an attractive and effective bat house that provides bats with safe, quality and long-term roosting sites.
Our bat houses are proven sucessful at providing homes for homeless bats.

Research shows that

  • Bats prefer larger bat houses.
    • Larger is always better, avoid tall narrow bat houses with widely spaced crevices.
    • Three or more interior chambers are necessary to provide the needed thermal profile conditions.
    • ***Small single chamber bat houses are acceptable ONLY IF mounted directly onto to the side of a structure for thermal stability.

  • Optimal roosting chambers
    • Vertical crevice height should be 18—24 inches
    • Horizontal crevice width of 24 inches. (minimum)
    • Crevice spacing of 3/4 —7/8 inches
    • ***Larger spacing increases the potential for mud daubers, wasps and other competition.

  • Bats prefer bat houses that are warm, dry AND well ventilated.
    • A medium shade of paint or stain will enhance solar warming, but ventilation is important to avoid over heating
    ***add link to regional map for bat house shade***

  • Caulked and painted bat houses are more likely to be occupied than bare wood bat houses.
    • Use of a high quality water based caulking on all joints and latex paint or wood sealer will add years to your bat house and keep the occupants warm and dry.
  • The bat house should be easy to enter / exit and easy to hang on.
    • A 4” - 6” landing pad will make it easy for bats to enter.
    • All roosting surfaces should have a rough texture that bats can easily climb and hang on
        • ***Roosting substrate is very important, bats have difficulty hanging onto smooth surfaces and there is an increased risk of pups falling from the roost.
    • Surfaces should be roughened or grooved manually.
        • ***We strongly discourage attaching screen or other materials to roughen a smooth surface. Our early research revealed significant problems caused by screen failure.

Questions About Bat Houses or Alternate Roost Options??
Contact Us
Fly By Night, Inc. The Bat Specialists
P.O. Box 562
Osteen, FL 32764-0562
Phone: 407-414-2142
E-mail Us (laura*at*flybynightinc.org)



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