Bluebird House Plans
Bluebirds nearly vanished from much of North America — and they came back largely because ordinary people put up nest boxes. But a bluebird house only works if the numbers are right. The entrance hole, the floor size, the mounting height, and one thing most people add that they never should. Here are the specs, a complete build, and a free printable plan you can take to the garage.
Bluebird House Dimensions
Bluebird boxes aren't a matter of taste. The dimensions below come from the North American Bluebird Society's long-tested standards, and they exist for hard reasons: the hole size keeps starlings out, the floor size fits a full brood without crowding, and the depth keeps a raccoon's arm from reaching the eggs.
| Specification | Measurement | Why It Matters |
|---|---|---|
| Entrance hole | 1½" diameter (Eastern Bluebird) | Admits bluebirds, excludes starlings |
| Hole (Mountain/Western) | 1 9/16" diameter | Larger birds; still keeps starlings out |
| Floor to bottom of hole | 6 inches | Too shallow and predators reach the nest |
| Interior floor | 4" × 5½" (about 22 sq. in.) | Room for 4–5 nestlings without crowding |
| Top of hole to roof | About 1½" | Keeps the entrance sheltered |
| Wood thickness | ¾" (a standard 1× board) | Insulates against heat and cold |
| Roof overhang | 2" sides, 3"+ front | Sheds rain, blocks reach-in predators |
| Ventilation | Two ½" holes per side, near top | Boxes can cook nestlings in summer heat |
| Drainage | Clipped floor corners | Keeps the nest from sitting in water |
| Perch | None | See below — this one is important |
The Entrance Hole (Get This Exactly Right)
If you get one measurement right, make it this one. The standard 1½-inch round hole for Eastern Bluebirds was set by Dr. Lawrence Zeleny back in 1970, and the logic is simple: it's big enough for a bluebird and too small for a European starling, which would otherwise take the box and kill whatever's inside.
Drill it a quarter-inch too big and you've built a starling box. There's real latitude in almost every other dimension on a bluebird house — there is none here.
Three variations worth knowing:
- 1½" round — the standard for Eastern Bluebirds.
- 1 9/16" round — for Mountain and Western Bluebirds, or anywhere their ranges overlap with Eastern. Research found the larger birds had poor occupancy and worn feathers squeezing through 1½", and the slightly bigger hole still excludes starlings.
- 1⅜" × 2¼" vertical oval — an accepted alternative some builders prefer.
Sand the hole smooth after drilling. Adult bluebirds pass through it hundreds of times a season, and a rough edge wears their feathers.
Never Put a Perch on a Bluebird House
Almost every decorative birdhouse sold in a garden center has a little dowel under the hole. It looks right. It's actively harmful. Bluebirds are cavity nesters — their feet grip wood, and they don't need or want a perch to enter. What a perch does do is give house sparrows and predators a convenient place to sit while they harass the box, and give a sparrow leverage to reach in.
If you're buying a box instead of building one, a perch is the fastest way to spot a decorative product that was never designed for real birds. No perch. Ever.
Materials & Cut List
This whole box comes out of one 1×6 cedar board and a scrap of 1×10 for the roof. Cedar is the classic choice — it weathers beautifully without any finish and resists rot for years. Pine works fine and costs less. Exterior plywood is acceptable.
One absolute rule: never use pressure-treated lumber. The chemicals that preserve it are toxic in an enclosed box full of nestlings.
| Piece | Qty | Dimensions | Notes |
|---|---|---|---|
| Back | 1 | 5½" W × 14" H | Runs long above and below for mounting |
| Front | 1 | 5½" W × 9½" H | 1½" hole, 6" above floor; kerfs inside |
| Sides | 2 | 5½" deep × 10½" H | Two ½" vent holes near the top of each |
| Floor | 1 | 4" W × 5½" D | Recess ¾" up; clip corners for drainage |
| Roof | 1 | 9¼" W × 10" D | From 1×10 — gives 2" side, 3" front overhang |
Also needed: about a dozen 1¼" galvanized deck screws, two 1⅝" screws for the door pivot, one screw or double-headed nail as the latch, a 1½" hole saw or spade bit, a ½" bit for vents, a saw, a drill, and sandpaper.
How to Build It, Step by Step
- Cut your pieces per the list above. Every cut is square — no angled joinery, no jigs, nothing fancy. This is genuinely a beginner build.
