How To Build A Shade Arbor

We spent the first weekend cutting the lumber to length and applying two coats of primer to all surfaces. The next weekend, we dug and poured concrete footings and applied two topcoats of paint to the parts. Then we took one more day to build the arbor and paint the posts, which arrived the day before construction began. The arbor was built entirely of construction-grade redwood, which resists rot and insects. Although cedar and pressure-treated pine are also rot- and insect-resistant, redwood is friendlier to work with. It’s lightweight, soft and very easy to cut and shape. It’s also less likely than pressure-treated pine to warp or twist, and it holds paint beautifully. The total cost for the redwood was about $1,500. Western red cedar costs about the same. If you’re willing to sacrifice some dimensional stability, use pressure-treated pine, which runs significantly less—just about $600 to $700.

Step 1: Dig footing holes

Dig each footing hole about 18-inches-wide and 24-inches-deep, or to the frost line, whichever depth is greater. Fill each hole with concrete, then insert a 42-inch-long piece of ½-inch-diameter galvanized-metal pipe. (The pipe has an outside diameter of 1 ½ inches) Leave 18-inches of pipe sticking up from the middle of the footing. Allow the concrete to cure at least 24 hours. Next, use a long, 1 ½-inch-diameter auger bit or spade bit to bore a center hole into the bottom end of a post.

Step 2: Treat and lift the posts

Treat the end of the post with wood preservative. Then lift up the post and have a helper align the center hole with the pipe. Slowly lower the post over the pipe until it sits on the concrete footing. Do the same for the remaining five posts. Check to be sure that each post is perfectly plumb; if necessary, drive a cedar-shingle shim underneath to align it.

Step 3: Assemble 2x8 beams

Assemble the three pairs of double 2x8 beams before lifting them onto the top of the posts. For each pair, cut two 7½-inch-square pieces of ½-inch-thick pressure-treated plywood. Screw the plywood plates to the bottom edge of two 2x8s with galvanized decking screws. Carefully position the plywood plates so they align with the posts.

Step 4: Raise and secure the beam

Raise the assembled beam with a helper and place it on top of the posts. To secure the beam, drive screws down through the plywood plates and into the tops of the posts.

Step 5: Lay the rafters

Lay the 17½-foot-long rafters across the 2x8 beams, spacing them 20-inches on center. Attach each rafter with 3½-inch decking screws driven down at an angle into the 2x8s. Place screws alternately on one side of the rafter and then the other to hold each one straight up on edge.

Step 6: Lay the lattice strips

Next, lay the nine 1x2 lattice strips across the 2x6 rafters; space them 21½-inches on center. Use a tape measure to ensure that each 10½-foot-long lattice strip overhangs the first rafter by 2-inches.

Step 7: Fasten the lattice

Fasten the lattice strips to the rafters with 2½-inch decking screws.

Step 8: Hide the fastening plates

After finishing the overhead canopy, install 1x3 trim around the top of each post to hide the plywood fastening plates. Attach the trim with galvanized finishing nails.

Step 9: Finish the post corners

Use a router fitted with a ½-inch chamfering bit to shape all four corners of each post. Make two or three progressively deeper cuts so you don’t splinter the wood or overload the tool. Start the chamfers 3-inches below the 1x3 trim and end them 20-inches above the bottom of the posts. Sand the chamfers smooth with a random-orbit sander, then prime and paint them to match the rest of the structure.

Tools