Blue Tit & Great Tit Nest Box - Sliding Roof, 28/32 mm Entrance, No Supports

A real nest box for small garden birds (blue tit, great tit, coal tit, tree sparrow), built to the usual nest box guidelines and easy to clean every autumn. Modern Nordic look: a mono-pitch roof and vertical board grooves. The roof slides off for cleaning and there is no metal hinge and no screw to rust.

Bird-friendly sizes

- Inside floor 120 × 120 mm (1.44 dm², 144 cm² of nest space).

- Entrance bottom 150 mm above the inside floor (152 mm with the 28 mm plate): harder for cats and martens to reach the nest from the hole (common guidelines ask for at least 125 mm).

- Inside height 201 mm at the front, 233 mm at the back.

Swappable entrance plate (both sizes included)

- 28 mm: blue tit, coal tit, marsh tit.

- 32 mm: great tit, tree sparrow, nuthatch.

- The plate slides into a slot in the front wall and is locked by the roof. A deep collar makes the entrance a 21 mm tunnel: harder for a paw or a beak to reach in.

- No perch, on purpose. Birds do not need it, and a perch helps cats, magpies and squirrels to get in.

Cleaning without tools

1. Lift the box about 6 cm (it comes free after 55 mm) and take it off the wall plate.

2. Slide the roof back along its rails and lift it off.

3. Empty the old nest (once a year, between October and February), put the roof back and hang the box.

While the box hangs on a wall or a trunk, the roof cannot be opened: the wall stops it after 8 mm, and the side lips hold it down against wind.

Weather

- Roof pitch 15°, roof edge 33 mm in front of the wall and 9 mm above the hole top, drip groove under the edge.

- 10 ventilation slots under the roof, 4 drain holes (6 mm) in the floor.

- Small ribs inside under the entrance help the young birds climb out.

Mounting

A separate wall plate (90 × 136 mm) is fixed with 2 countersunk screws (4-4.5 mm) to a wall, fence post or tree. The box hangs on its dovetail rail and can be taken down in a second.

- Important: the wall, post or trunk must reach at least 7 cm above the top of the wall plate: it is the roof stop. On a short post that ends at the plate the roof is not locked.

- Optional lock against lifting: one short screw (3.5 × 16 mm) from inside the box through the back wall into the wall plate, about 50 mm above the floor and 24 mm left or right of the centre (drill 3 mm).

IN THE FILES

- birdhouse_nest_box-body.stl: the box.

- birdhouse_nest_box-roof.stl: the sliding roof.

- birdhouse_nest_box-wall-mount.stl: the wall plate.

- birdhouse_nest_box-entrance-28.stl and birdhouse_nest_box-entrance-32.stl: the two entrance plates (print the one you need, or both).

- birdhouse_nest_box.scad: the parametric source (entrance size, box size, roof pitch).

SIZE: body 130 × 133 × 237 mm; roof 151 × 166 mm; wall plate 90 × 136 mm; entrance plates 69 × 67 × 21 mm. The body needs a printer with at least 240 mm build height (a 250 mm class machine). It does not fit a 180 mm-high mini printer. The roof, wall plate and plates fit a 170 × 170 mm bed.