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Bat House Plans & Dimensions: Complete Build Guide
Free printable cut list and dimensioned plans for a single-chamber bat house, built to Bat Conservation International specifications — plus exactly where to mount it, what colour to paint it, and the reasons most bat houses sit empty for years.
A single little brown bat eats over a thousand mosquitoes an hour. A nursing female eats close to her own body weight in insects every night. And across North America they are running out of places to sleep — the hollow trees, barns and rock faces they have used for generations are disappearing.
A bat house fixes that, but only if it is built right. Chamber depth, height, sun exposure and colour decide whether bats move in within days or ignore it for years. This guide gives you the full plans and the placement rules together, because one without the other does not work.
On this page
Bat House Plans — Cut List & Dimensions
This is the standard single-chamber design, sized so the whole thing comes out of a quarter sheet of plywood with three straight cuts. It holds 50 to 150 bats and is the right first build.
Single-Chamber Bat House
Materials
| Item | Spec | Qty |
|---|---|---|
| Plywood | ½" AC, BC or T1-11 exterior grade — quarter sheet, 2ft × 4ft | 1 |
| Furring strip | 1×2 pine or cedar, 8 ft (finished ¾" × 1¾") | 1 |
| Mesh | ⅛" HDPE plastic netting, cut to 20" × 22½" | 1 |
| Screws | 1⅝" exterior / multipurpose | 20–30 |
| Caulk | Paintable exterior acrylic | 1 tube |
| Paint | Exterior water-based latex — colour by climate (see below) | 1 pint |
| Staples | 5/16" for the mesh | 1 box |
Cut list
| Piece | Cut from | Dimensions | Qty |
|---|---|---|---|
| Back panel | Plywood | 26½" × 24" | 1 |
| Front panel — top | Plywood | 16½" × 24" | 1 |
| Front panel — bottom | Plywood | 5" × 24" | 1 |
| Top spacer | Furring strip | 24" | 1 |
| Side spacers | Furring strip | 20½" | 2 |
| Roof (optional) | Plywood offcut | 24" × 5–6", angled 30–45° | 1 |
Ask the lumberyard to make the three plywood cuts — most will do it free, and the panels come out square.
Assembly
- Roughen the interior. On the inside face of the back panel and the landing area below it, cut horizontal grooves 1/32" to 1/16" deep, spaced ¼" to ½" apart. Or staple the HDPE mesh over the same area. Bats cannot climb smooth plywood.
- Stain the interior dark. Two coats of dark water-based stain on the inside surfaces. Never paint the interior — paint fills the grooves you just cut.
- Cut the furring strip into one 24" piece and two 20½" pieces.
- Caulk and fit the spacers. Run the 24" strip flat across the top of the back panel, then the two 20½" strips down each side. Their ¾" thickness is what creates the roost chamber — this is the measurement that matters most.
- Attach the top front panel (16½") to the spacers with 1⅝" screws, caulking the joints first.
- Attach the bottom front panel (5"), leaving a ½" vent gap between the two front pieces. The vent stops the chamber overheating in summer.
- Caulk every exterior seam, especially along the top. Water getting into the chamber is the fastest way to lose a colony.
- Fit the roof at a 30–45° slope with a slight overhang. Optional, strongly recommended, and it adds years to the life of the house.
- Paint the exterior — three coats, colour chosen for your climate. Let it cure fully outdoors before mounting.
Plans adapted from Bat Conservation International's published single-chamber design. Free to print and share. — privatelandswildlife.com
The chamber must be ¾ of an inch. Not half an inch, not an inch and a half. Bats are crevice animals — they wedge into gaps just wide enough to grip both walls at once. Build it wider and they will not use it, no matter how good the placement is. This one number decides more than everything else on this page combined.
