Best Eastern Bluebird House

Custom Birdhouse Designed Especially for Bluebirds

I designed this with every feature as close as possible to the recommendations of the North American Bluebird Society (NABS), adapted for 3D printing

🏠 Structural Design

• Wall Thickness: 10mm – Sturdy construction ensures protection from predators and elements (insulated from outside temp changes).
• Floor Size: 11 cm x 11 cm floor for cozy nesting. (NABS recommends a floor size of at least 4 inches by 4 inches for eastern bluebirds)
• Roof Thickness: 15mm – Provides extra insulation and durability against harsh weather/sun
• Roof Angle: 10° – Encourages rain runoff while maintaining an open flight path and  maximum interior space for birds.
• No perch: Bluebirds don’t need one, and perches attract invasive species like House Sparrows

🔩 Assembly & Mount

• Magnetic Roof Attachments
  • Holes to embed 6mm x 2 mm Magnets in both the roof and house to secure the roof to the house
  • Secure fit while allowing easy removal for cleaning or monitoring (peak at the eggs/babies!)
• Threaded Inserts for Mounting 
  • Four Holes in rear for M4x10x6 Threaded heat-set Inserts for secure mounting options
  • 4mm reinforced mounting bases provide a solid base without weakening the back wall.
  • Versatile mounting options using M4 screws, including: 
    • Brackets for Pipe Clamp or Zip-Tie Mounting
      • One mounting option is to use the included, durable brackets to hold zip-ties or pipe clamps to the house
      • Rounded edges for even force distribution. 

🕊 Bird-Friendly Entrance & Interior Features

• Optimized Entrance Hole for Eastern Bluebirds
  • Ideal size (55x35mm) to allow Eastern Bluebirds entry while deterring larger birds like starlings or predators
  • Entrance shape designed for Eastern Bluebirds. Some studies showed ellipses are better than round holes; smoothed interior of entrance hole to aid in safe exits for babies
  • The NABS recommended depth from the bottom of the entry hole to the floor of the nest box is between 4½ to 6 inches.
  • Roof overhang clear enough to avoid obstructing entry while maintaining rain protection.
• Kerfs/Interior Ladder (Climbing Ridges) for Nestlings
  • Five evenly spaced interior ridges allow fledglings to grip and climb to the entrance hole
  • Ridges are spaced 15 mm apart for easy footing without obstructing interior space.
  • Kerfs are essential for fledgling safety, making it easier for young birds to leave the nest when ready.

🌬 Ventilation & Drainage

• Side Ventilation Channels with Rain Guard
  • 30 x 9 mm vent slots positioned on the sides near the roofline to allow fresh air
  • Protective baffles deflect rain and avoid water intrusion
  • Ensures fresh air circulation to prevent overheating
• Drainage System
  • Nine 6-mm drain holes in floor with a large, gentle chamfers to encourage drainage and a dry nest 
  • Ensures quick water runoff and prevents mold buildup inside.
• Roof Edges 
  • A slightly rounded front rooftop helps runoff flow
  • A small (2x2mm) underside lip deters water from wicking and blowing back into the house.

🔒 Security & Predator Protection

• Entrance size/shape designed to deter non-Bluebirds
• Thick-Walled Construction
  • Deters predator break-ins and provides insulation from temperature fluctuations.

🎯 Printability

• Easy-to-Print Parts – No extreme overhangs; designed for FDM printing with only one single support
  • Fits in a 220x220x250 print volume
• Print Orientation:
  • House: Upright 
  • Roof: Upside down
  • Mounting Brackets (optional): Flat-side down. 
• Supports:
  • I only supported the top of the entrance ellipse with a tree support (see pic). (I just set slicer to auto tree supports and painted out the supports on the rear mounting holes)
  • I used an automatic brim on both roof and house parts to avoid warping
• Print Time: If you use an abundance of wall perimeters (at least 4), and many ceiling and floor layers (I used 5 each), the print will take a long time--personally, it was my longest print yet, but it will give you a super-strong, solid house.
• Filament/Color: PETG or some other all-weather material. PLA is not recommended for full sunlight. Use light colors to minimize the box overheating during warm weather. I used white PETG (do not use dark colors to avoid UV absorption) 
• I used a 0.40 nozzle, 0.30 layer height, and 10% gyroid infill. I'm sure other options work well too.
• I used CA to glue the magnets to affix the removable roof

This bluebird house combines durability, functionality, and ease of maintenance—ideal for backyard bird lovers who want a low-maintenance, high-performance shelter for their bluebirds! 

Location and mounting tips:

• Location: Open areas with short grass (like yards, fields, or pastures)
• Mount on a pole: Avoid trees or fence posts where predators like raccoons and snakes can easily climb
• Height: Entrance hole should be at least 5 feet above the ground. 
• Use a baffle: A metal or plastic baffle and/or some other anti-critter protection on the pole is recommended to avoid snakes or other predators snacking on the eggs/babies.
• Direction: Face the entrance hole east or southeast to protect from wind and rain
• Spacing: At least 100 meters apart from other bluebird houses to reduce competition
• Monitor for House Sparrows: They allegedly will aggressively take over bluebird houses.