- Drill the entrance hole. Center it on the front panel with the bottom of the hole 6" above the floor line. Sand it smooth inside and out.
- Cut the fledgling ladder. Run 4–5 shallow saw kerfs across the inside of the front panel below the hole. Young bluebirds climb these to reach the entrance when it's time to leave. Skip this step on smooth wood and they can be trapped inside — it's the most-missed detail on a homemade box.
- Drill ventilation and drainage. Two ½" holes near the top of each side, angled slightly upward so rain doesn't run in. Clip the four corners off the floor panel for drainage.
- Assemble the box. Attach the floor recessed about ¾" up from the bottom edges (this keeps the end grain out of standing water and adds years to the box). Screw on the back, front, and one fixed side. Pre-drill everything — cedar splits easily.
- Hang the door. The second side pivots on two screws near the top and latches with a single screw at the bottom. This is how you'll monitor and clean, so make it easy to open with one hand.
- Attach the roof with a 2" overhang on the sides and 3" or more in front. That front overhang is real predator protection, not decoration — it stops a raccoon leaning down from above.
- Leave it bare, or finish the outside only. Raw cedar is perfect as-is. If you want to finish it, use linseed oil or a light-colored water-based product on the exterior — never the interior, and never dark colors, which turn the box into an oven.
Where to Put a Bluebird House
A perfectly built box in the wrong place stays empty. Bluebirds hunt insects by watching the ground from a low perch and dropping on them, so they need open country: meadows, pastures, orchards, cemeteries, big mowed lawns — anywhere with short ground cover and a few scattered trees or fence lines to hunt from. They will not use a box in dense woods or a tight suburban lot.
| Factor | What To Do |
|---|---|
| Height | 4–6 feet off the ground — low enough to monitor easily |
| Mount | A smooth metal pole. Not a tree, not a fence post |
| Facing | East is best; north or south next. Avoid west and the prevailing wind |
| View | Entrance facing open ground, ideally with a tree or wire 25–100 ft out |
| Spacing | At least 100 yards between boxes — bluebirds are territorial |
| When to put it up | Late winter (Feb–Mar) before nesting; any time works, they'll find it |
The pairing trick: tree swallows compete with bluebirds for boxes and will fight them for one. But swallows won't tolerate another swallow pair nearby, while they'll happily coexist with bluebirds. So mount two boxes 5–15 feet apart — the swallows take one, defend the area from other swallows, and the bluebirds get the other in peace. You end up hosting both species instead of losing one.
Predator Guards & Poles
This is where most well-meaning bluebird houses fail, and it's worth being blunt about it: a box on a tree or a wooden fence post is a raccoon feeder. Raccoons, snakes, and cats climb wood effortlessly. Every year people put up a beautiful box, watch a pair move in, and then find the nest destroyed — because the box was mounted on the one thing that guarantees predators can reach it.
Mount on a smooth metal pole — electrical conduit, galvanized pipe, or a purpose-made pole — and add a baffle below the box:
- Stovepipe baffle — a length of pipe hung loosely under the box; climbers can't get past the wobble. The proven standard.
- Cone baffle — a wide inverted cone, at least 24" across. Bigger is better.
- Keep it clear — nothing within jumping distance. A branch, fence rail, or brush pile beside the box is a raccoon's launch pad.
Grease and slippery coatings don't work, wash off, and can foul birds' feathers. Use a physical baffle. If you're going to skip anything on this list, don't let it be this.
The House Sparrow Problem
House sparrows are a non-native species, and they are the single biggest threat to nesting bluebirds. They don't just compete for a box — they will enter it, attack the adults, destroy the eggs, and kill nestlings, then build their nest on top. An unmonitored box in an area thick with house sparrows can genuinely be worse than no box at all, because it draws a bluebird pair into a death trap.
The answer isn't to give up, it's to monitor. Check your box weekly through the season and remove house sparrow nests as they appear. Avoid mounting boxes right next to barns, feedlots, and busy feeders where sparrows concentrate. Boxes out in open country away from buildings get far fewer sparrow problems.
An important legal note: house sparrows and European starlings are non-native and are not protected by federal law. Every native bird is. Tree swallows, chickadees, wrens, and titmice may all use your box, and their nests are fully protected — never remove a nest you can't confidently identify. If a native species claims the box, congratulations: put up another one and let them have it.
