A birdhouse is one of the best beginner builds you can tackle: it’s small, it uses minimal timber, it finishes quickly, and it actually gets used. A well-built birdhouse made from cedar or pine will last years outdoors and attract small native birds to your garden. This guide walks through a complete build for a small-bird house sized for house sparrows, finches, and similar species — with the entry hole, ventilation, and drainage details that make the difference between a box that birds will actually use and one they’ll ignore.
Why Species-Specific Dimensions Matter
Birds are particular about hole size. The entry hole diameter determines which birds can enter — and more importantly, which predators cannot. For small birds like sparrows, wrens, and finches:
- Entry hole diameter: 38 mm (1.5 inches) — large enough for small birds, small enough to exclude larger predatory birds
- Hole height from floor: 150–180 mm — gives the chicks room to develop before they can reach the opening
- Interior floor size: 100 mm × 100 mm minimum — enough space for a small nest cup
- Interior height: 200–230 mm — sufficient depth below the entry hole
Don’t be tempted to make the hole larger to “let more birds in.” Larger holes invite starlings and other birds that may evict or prey on the smaller birds you’re trying to attract.
Material Choice: Cedar vs Pine
Cedar is the better outdoor timber — it’s naturally rot-resistant, handles temperature swings without warping badly, and doesn’t require a finish to last outdoors. Western red cedar is available at most AU timber yards and specialty hardware stores. If cedar is unavailable or too expensive, untreated pine works fine with an exterior paint or timber oil on the outside surfaces only.
Never use pressure-treated (CCA) timber for a birdhouse. The preservatives — copper, chromium, and arsenic — are toxic to birds. This includes treated pine decking or framing timber. Use untreated pine or cedar only.
Tools Required
- Tape measure, pencil, square
- Circular saw, table saw, or handsaw
- Drill with 38 mm Forstner or spade bit (for entry hole)
- 3 mm drill bit for pilot holes and ventilation holes
- Hammer or nail gun, or drill/driver for screws
- Sandpaper: 80-grit and 120-grit
- Clamps × 2
Materials List
- 1 × 19 × 140 mm cedar DAR (1×6), 1.5 m length — for all panels
- 40 mm exterior screws or galvanised nails × 20
- Wood glue (exterior/weatherproof grade)
- 38 mm Forstner or spade drill bit
- Exterior timber paint or decking oil (for outside only)
- 1 × 50 mm rust-proof hinge (optional, for cleanout roof)
Cut List
All pieces are cut from 19 × 140 mm cedar DAR (or untreated pine DAR). Finished birdhouse exterior: 150 mm wide × 150 mm deep × 280 mm tall at front, with a sloped roof.
| Part Name | Qty | Thickness (mm) | Width (mm) | Length (mm) | Notes |
|---|---|---|---|---|---|
| Front Panel | 1 | 19 | 140 | 280 | 38 mm hole centred, 180 mm from bottom |
| Back Panel | 1 | 19 | 140 | 320 | Taller than front for roof slope; mounting hole at top |
| Left Side Panel | 1 | 19 | 140 | 230 | Top cut at angle to match roof slope |
| Right Side Panel | 1 | 19 | 140 | 230 | Mirror of left side; top cut at angle |
| Floor Panel | 1 | 19 | 102 | 102 | Sits inside walls; 10 mm ripped off each edge for drainage gap |
| Roof Panel | 1 | 19 | 140 | 200 | Overhangs front and sides by 20 mm; hinged or fixed |
Step-by-Step Assembly
Step 1: Cut All Panels
Mark and cut all pieces to length. The side panels require a slight angle cut at the top — about 10–15 degrees — to match the slope of the roof from front to back (the back panel is 40 mm taller than the front). If you have a miter saw, tilt the blade. If not, mark the angle with a bevel gauge and cut with a handsaw.
Step 2: Drill the Entry Hole
On the front panel, measure and mark the centre of the hole: 70 mm from each side edge (centre of the 140 mm width), and 180 mm from the bottom edge. Back the panel with a scrap board and clamp both to your workbench before drilling. Drill slowly — a spade bit can tear out the exit side badly if it breaks through fast. The scrap board behind the panel prevents blowout.
Step 3: Drill Ventilation Holes
Using the 3 mm bit, drill four ventilation holes near the top of each side panel — two holes per side, 10 mm from the top edge, spaced evenly. These allow heat to escape in summer, which is critical: a poorly ventilated birdhouse can reach fatal temperatures on a hot Australian day. The holes are small enough that no predators can exploit them.
Step 4: Prepare the Floor for Drainage
The floor panel is cut slightly smaller than the interior floor area (102 × 102 mm vs 140 mm internal width minus wall thicknesses of 38 mm = 102 mm). This creates a small drainage gap at each corner. Additionally, drill four 6 mm drainage holes through the floor, one near each corner. Standing water in the nest box causes nesting failures and disease.
Step 5: Assemble the Sides to the Back Panel
Apply exterior wood glue to the back edges of the side panels and attach them to the back panel with 40 mm screws. Pre-drill all pilot holes first — you’re always close to an edge or end grain, and splitting is easy in cedar. Check for square before the glue sets.
Step 6: Insert and Secure the Floor
Drop the floor panel into position, resting on the lower edges of the side panels. It should sit about 5 mm up from the very bottom — this is fine, the drainage gaps at the corners are what matter. Apply glue and drive two screws through each side panel into the floor panel edges.
Step 7: Attach the Front Panel
Apply glue to the front edges of the side panels and the exposed front edge of the floor. Bring the front panel into position and clamp. Drive screws through the front into the side panels — two per side — and one screw through the front into each side of the floor. Let the glue cure for at least 30 minutes under clamp pressure before proceeding.
Step 8: Attach the Roof
The simplest roof is a fixed panel glued and screwed across the top, overhanging the front by 20 mm and the sides by 15 mm to shed rain. For annual cleanout (highly recommended — remove old nesting material each season before spring), use a single 50 mm rust-proof hinge at the back to allow the roof to swing open. A small hook-and-eye latch on the front keeps it closed.
Step 9: Finishing
Sand all outer faces to 120-grit and slightly round all outer edges. Paint or oil the exterior surfaces only — do not paint, stain, or treat any interior surfaces, the entry hole edge, or the floor. Birds avoid strong odours and VOCs inside the box. Natural cedar can be left unfinished outdoors; pine should get two coats of exterior paint or decking oil on all outer surfaces.
Step 10: Mounting
Drill a 6 mm mounting hole through the back panel, 40 mm from the top edge. Mount the birdhouse on a post or fence between 1.5 m and 3 m off the ground. Face the entry hole away from prevailing weather (in most of Australia, face east or north-east — away from the afternoon westerlies). Keep it out of direct afternoon sun if possible, and away from branches that give cats a launching platform.
Avoid These Common Mistakes
- No drainage holes in the floor — water accumulation kills chicks
- No ventilation at the top — heat stress kills chicks in AU summers
- Entry hole too large — larger birds will take over or predate the nest
- Painted interior — chemical smell deters birds and may harm nestlings
- Perch below the entry hole — perches actually help predators reach the hole, not the birds inside. Leave them off
- Pressure-treated timber — toxic to birds; use untreated only
A well-built birdhouse is one of those projects that keeps rewarding you — once birds move in, you’ll have a front-row seat to the whole nesting season. If you want to keep building, Ted’s Woodworking has plans for dozens of birdhouse designs alongside 16,000 other woodworking projects — from beginner weekend builds to full furniture suites with complete step-by-step instructions and cut lists.
