Although barn swallows don't seem to mind building a nest in an area that has a lot of human and animal traffic, once their eggs have hatched, the adults become aggressive. They swoop and dive at people that walk under their nests, so you will want to make sure that you place the birdhouse somewhere that you won't constantly be diving for cover. Birdhouses for barn swallows and robins are different from traditional birdhouses in that they aren't enclosed. Barn swallows like to nest in places were they can see what's approaching. Birdhouses for barn swallows need to be built with an open front.
Choose the lumber you want to use for your birdhouse. The best kinds of wood for building birdhouses are pine, poplar, redwood, cedar and spruce.
Cut your lumber into five pieces. You will use these pieces for the back, floor, two sides, and roof of your birdhouse. The sides and floor should be cut into pieces that measure 8 by 8 inches and the back should be 8 inches wide and 12 inches tall. The roof of your birdhouse will measure 8 by 8 inches.
Sand the edges of your newly cut pieces.
Nail the sides and the back to the floor piece. When they are in place, attach the roof.
Mount your barn swallow birdhouse somewhere that is at least 6 feet off the ground and make sure that it is secure and won't fall down when the swallows are trying to raise their new family. Make sure you choose a spot that isn't going to be bothered by cats or raccoons.