This wren bird house design is compatible with not only wrens, but other bird species as well. The interior size of the nest box and the entrance hole make it an ideal home for a variety of small nesting birds.
This bird house can be built from 20" of 1x4, 14" of 1x8 and 20" of 1x6 cedar fence boards or planks.
Using the drawings below for specifications, cut the front piece from the 14" 1x8 and use it as a template for the back piece. On the front piece, measure up from the bottom 3 1/4" and make a mark. This mark will be the bottom of the 1 1/4" entrance hole.
Drill the 1 1/4" entrance hole with a paddle bit.
Cut the two side pieces and the bottom piece as indicated in the drawings below and above (left).
Using 16 gauge 2" air nails, attach the front and back pieces to the left side and bottom as indicated in the drawings below. Using 1 1/4" galvanized wood screws as a hinge, attach the right side piece so that it can be used as an access hatch to clean out old nesting materials.
From the 1x6, cut the two roof sections (9 1/2" x 5 3/4") and attach them as shown in the drawings above and below. Overhang the roof approximately 1 1/2" - 2" above the entrance hole.
Finally, add the 3/4" x 3/4" x 11 1/2" mounting bar to the top of the bird house. Center it so that it hangs 1" past the roof on both ends. Use wire to loop through the parts that extend past the front and back of the roof to hang the bird house.