Merlin Tuttle's Bat House Seal of Approval
(please click HERE for the Bat Conservation International Certification Information)
We are happy and proud to be a Merlin Tuttle's Bat Conservation (MTBC) approved bat house vendor. MTBC awards their seal of approval to vendors whose houses meet their strict standards for construction and advice.
MTBC General Guidelines for Construction
Successful bat house construction comes in many forms. The following specifications serve as general guidelines for construction.
- Roosting chambers must be 3/4 - 1" wide (front to back). The best crevice size for most North American bats is 3/4". Houses may have up to 1.5" chambers, provided they are specifically built and marketed for larger species such as pallid or Florida bonneted bats. Advertising must also state that 1.5" chambers are more attractive to wasps and other non-target animals, requiring more frequent monitoring. In multi-chamber houses, we will accept one rear chamber of 1.25" in recognition of potential use by big brown or free-tailed bats.
- Roosting chambers must be at least 14" tall (20" or more is preferred) and at least 14" wide. "Rocket style" houses with continuous (360°) chambers are an exception. Depending on materials used, bat houses with roost chambers wider than 16" may require spacer blocks between partitions to prevent warping. Proven designs of different spacing (in width and/or height) may be considered on a case by case basis.
- Bat houses must include a landing area, extending at least 4" below the entrance (6" preferred), or partitions may be recessed 3-4", such that bats may land on the inside, protected from owl attacks.
- All interior and landing surfaces must have adequate texture to provide footholds for bats. Surfaces may be hand-scored, mechanically cross-cut, or covered with heavy-duty mesh (e.g. Gutter Guard). For plywood, grooves must not penetrate beyond the outermost lamination, which is normally approximately 1/8" thick. In non-laminated lumber, grooves can be 1/8" deep at 1/2" intervals. If used, mesh must be securely attached with exterior-grade staples such that it cannot sag, curl, or buckle. Sharp edges and/or protruding staples cannot be permitted.
- Bat houses must have durable, tight-fit construction (no unplanned gaps). All exterior seams must be caulked or glued (latex calk much preferred) during assembly to prevent drafts or warping. All screws, staples, nails, and metal components must be exterior-grade and must not protrude into roost chambers.
- All exterior parts of wooden houses must be at least 1/2" thick. If plywood is used, it must be graded ACX or BCX for outdoor use. When cedar, pine, or other lumbar is used to construct fronts or backs, it must be shiplap or tongue and grooved joints. Roofs or sides are best cut from cedar or pine lumber.
- Outer shell must consist of either UV-resistant plastic OR wood treated with either water-based sealant or three coats of paint (preferably both). Pressure treated wood is acceptable only when thoroughly coated with a quality sealant, such as Kilz (all-purpose interior/exterior primer), followed by three coats of water-based paint. Additionally, sealing and painting of all interior surfaces may extend lifespan and is much preferred but must not lessen footing by filling in scored or cut grooves.
- Half-inch ventilation slots are required for most houses. Positioning and size are dependent on house design. Unvented houses are acceptable only if specifically intended and advertised for cool climates.
- For bat house kits, adequate instructions must be provided for customers to caulk, paint, and assemble the house according to the guidelines listed above. Instructions also must contain adequate guidance for mounting and placement.
- Advertising and any instructions or literature must be approved by MTBC. Unsubstantiated or misleading claims are not permitted.
Seal of Approval Program
Follow-up with approved manufacturers is conducted bi-annually.
If you are shopping around for a bat house, you need to be very careful. Don't purchase a bat house solely based on the price. Many are poorly constructed of cheap material that will deteriorate rapidly, and they may not even meet bat needs. Be sure any house you purchase meets MTBC and BCI standards.
No one builds longer lasting houses, that better meet bat needs, or whose quality is more reasonably priced. Our houses are based on the latest discoveries for improved design. We challenge you to find a better constructed bat house for sale anywhere. We have explained our bat house construction details here.
SUPPORT our TROOPS
We donate a portion of our sales to the "USO"
Thank you for taking the time to review our Certification info.
Phil & Diane Brodak
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More Bat Information:
Buy a Bat House | Bat Facts | About Bats | When to Install a Bat House | Bat House Installation Service | Custom Installation | Paint and Stain | Heat Index Chart | Bat House Construction | Bat House Occupancy | Mounting Brackets | Lifetime Warranty | Bat Removal