Making Nest Boxes

By Benjamin P. Burtt

BIRD COLUMN FOR December 10 and 24, 2006


1. A Reader’s question: do you still have instructions for making nest boxes for birds? P.E. – Jamesville, NY. This question and the answer appeared in two parts in the Post Standard on the above dates.

Dear P.E.: A custom made box for each species is needed whether you buy or build it. The drawing shows the parts and their measurements for a nest box for each of 7 common small birds which use a box with a 4x4-inch floor.

That same drawing provides the measurements needed to build a box for 5 larger birds that use a floor that is 6x6 inches.

The important measurements are the size of the floor, the diameter of the entrance and the depth of the cavity below the hole.

These measurements are for wood that is 3/4-inches thick.

Fasten the parts with brass screws. Iron nails rust and loosen with time. To add strength and to better seal it against rain you might wish use to use a good exterior glue in the joints before tightening the screws.

To allow the front to pivot, fasten each side to the front with one nail or screw about 1 1/2-inches down from the top. Make certain the nails or screws are positioned exactly the same distance from the top on both sides so the front will pivot properly. Also, make certain the front board has about an 1/8-inch clearance at the top to keep it from binding against the roof when the box is opened. This clearance also provides needed ventilation.

Insert the floor and recess it slightly so the sides and front extend below the floor just a little to prevent water from seeping in.

The roof should be beveled and caulked at the rear so it will fit tightly against the back.

A wood screw at the bottom of the front can be removed to swing the front open for cleaning. The screw passes through a hole or slot in the front and into the floor. Run the grain of the floor side to side to make the screw hold.

Other things to consider

All boxes require ventilation, protection from rain, protection from rotting, placement in a good location and a sturdy mounting that will protect it from predators.


Rain can blow in the entrance or seep through cracks. So bore some 1/4-inch holes in the bottom on a slant so that light does not show through the bottom.

The roof is wider than the box. The joint between the roof and the back should be caulked.


If the nesting box gets too hot in the sun, the young birds will die. The thick wood (3/4-inch) provides insulation, 1/8-inch clearance at the top of the front lets hot air out. A few 1/4-inch holes drilled high on the side under the eaves also can be added.

A weathered, unpainted box is the nearest thing to a natural site. You may wish to protect the wood from rotting especially if it is not made of decay-resistant cedar, redwood or cypress.
If paint is used, select a light shade of brown, green or gray exterior paint and only cover the outside of the box.

One of the simplest and best ways to protect the wood is to paint it with raw linseed oil. Treat the box inside and out and repeat the treatment until the wood is well saturated.

Do not use wood preservative on the inside of the box where the birds might come in contact with it.


A properly constructed box must be put in the right location to make sure the birds will use it. Most species prefer an open, sunny location. Never put the box on a live tree or in the shade.

If you are trying to attract bluebirds, open farmland away from barns or houses where house sparrows are numerous will lessen competition. Short grass appeals to bluebirds for they hunt for insects on the ground.

Fence posts or steel pipes make a good support. Predators, of course, can climb wooden posts or trees better than they can climb steel posts. A smooth metal pipe coated with grease is a very good way to discourage climbers.