What Colour to Paint It
Exterior colour controls how hot the chamber gets, and a nursing colony needs interior temperatures of 80–100°F. Get the colour wrong for your latitude and the house either never warms up or cooks.
| Climate | Average summer high | Colour |
|---|---|---|
| Northern states | Below 85°F | Black |
| Middle states | 85–95°F | Dark brown or grey |
| Southern states | Above 95°F | Medium brown or tan |
| Desert Southwest | Above 100°F | Light grey or tan |
Here in mid-Michigan we paint ours black. Summers rarely push past the mid-eighties and the chamber needs all the heat it can absorb to hold temperature through a cool night in June.
Where to Mount It
Placement decides as much as construction. A perfect bat house in a bad spot stays empty. Four things matter.
Sun — 6 to 8 hours
South or south-east facing, direct sun. The chamber has to reach 80–100°F for a maternity colony.
Height — 12 ft minimum
15 to 20 feet is ideal. Keeps it clear of predators and gives bats room to drop into flight on exit.
Water within ¼ mile
Pond, stream, lake or wetland. Bats drink on the wing and won't settle far from water.
Clear drop below
At least 20 feet of open air beneath and in front. Bats fall to gain speed — they can't take off from a standstill.
| Mounting location | Rating | Why |
|---|---|---|
| Dedicated pole or post | Best | Full control of sun orientation, no branch shade, easy to site near water |
| Building — south or east wall | Excellent | Walls hold heat well. Avoid anywhere with foot traffic underneath. |
| Tree trunk, open exposure | Fair | Only if there's almost no canopy above. Most trees shade too much. |
| Tree with full canopy | Poor | Never gets warm enough. Very rarely colonised. |
Mount two houses back to back on one pole — one facing south, one facing east or west. The bats then choose their temperature: cooler side on hot days, warmer side on cool ones. Dual-mounted pairs get colonised faster and hold larger colonies than any single house.
What to avoid
- Bright lights nearby — lights draw insects, but they also draw owls and hawks that learn to hunt there.
- Under a roof overhang — kills the sun exposure and blocks the flight approach.
- Near active wasp nests — wasps take over empty bat houses and are almost impossible to shift once settled.
- North-facing — never reaches maternity-colony temperature.
- Below 12 feet — predation risk climbs sharply and colonisation rates collapse.
Why Bats Aren't Using Your Bat House
Give it time first — even a well-sited house can take two seasons to find. But if it has been up more than two summers with nothing, one of these is almost certainly why.
| Problem | Fix |
|---|---|
| Under 6 hours of sun | Move it to a south or south-east face with no shade |
| Mounted under 12 feet | Remount at 15–20 feet |
| No water within ¼ mile | Relocate the house — or build a pond |
| Interior too smooth | Add mesh or cut horizontal grooves |
| Wasps moved in | Clear nests in late autumn or winter when bats are gone |
| Chamber wrong width | Nothing to do but rebuild — it has to be ¾" |
| Wrong colour for the climate | Repaint using the table above |
| Facing north or shaded | Relocate entirely |
Never use pesticides near a bat house
Insecticides don't just remove the insects bats are hunting — they poison the bats through contaminated prey. A bat eating several hundred treated insects a night accumulates a lethal dose quickly. If you want bats on your land, stopping pesticide use is the single most effective thing you can do. They're doing the pest control for you.
mosquito-sized insects a single little brown bat eats in one hour of feeding
Which Bats Use Bat Houses
Not every species will. Cave bats and the ones that roost in foliage never use them. The species that do are the crevice-roosters — exactly the ones hit hardest by the loss of hollow trees and old barns.
| Species | Range | Colony size | Notes |
|---|---|---|---|
| Little brown bat | Nationwide | 50–200+ | The most common bat house occupant in the US |
| Big brown bat | Nationwide | 20–100 | Larger — wants the wider end of the chamber spacing |
| Mexican free-tailed bat | South & Southwest | Hundreds | Highly colonial — will pack a house tight |
| Evening bat | Southeast & Midwest | 25–100 | Readily takes bat houses in warm climates |
| Yuma myotis | West & Pacific NW | 50–150 | Strong user near water in western states |
| Long-legged myotis | Pacific NW & Rockies | 20–80 | Common western occupant |
White-nose syndrome has killed over six million bats in eastern North America since 2006, and some cave colonies are down by ninety percent or more. Habitat loss compounds it. A bat house doesn't cure the disease, but it gives a surviving colony somewhere to raise pups.
