Parameters
Style
Classic nesting box: the roof slopes forward so rain runs off the front.
Dimensions
All dimensions are interior (nesting space).
Interior floor width (X axis)
Interior floor depth (Z axis)
Interior height of the front panel — it is lowered slightly so the roof seats flush
Interior height of the back panel — the difference to the front sets the roof slope
Entrance hole
NABU guide values: 26–28 mm blue/coal tit · 32 mm great tit · 34–35 mm sparrow/nuthatch · 45 mm starling
Interior floor to the bottom of the hole — at least 170 mm to keep cats and martens out
Hole for a round dowel below the entrance (0 = none). Note: NABU advises against perches — they also help predators.
Bottom of the entrance hole to the centre of the perch hole
Roof
Front taller (entrance stays in front), rain runs off to the back.
Roof overhang above the front (weather protection for the entrance)
Roof overhang beyond the side walls
Pilot holes in the roof — the roof is screwed on and stays removable for cleaning (0 = none)
Mounting
Floor & drainage
Drain holes in the floor keep the nest dry (NABU recommends 4–5 × 5 mm).
The floor extends forward as a landing board (0 = none); the front wall then plugs into slots in the plate
Material
For outdoors: untreated solid wood or exterior plywood, at least 12 mm
Tool cut width — contours are offset outward by kerf/2
Spacing between parts in the cut layout
Finger joints & layout
Target finger width — 25–35 mm looks right on 12 mm material
Minimum fingers per edge