Build a Simple Bird Box for Your Garden

By Feeding Birds Responsibly During Cold Spells
Comments 35
24 Aug 2026

Build a Simple Bird Box for Your Garden

Why a nest box is worth an afternoon

A walk round any British garden in spring shows how hard it is for small birds to find somewhere safe to raise young. Old trees with rotten heartwood, gaps behind loose bark, holes in hedge banks — these are the natural cavities that blue tits, great tits, sparrows and nuthatches depend on, and they are in short supply. A plain wooden box fills the gap and costs very little: a length of timber, a handful of screws and an hour or two at the workbench.

Wood is the right material. It breathes, insulates, and holds warmth far better than plastic or ceramic. It also lets you build to the dimensions that suit the birds in your area, which matters far more than any amount of fancy decoration.

The hole is the part that really matters

Everything about a nest box comes down to the entrance hole. Get it wrong and you will either attract nothing at all, or attract the wrong lodger at the expense of the chicks inside. As a rough guide:

25 mm — blue tits and coal tits. Small enough to keep great tits out.
28 mm — great tits, tree sparrows and pied flycatchers in the west and Wales.
32 mm — house sparrows and nuthatches.
45 mm — starlings, which need a larger box as well.

Robins, wrens, song thrushes and spotted flycatchers do not use a hole at all. They want an open-fronted box, with a low front panel so the nest stays sheltered but visible.

And no perch. This is the single most common mistake. A perch below the hole looks kind, but it gives a cat, magpie or grey squirrel somewhere to stand while it hooks a chick — or an incubating adult — out of the nest. A young blue tit can clamber out of the hole on its own; it does not need a step.

What you will need

Use untreated timber about 15 mm thick. Exterior-grade ply is ideal, and offcuts are fine. Cut your panels to these sizes:

Base — 150 mm × 150 mm
Front — 150 mm × 250 mm, with the hole cut so its bottom edge sits about 125 mm above the floor
Back — 150 mm × 320 mm, the extra length letting you screw the box to a tree or fence post
Two sides — 150 mm × 280 mm, with the top edge cut on a slope so the back stands higher than the front
Roof — 220 mm × 200 mm, giving a 50 mm overhang above the hole

You will also want galvanised screws, a drill with a 25–32 mm holesaw depending on your chosen hole size, and either a strip of roofing felt or a spare wooden roof batten. Inside the box, bare wood only. Paint, varnish, stain and preservative are best avoided where birds will be sitting. If you want to protect the outside, use a water-based preservative on the exterior alone and let it dry thoroughly before assembly.

Putting it together

Cut all the panels to size and sand every edge, particularly around the entrance hole.
Drill four or five 5 mm drainage holes in the base, and leave a 2–3 mm gap along the top of each side panel beneath the roof for ventilation.
Screw the front, back and sides to the base, working from the inside so no sharp screw points poke through into the nesting space.
Fit the roof last. Two screws at the back and one at the front lets the lid swing open for cleaning; a detachable side panel works just as well.
Run a finger round the inside. If you would not want to sit on it, sand it again.
If grey squirrels or woodpeckers are about, screw a metal plate around the hole. They will happily enlarge soft timber until the box is useless.

Siting it well

Position matters as much as construction. Aim for somewhere between two and four metres up, out of easy reach of cats and people, and facing between north and east. That keeps the box away from the fiercest midday sun and from the prevailing wet south-westerly winds.

Angle the box very slightly forward so rain runs off the roof rather than trickling down the front and into the hole. Hang it clear of bird tables and feeders, where the constant traffic will stress nesting birds, and make sure there is some cover nearby — a bit of shrubbery or a mature hedge gives fledglings somewhere to hide.

Fix the extended back panel with two screws into a fence post, shed wall or tree trunk, or hang it on a stout nail so you can lift it down easily when autumn comes. Tits are territorial, so keep boxes for the same species a good few metres apart. House sparrows and starlings are colonial, and will happily nest in a cluster.

Put your box up by February if you can, for the earliest nesters, though birds will take to one put up at almost any time of year.

Looking after it through the year

Once the young have flown, usually by September, open the box and empty out the old nest material. Drop it straight in the bin: it will be full of fleas, mites and parasites that would otherwise plague next year's brood. Scald the inside with boiling water, let it dry completely, and never be tempted to use insecticide in a nest box.

Then check the fabric. Has the roof warped? Are the screws still tight? Has the hole been nibbled larger? Finally, remember that birds sometimes roost in boxes on bitter winter nights. If you lift the lid and find a small warm body inside, close it quietly and clean the box during the next mild spell instead.

Then be patient. A new box often sits empty for a season, gets used for roosting through the winter, and only becomes a proper nursery the following spring. Once it does, you will wonder why you waited so long.

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5 Comments

Robert Sonny says Jul 21, 2024 at 10:00am

I must explain to you how all this mistaken idea of denouncing pleasure and praising pain was born and I will give you a complete account of the system
Reply
- John Abraham says Jul 21, 2024 at 10:00am
  
  I must explain to you how all this mistaken idea of denouncing pleasure and praising pain was born and I will give you a complete account of the system
  Reply
  - Robert Sonnysays Jul 21, 2024 at 10:00am
    
    I must explain to you how all this mistaken idea of denouncing pleasure and praising pain was born and I will give you a complete account of the system
    Reply
Robert Sonny says Jul 21, 2024 at 10:00am

I must explain to you how all this mistaken idea of denouncing pleasure and praising pain was born and I will give you a complete account of the system
Reply

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