How To Make a Barn Owl Box (Step-by-Step)

Barn Owls are notorious rodent hunters, making them the perfect companion if you live on a farm or out in the countryside.

One sure-fire way to encourage them to make your home their own is to provide them with a Barn Owl nesting box. Luckily, they’re pretty easy to make from scratch.

Here’s a step-by-step guide on how you can make a barn owl box:

  1. Cut a sheet of exterior plywood into nine pieces.
  2. Cut a small entrance hole in the front piece of plywood.
  3. Cut grip grooves under the entrance hole. 
  4. Drill drainage holes into the bottom piece of plywood.
  5. Drill air holes into the top piece of plywood.
  6. Drill holes into the plywood to prepare for screws.
  7. Assemble the box, joining sides with screws.
  8. Coat the joints with wood glue or plastic resin.
  9. Prepare the box for time spent in direct sunlight.
  10. Place the box away from roads and people.
  11. Mount the nesting box on a flat surface.

1. Cut a Sheet of Exterior Plywood Into Nine Pieces

To begin with, you need to ensure you have weatherproof plywood, which will hold up to being left in the rain and direct sunlight.

This is known as exterior plywood or marine-grade plywood.

You’ll need a ¾ x 48 x 96 inch (1.91 x 121.92 x 243.84 cm) piece of plywood or siding, which you’ll cut into nine pieces as follows:

Separate PiecesIn InchesIn Centimeters
Upper Right Side11  x 12 ⅜ inch27.94 x 31.43 cm
Clean-Out Door (bottom right)5 x 12 ⅜ inch12.7 x 31.43 cm
Left Side16 x 12 ⅜ inch40.64 x 31.43 cm
Front22 ¾ x 16 inch55.88 x 40.64 cm
Back22 ¾ x 16 inch55.88 x 40.64 cm
Top7 ½ x 12 ⅜ inch17.78 x 31.43 cm
Top Door16 ¾ x 12 ⅜ inch40.64 x 31.43 cm
Bottom10 ⅞ x 22 ¾ inch25.4 x 55.88 cm
Divider5 ½ x 15 ¼ inch12.7 x 38.1 cm

2. Cut a Small Entrance Hole in the Front Piece of Plywood

You need to cut a hole big enough for the owl to get inside but small enough to keep away predators.

Aim for about five inches wide (12.7 cm), two inches (5.08 cm) from the top of the box.

Cutting this hole in an ellipse shape will keep predators from being able to easily reach inside. 

3. Cut Grip Grooves Under the Entrance Hole

Cutting grooves into the plywood beneath the opening gives the owls something to grip onto when they’re entering and exiting the box. 

However, be careful not to cut too deeply into the wood, as you run the risk of puncturing a hole all the way to the other side.

This will slowly weaken over time and eventually split.

Create these grooves with either a sharp chisel or a router with a straight bit.

4. Drill Drainage Holes Into the Bottom Piece of Plywood

There should be about eight to twelve drainage holes in the bottom piece of plywood, each about ½ inch (1.27 cm) wide. These prevent moisture from accumulating in the box. 

This can be done with a drill before any of the parts are assembled.

5. Drill Air Holes Into the Top Piece of Plywood

To allow for air circulation, drill holes into the top piece of plywood or in the side pieces of plywood near the top.

These should be near the corners of the box to allow for optimal airflow. 

These holes should be very similar to the drainage holes drilled into the bottom piece of plywood, and, again, you should do this before assembling the box.

6. Drill Holes Into the Plywood To Prepare for Screws

Drill holes everywhere that you’ll need to join two pieces together when assembling.

Remember that you can’t really overdo this, so add as many as you think you’ll need to ensure the structure is strong.

For a visual representation of where to place these holes, see the Barn Owl box building guide from Charles G. Wade, Lee Pauser, and David Altknecht.

7. Assemble the Box, Joining Sides With Screws

Use two-inch (5.08 cm) deck screws to join the sides of the box together. Ensure that you leave a one-inch (2.54 cm) ventilation gap between pieces across from the main opening. 

When forming the top and side, which have door pieces, screw a metal hinge into place, attaching the top to the top door and the side to the clean-out door. 

8. Coat the Joints With Wood Glue or Plastic Resin

For extra durability, coat the joints of the wooden box with wood glue made for exterior surfaces or a marine-grade plastic resin.

This will ensure that the box does not split apart over time. 

Some owl box builders choose to use only wood glue or resin and not screws, but most use both for a combination of mechanical and adhesive strength.

9. Prepare the Box for Time Spent in Direct Sunlight

If your box will be placed in direct sunlight or situated in an environment where temperatures exceed 85°F (29.4°C), you need to treat the box to make it heat resistant.

To do this, add a coat of white paint to the outside. You can also paint an extra sheet of plywood white and situated it on top of the box as a sun shield. 

If you choose to use a separate sun shield, make sure you leave a two-inch (5.08 cm) insulating gap between the shield and the box.

10. Place the Box Away From Roads and People

Barn Owl boxes should be kept away from roads and other sources of human activity. 

The best location is somewhere where there’s plenty of food; many farmers choose to place Barn Owl boxes in areas infested with rodents. 

If you’re placing multiple boxes, make sure that you allow 640 acres of space (258.99 ha) for each box. 

The tree should be within 100 yards (91.44 m) of a large tree, like an oak or a sycamore. This will protect the owl and the box. 

11. Mount the Nesting Box on a Flat Surface

To mount your nesting box, push threaded bolts through the box and into the mounting surface, whether a wooden pole, platform or tree.

Make sure that no bolts are protruding into the box, as this can injure the owls. 

Wherever you mount your nesting box, ensure that you can open both the top door and the clean-out door at the bottom without too much friction and without causing damage. 

Final Thoughts

If you live on a farm (or near one), chances are you’ve experienced some sort of rodents on your land.

If it’s becoming a bigger problem, encouraging Barn Owls to nest on your property is a natural way to help control the rodent and small animal population.

The best time of year to install an owl box is in January or February when they’re looking to nest.

Be sure to keep the box clear of roads and foot traffic and allow for plenty of space should you need more than one.