Drive the Nails
Assemble your walls and front/back pieces in the shape of the house so you can begin attaching them to each other. Before you start nailing away, isolate one sidewall that will become a pivoting doorway. This will allow you to clean out and monitor the nest box. Through this side, you drive only two nails: one each at the top of the front and back pieces. That way, the side door will be anchored at the top so that it can pivot with a little muscle, but you won’t find it swinging in the wind.
Continue nailing from the front and back pieces through the opposite non-pivoting sidewall, leaving gaps of about three inches between each nail. Next, wedge the bottom piece into place and nail from the three non-pivoting sides. Once you have a sturdy, topless birdhouse, use your handsaw to angle the top of the front board to match the downward slope of the two sides. Also, to provide adequate cross ventilation in the box, drill a few small holes near the tops of the two sidewalls. Finally, nail your larger roof board on top (again, skipping the pivoting side), keeping it flush with the birdhouse’s back side and overhanging on the other sides to keep the cavity dry during wet weather.