4" diameter PVC drain pipe
4" PVC inspection cover
4" PVC end cap
1/2" screw (I use hex head)
1-1/2" screw (again, hex head)
** if you use a 3/4" thick wooden disk as the bottom, instead of the inspection cover you will need instead
- 3/4" thick wooden disk cut to fit the 4" PVC pipe
- 3 1" wood screws
Hex head screw driver for drill
1" hole saw
Crosscut saw (or power saw)
socket for hex head screws
Step 1: The Tube and the Bottom
First, why wrens? They are primarily insect eaters. Plus, I like their song which is loud and complex.
Now to the house. Measure and cut the 4" PVC tube* so you have a 9" long tube. This is the tube or body of the wren house. Make the cut square so the top and bottom will fit securely. Test fit the bottom and top PVC parts. Square off the tube if needed. Temporarily assemble the cap to the tube and drill a 1" entrance hole just below the cap. The 1" hole will let wrens get in but is too small for less desirable birds like sparrows and starlings. Wren don't need a perch. A perch would only give other birds a place to sit to harass the wrens.
Invert the inspection cap (the house bottom) on a piece of scrap wood and drill three 1/4" drainage holes.
*These are often 8-10' long at the DIY store. Buy enough materials for 10-12 houses and give them as gifts.
Step 2: Assembling the Bottom.
This step is best done outside on a sheet of corrugated cardboard since both the PVC primer and cement have a strong, unpleasant odor. Also, keep it off your skin and everything except the target PVC areas.
Following the manufacturer's instructions, apply the PVC primer to the inside of the bottom of the tube and to the mating surface of the PVC bottom. Apply the cement to those two areas and quickly assemble the tube and the bottom. Let the cement cure per the manufacturer's recommendations.
Step 3: Finishing the House
Drill a 1/4" hole directly opposite the entrance hole, in the back of the house. This hole will be used to mount the house.
Drill a pilot hole horizontally through the cover and the tube. Install the 1/2" screw in the hole to secure the cover to the body. This will prevent raccoons from prying the cover off and eating the eggs or young birds.
Step 4: Putting the House Up for Rent
Find a secure location for the wren house. Attach it to a strong wooden post, wall or other site near your home. Trees are OK too but the house should be moved every year or so to allow the tree to grow properly. Try to site the house at least 5' off the ground and away other places where predators could lurk. Drill a pilot hole in the post. Install the screw in the hole in the back of the house, opposite the entrance. I use a hex head screw and screw it into the wood using a socket and ratchet. Firm attachment to a solid base will prevent the house from being blown down or knocked down by predators.
Wrens will almost completely fill the tube with the small twigs they use to build the nest. In the Fall, empty the twigs. If there is damage take the tube to the house for repair. If you attach the tube to a tree, loosen up the attaching screw a turn. Otherwise, tree growth will pop the tube off the tree, leaving the screw in place. It might be a good idea to put a piece of duct tape over the entrance hole to keep mice out. Mark your calendar to remind yourself to remove the tape next Spring.