Buying Instead of Building
A bought house works fine — provided the specifications are right. Most of the ones sold in garden centres are not.
Most cheap bat houses never get used
Under two feet tall, chambers the wrong width, and materials that can't hold temperature. A house shorter than 24 inches with chambers anything other than about ¾ of an inch will sit empty regardless of where you put it. If you're buying, check the chamber depth before anything else — and if the listing doesn't state it, that tells you what you need to know.
Checklist before you buy
- At least 24 inches tall — taller is better
- Chamber depth of ¾ inch
- Rough interior — grooved wood or mesh already fitted
- Solid roof with an overhang
- Untreated or bat-safe wood — never pressure-treated inside the chamber
- Landing area of at least 3 inches below the entrance
- Built to Bat Conservation International specifications
Bat Houses Through the Seasons
Spring · Mar–May
Bats emerge and scouts check new roosts. The best window to have a house already up. Maternity colonies form in April and May.
Summer · Jun–Aug
Peak occupancy. Pups born June to July, flying by three or four weeks. Do not disturb the house at all during this period.
Autumn · Sep–Nov
Colonies break up and migrants head south. Once they've gone, this is the time to clean and inspect.
Winter · Dec–Feb
Empty. Recaulk any opened seams, re-roughen smooth interior surfaces, and mount new houses ready for spring.
Common Questions
What are the dimensions of a bat house?
A single-chamber bat house should be at least 24 inches tall and 16 to 24 inches wide, with a roost chamber ¾ of an inch deep and a landing area of 3 to 6 inches below the entrance. The plans on this page use a 26½" × 24" back panel, a 16½" and a 5" front panel with a ½" vent gap between them, and ¾" furring strips to set the chamber.
How deep should a bat house chamber be?
Three quarters of an inch. Bats are crevice-roosting animals and wedge into gaps narrow enough to grip both walls at once. A chamber much wider than ¾" will generally be ignored, and a narrower one they cannot enter.
What wood should I use for a bat house?
Half-inch exterior-grade plywood (AC, BC or T1-11) for the panels, with pine or cedar furring strips. Cedar lasts longest untreated. Never use pressure-treated lumber anywhere the bats will contact — the preservatives are toxic in an enclosed chamber.
How high should a bat house be mounted?
Twelve feet minimum, 15 to 20 feet ideally. Height keeps it away from ground predators and gives the bats the open air they need below the house — they drop to gain flying speed rather than taking off from rest.
What colour should I paint a bat house?
It depends on your latitude. Black in northern states where summers stay below 85°F, dark brown or grey through the middle of the country, medium brown or tan in the south, and light grey or tan in the desert southwest where overheating is the real risk.
How long before bats move in?
Anywhere from days to two full seasons. In a good spot during spring scouting they can find it almost immediately. If a house has been up more than two summers with no sign of use, something about the placement or the build is wrong — work through the troubleshooting table above.
Will a bat house attract bats into my house?
The opposite. A well-placed bat house gives them somewhere better to roost than your attic or wall voids, and it is one of the standard tools for getting bats out of buildings while keeping them on the property.
Can I mount a bat house on a tree?
You can, but results are poor. Most trees shade the house enough that it never reaches the 80–100°F a maternity colony needs. A dedicated pole consistently outperforms tree mounts.
Keep Reading
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The full diet — and why a colony is worth more than any pesticide.
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The Whispering Woods
A children's book about a girl named Elara, a puppy named Scout, and the forest animals they meet — written on the same 30 acres of Michigan habitat these guides come from.
See the bookPrivate Lands Wildlife is a 501(c)(3) wildlife habitat nonprofit in Gratiot County, Michigan. Plans adapted from Bat Conservation International's published single-chamber design. Bats are protected in many states — check your local regulations before removing or excluding an existing colony.