Before you start
- Read the complete cut list and dry-fit the assembly before fastening. Wear eye and hearing protection and control wood dust.
- Use untreated wood with rough roosting surfaces. Leave interiors and exposed landing surfaces unpainted; do not add plastic mesh.
- Choose exterior water-based finish shade for the local summer climate. Provide shade or a suitable alternative roost where overheating is possible.
- Plan at least 12 ft of clear space below the entrance and a clear flight path. Confirm access, mounting support and maintenance access before building.
Dimensions and opening sizes
- Panel width
- 24 in
- Back height
- 26 1/2 in
- Front height
- 21 1/2 in
- Roost gap
- 3/4 in
Shopping list
| Buy | Material | Stock size |
|---|---|---|
| 1 piece | Exterior plywood, untreated | 1/2 in x 48 x 96 in |
| 1 piece | Untreated fir | 1x2 x 8 ft |
| 2 pieces | Untreated cedar | 1x4 x 8 ft |
| 1 piece | Exterior wood screws | No. 8 x 1 1/4 in, box of 100 |
| 1 piece | Exterior wood screws | No. 8 x 1 3/4 in, box of 25 |
| 1 piece | Exterior paintable sealant | 10 oz cartridge |
| 1 piece | Exterior water-based primer and finish | 1 quart finish plus primer per label |
| 1 piece | Corrosion-resistant roof flashing | 28 x 6 in blank, formed to fit |
Quantity notes
One complete configuration, with stock allocation and allowance for saw kerf. Unused stock remains for other projects.
- Exterior plywood, untreated, 1/2 in x 48 x 96 in: Full sheet allows kerf. Follow the layout; source fractional-sheet quantities do not allow cuts as written.
- Untreated fir, 1x2 x 8 ft: Actual 3/4 x 1 1/2. Small:24 +20 +20. Large board 1:43 1/2 +24; board 2:43 1/2.
- Untreated cedar, 1x4 x 8 ft: Small board 1:30+30+17; board 2:26. Large board 1:58+26; board 2:58+17. All include kerf.
- Exterior wood screws, No. 8 x 1 1/4 in, box of 100: Plywood to furring and rear closure; keep tips flush or recessed.
- Exterior wood screws, No. 8 x 1 3/4 in, box of 25: Rails through plywood into furring, and roof.
- Exterior water-based primer and finish, 1 quart finish plus primer per label: Exterior only; choose shade for summer climate.
- Corrosion-resistant roof flashing, 28 x 6 in blank, formed to fit: Bend to cover cap and shed water over edges; protect cut edges.
Required installation supplies
- Choose four building anchors and any blocking for the actual wall, rail holes, wind exposure and house weight; anchor capacity is not specified by the source.
Tools & equipment
- Saw with rip guide and bevel adjustment
- Drill, bits, countersink and screw driver
- Tape measure, square, clamps and 3/4 in spacing gauge
- Rasp or coarse scraper; eye, hearing and dust protection
- Site-appropriate access and lifting equipment
BEFORE YOU BUILD
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Instructions
01 Cut the panels and strips
- Cut the back 24 x 26 1/2 and front 24 x 21 1/2 from 1/2 in exterior plywood. Keep the 24 in edges horizontal.
- Cut one 24 in top furring strip and two 20 in side strips from actual 3/4 x 1 1/2 stock.
- Cut two 30 in rails, one 17 in rear closure and one 26 in roof from actual 3/4 x 3 1/2 stock. Use the board allocations in the shopping list.
Check: Check every part against the cut list before assembly.
02 Roughen the roosting faces
- Roughen both faces of the back and the inside of the front with shallow horizontal scratches or rough-sawn texture. Do not weaken the 1/2 in panels with deep cuts.
- Remove loose splinters; leave enough tooth for claws. Keep the front exterior smooth.
- Leave the interior and landing area bare. Select any climate-specific ventilation changes before assembly with local bat-house guidance. This CAD model has no added vent holes.
Check: All surfaces accessible to bats have secure, splinter-free grip.
03 Attach the furring
- Lay the back flat with its inside face up. Set the 24 in strip flush with the top edge and the side strips flush with the side edges, ending 5 above the bottom.
- Run a thin bead of sealant under each strip. Clamp square. Predrill and fasten from the back with 1 1/4 in exterior screws at about 6 in spacing; keep screws at least 3/4 in from strip ends.
- Keep the bottom open. Measure the strip thickness at several places to verify the 3/4 in chamber.
Check: Top and side strips meet without gaps; lower ends align with the future front bottom.
04 Fasten the front
- Apply sealant to the exposed furring faces. Lay the front flush with the top and side edges of the back.
- Predrill and drive 1 1/4 in screws through the front into the strips at about 6 in spacing. Offset these holes from screws entering from the back.
- Wipe away squeeze-out and check the bottom opening for projecting screw points.
Check: The front ends 5 in above the back bottom; the open slot stays 3/4 in deep.
05 Attach the rear rails
- Center each 30 in rail vertically on the back, flush with the left or right edge. Each end projects 1 3/4 in beyond the plywood.
- Predrill through each rail and the plywood into the side furring. Use four 1 3/4 in screws per rail, evenly spaced within the front-covered portion; stagger them from existing screws.
- Fit the 17 in closure between rails with its upper edge flush with the plywood top. Seal its upper seam. Predrill from the rear through the closure into the plywood and use 1 1/4 in screws with their heads flush; do not countersink into the closure or let tips project through the inside face.
Check: Rails are parallel; rear top closure fits exactly between the 3 1/2 in rails.
06 Fit the roof and seal the shell
- Center the 26 in roof across the 24 in box. Set its rear edge against the front faces of the rails; the front overhang is 1 3/4 in.
- Predrill and fasten down through the cap into the top furring with four 1 3/4 in screws. Keep their centers over the 3/4 in furring thickness.
- Fit folded flashing over the cap with a drip edge and a slight water-shedding fall. Seal the fastener holes and upper seams; keep both lower roost openings clear.
- Prime and finish the exterior according to the finish label. Keep finish out of roosts and off the landing grip; allow full curing before mounting.
Check: Roof sheds water and no sealant, paint or fastener blocks the entry.
07 Mount and inspect the house
- Select four exterior-rated anchors for the building substrate and expected wind load. Use the projecting rail ends to attach the house to structural backing. Keep at least 12 ft clear below its entrance.
- Use appropriate lifting and access equipment. Keep the house vertical, inspect the anchors and confirm the roof drains outward.
- Observe from the ground. Inspect fastening, water entry, warping and thermal exposure regularly without disturbing occupied roosts; repair only when unoccupied.
Check: The mounted house is secure, entry slots are open and landing faces remain rough.
Sources
Functional dimensions informed by the cited Washington Department of Fish and Wildlife woodworking sheet. CAD, instructions, schedules and illustrations authored for DIY Plans.