Why build a roost box? We’ve had a sparrow roosting above our electrical box at night and, frankly, making a big mess. It gave me an idea. Our birds need a place to perch at night, out of the wind.
I went to the local lumber store and picked up a 1″ x 8″ (real dimensions 3/4″ x 7 3/8″) 8′ foot long piece of cedar (smooth on one side and rough on the other). Here’s a step by step.
I use pocket screws to put the pieces together. You can also insert screws from the back.
Make sure you put the hole in the door at this point. Lee Valley sells birdhouse portal protectors so the squirrels etc. can’t enlarge the hole. They are offered in four diameters to match the preferences of specific cavity-nesting birds: Eastern bluebird (1 1/2″), nuthatch (1 1/4″), chickadee (1 1/8″) and wren (1″). I used their guide to size my entrance hole.
Drill the hole for the door dowel through the side and into the door. Make sure you drill them as straight as possible so the door functions. You can also use a long screw for this.
Here’s what I found in my internet research that might be helpful.