Monitoring & Cleaning
A bluebird box isn't a decoration you hang and forget — it's a commitment for the season, and it's the fun part. Bluebirds tolerate weekly nest checks well; open the door, take a quick look, close it up.
- Check weekly during nesting season. This is how you catch sparrow trouble, wasps, or a failed nest in time to do something about it.
- Clean out after each brood. Bluebirds often raise two or three broods a season, and they'll re-nest faster in a clean box.
- Final cleanout in fall, then leave the box up all winter — bluebirds huddle inside on cold nights to survive, sometimes a dozen at a time.
- Report your data to NestWatch if you're willing. Nest box monitors are the reason we know what we know about bluebird recovery — your yard becomes real science.
7 Mistakes That Kill a Clutch
- Adding a perch. Hands the box to house sparrows. Never do it.
- Mounting on a tree or wooden post. An open invitation to raccoons and snakes. Metal pole plus baffle, always.
- Skipping the baffle. The pole alone isn't enough. This is the step that most often decides whether the brood survives.
- Using treated lumber. Toxic in a sealed box full of nestlings.
- Drilling the hole oversize. A quarter inch too big turns your bluebird box into a starling box.
- Forgetting the interior kerfs. Fledglings can't climb smooth wood to reach the hole.
- Putting it up and walking away. An unmonitored box in sparrow country can do more harm than good.
Why Nest Boxes Matter More Than Most People Realize
Bluebirds are one of conservation's genuine success stories. Their numbers collapsed through the mid-1900s as old orchards came down, fence posts turned from wood to metal, and starlings and house sparrows took the cavities that were left. What turned it around wasn't policy — it was thousands of ordinary people building boxes and putting them on poles. The bluebird came back because people built it somewhere to live.
That's the whole idea behind the habitat work we do here: dead trees left standing, boxes where the cavities are gone, open ground kept open. A single box on a pole in your yard is a real contribution to that, not a symbolic one.
Frequently Asked Questions
- What size hole does a bluebird house need?
- 1½ inches in diameter for Eastern Bluebirds. Use 1 9/16 inches for Mountain and Western Bluebirds, or where their ranges overlap with Eastern. The hole must not be larger — a bigger opening lets European starlings in, and they will destroy the nest.
- What are the dimensions of a bluebird house?
- An interior floor of about 4" × 5½" (roughly 22 square inches), 6 inches from the floor to the bottom of the entrance hole, ¾" thick untreated wood, a roof overhanging 2" on the sides and 3" in front, and ventilation holes near the top of each side.
- How high should a bluebird house be mounted?
- 4 to 6 feet off the ground, on a smooth metal pole with a predator baffle beneath it. Never mount a bluebird box on a tree or a wooden fence post — raccoons and snakes climb those easily.
- Should a bluebird house have a perch?
- No. Never. Bluebirds are cavity nesters and don't need a perch to enter. A perch only gives house sparrows and predators a place to sit while harassing the box. A perch is the clearest sign a birdhouse was designed as decor rather than for real birds.
- Which direction should a bluebird house face?
- East is best, with north and south next. Avoid facing west, which exposes the box to afternoon heat, and avoid facing into the prevailing wind. Ideally the entrance looks out over open ground with a tree or wire 25–100 feet away for fledglings to fly to.
- What wood should I use for a bluebird house?
- Untreated cedar or pine, ¾ inch thick; exterior plywood also works. Never use pressure-treated lumber — the preservatives are toxic to nestlings. Leave it unfinished, or finish only the outside with linseed oil or a light-colored water-based product.
- How far apart should bluebird houses be?
- At least 100 yards apart, since bluebirds are territorial and won't tolerate another pair close by. The exception is deliberate pairing: two boxes 5–15 feet apart lets a tree swallow pair take one and a bluebird pair the other, since swallows will exclude other swallows but coexist with bluebirds.
- When should I put up a bluebird house?
- Late winter, around February or March, before the nesting season begins. But any time of year works — bluebirds will find a box whenever it goes up, and they'll roost in it through winter for warmth.
- How often should I clean a bluebird house?
- After each brood fledges, since bluebirds often raise two or three broods a season and will re-nest faster in a clean box. Do a final cleanout in the fall, and leave the box up over winter for roosting birds.