How to Build a Garden Arbor

Elegant and surprisingly easy to build

Build this garden arbor in a weekend

This combination arbor and swing may look like a challenging, weeks-long project, but it’s not. If you can drive screws and handle a saw, you can build it in a weekend. The swing itself is store-bought, and the arbor that supports it requires only basic skills. Don’t be afraid of those curves and coves; we’ll show you a goof-proof way to cut them.

Time and money

Building and installing the arbor are about two days of work, but you’re best off spreading it over a three-day weekend. You can build it in a day, add a coat of finish the next morning, let it dry overnight and set up the arbor the following day.

The cedar lumber we used cost a few hundred dollars. Pressure-treated lumber would cost about half that. You can spend a C-note on a porch swing or four times that much. Hardware, concrete mix and finish will cost under a hundred.

Figure A: Swing arbor

Use this illustration when building the arbor. Overall dimensions: 107" wide x 87" tall and 40" deep. Note: To print out this illustration, go to Additional Information at the end of this story.

Construction diagram
Figure B: Arch details

Cut the arches out of your 2x12s. Here's how to lay out the cove cuts at the ends.

Cut the ends of the arches this way.

Perfect coves

To kick off this project, cut the beams (B) to length and cove the ends. You don't need skill or experience to cut perfect coves, just a 7-1/4-in. circular saw. Here’s how.

Build the sides

Each side is made from just nine simple parts. Cut them to length following the Cutting List. If you don’t have a miter saw to cut the thick 4x4 beams (B), cut from one side with your circular saw, roll the 4x4 over and cut from the other side. Your cuts won’t line up perfectly, but they’ll be close enough to clean up with a belt sander. The posts (A) don’t need to be cut, as long as they’re approximately 8 ft. long.

Cutting coves in the ends of the beams (B) is easy with a 7-1/4-in. circular saw. Remember to set your saw to full cutting depth before you position the saw. Eyeball the saw blade to center it on the end of the beam; if you’re off by 1/8 in. or so, the cove will still look fine.

Measure from the end of the beam to the mark and make identical marks at each end of both beams. Trace along a square to complete the marks. Clamp down hard on the stop block so it can’t move, and begin cutting. Take your time and make lots of cuts close together. I try to leave only 1/16 in. between cuts. After you break out the remaining wood, sand the cove smooth. The front end of a belt sander is perfect for this, but you can also drag the edge of an orbital sander along the curve or even hand-sand it.

To assemble the sides, start with the rungs (C) and side slats (D). My slats were only about 1-3/8 in. square, so I cut a 2-1/2-in. spacer block to get equal spacing between them. Your slats may be a bit fatter and require a slightly smaller spacer. With the slats/rungs assembled, “toe screw” the rungs to the posts (Photo 1). Driving screws at an angle is a lot easier if you drill pilot holes first to guide the screws. When you screw the beams to the posts, make sure the screw heads sink in flush with the surface so they’re not in the way when you set the arches on them. Bore countersink holes if you have to.

Build the top

The arches (E) are the biggest part of the arbor, but they won’t take any longer to make than the beams. Cut the arch material to length and screw oversize blocks to the ends. Then cut a spring stick to a length of 107-1/2 in. and bend it between the blocks (Photo 2). Almost any flexible material will work as a spring stick. I used a strip of PVC “lumber.” If you use real wood, eyeball the curve—inconsistencies in wood grain can form an arch that’s lopsided or wavy. The width of material needed for the arch is about 10 in., and a 2x12 is 11-1/4 in. wide. That gives you a little leeway to experiment with the positioning of your arch marks to avoid knots.

It’s critical that you make the marks shown in Figure B before you cut out the arches; you’ll need the straight edge of the board to mark the coves and bird’s-mouths (the notches that fit over the beams). The bottom of a 5-gallon bucket is perfect for marking the cove. When all your marks are made, set your circular saw blade depth to 1-3/4 in. and cut the curves (Photo 3). Then cut the coves and bird’s-mouths with a jigsaw.

With the arches cut and sanded, you’re ready to install the top slats (F). As you install the center slat and the cleats, check and double-check to make sure you have the arches spaced correctly. Then make sure the center slat and arches are perpendicular to each other using a square. You may have to nudge the whole assembly to adjust it for squareness. To position the slats quickly—and prevent mistakes—I made a 4-1/4-in.-wide spacer from scrap plywood (Photo 4).

Final assembly and setup

After the sides and top were assembled, I put a coat of exterior stain on them. Staining the top slats was slow and tedious—if I had it to do over again, I’d stain the arches and slats before assembly.

You’ll need a helper to assemble and set up the arbor. Take your time as you brace and square the arbor (Photo 5). Place the horizontal braces 72 in. from the tops of the beams. Then fasten the top by driving screws diagonally through the arches and into the beams. Stand up the arbor exactly where you want it and mark the locations of the postholes. See How to Dig a Posthole for tips on digging postholes.

Additional Information

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