Bat house placement: sun, height, color and clearance explained

You can buy the best bat house in the country and still end up with an empty box if you put it in the wrong place. Bats are choosy about temperature, sunlight, height and flight space. The numbers below follow guidance from Bat Conservation International (BCI), the best-known source on bat houses in North America. When you want to test a specific location, try our bat house checker.

Step 1: know your July average high

Temperature drives almost every other choice. Look up the average daily high for July in your town, which you can find in the National Weather Service's climate normals or from your state climatologist. This number tells you how much sun your house needs and what color it should be.

Step 2: sun hours

Bats use roosts that are warm. BCI recommends:

• At least 6 hours of direct sun where July average highs are below 100°F.
• 10 or more hours where July average highs are 80°F or lower, since cool climates need more heat.
• Special care above 100°F. Where July highs reach or exceed 100°F, houses can overheat, so seek regional BCI guidance, favor lighter color, tall multi-chamber houses with good ventilation and some afternoon shade where advised.

To measure sun hours, watch the site on a clear summer day, or take photos every hour or so from sunrise to sunset. Remember that trees and buildings cast shadows that move over the day, and that summer sun angles differ from spring ones.

Step 3: color

Choose the color from your July average high. These are the common BCI-style recommendations:

Apply water-based, exterior-grade stain or paint to the outside only. Do not paint the inside or the landing area. Check that the finish is not strongly scented, and let it air out.

Step 4: height, mount and clearance

• Height. Mount at least 12 feet above the ground. Fifteen to twenty feet is better, because bats need to drop down from the entrance to gain speed, and height keeps predators away.
• Pole or building. Mounting on a tree is discouraged, because trees shade the house, the wind sways it, and predators can climb to it. Metal siding can overheat and is hard for bats to grip. Wood, brick or stone walls and sturdy poles work well.
• Clearance. Keep 20 to 25 feet of open space below and around the entrance, free of branches, wires and other obstacles.
• Away from lights. Bright outdoor lights interfere with bats and draw insects to the wrong place. Mount the house away from them where possible.

On the open Plains, a pole is often the best choice because buildings and trees are scarce. Use a sturdy post, set it deeply and brace it for wind. Follow the instructions that came with the house for exact hardware.

Step 5: water and surroundings

Bats are most likely to use houses near water, such as a stream, pond, lake or wetland, within about a quarter mile. Surrounding habitat matters too. Mixed fields, woodland edges, native plantings and open water offer more insects, while sprayed lawns offer fewer. If nearby bats roost in trees or buildings, a house offers an additional option. Ask your state wildlife agency whether bat species in your area use houses.

Step 6: choose the right house

• Chambers. At least two, and ideally three or four, give bats a range of temperatures.
• Roost spacing. About 3/4 to 1 inch between partitions.
• Rough interior surface. Grooves or mesh let bats grip.
• Ventilation and a landing area. Look for a platform below the chambers and adequate vent slots, especially in warm regions.
• Size. Taller and wider houses hold temperature better.

Step 7: timing

Install the house before bats return in spring. If you miss that window, install it anyway, since bats can move in later, and it is better to have it ready for next year. There is no reliable timeframe for occupancy. Some houses fill in the first season, while others take several years.

A worked example

Suppose you live in Kansas, where the July average high is about 90°F. You have a sunny, south-facing wall of a shed that is 14 feet tall to the eaves, with water 300 yards away and a clear path below. Under the guidance above:

• Sun: You measure 8 hours of direct sun, which is above the 6-hour minimum.
• Color: At 85 to 95°F, choose dark brown or dark gray.
• Height: 12 feet minimum, so mounting at 13 or 14 feet works, but higher is better.
• Clearance: Check that no branches or wires intrude within 20 to 25 feet.
• Water: 300 yards is a little under a quarter mile, so that is a good sign.
• Chambers: Pick a house with at least two, preferably three.

This site checks every box. You could run the same numbers in the checker.

Safety around bat houses

Never touch a bat with bare hands. If a bat bites or scratches someone, or is found in a room where people or pets were sleeping, call your local health department. Wear a dust mask and gloves when cleaning below a house.