How to Build an Outdoor Sofa

This Old House DIY expert Jenn Largesse shares how to build this handsome three-seater outdoor sofa from 2×4 boards.

by Jenn Largesse, This Old House DIY Expert & Editor, House One

Skill

Easy

Cost

About $165 (not including stain and polyurethane)

Estimated Label

About 4 Hours

Jenn measures seat cushions — Size the seat: To design the sofa, Jenn measures across three bottom cushions, using their exact dimensions to determine the depth and width of the base assembly. | Mock Tuna

There’s no debate that all-weather outdoor furniture and accessories can cost a pretty penny—especially when shopping during the peak spring or summer season. Enter this clean-lined outdoor sofa. Made from inexpensive 2×4 boards, the project requires only a few basic tools. After you cut the lumber to size, pocket-hole joinery makes assembly quick and easy. For the cost of a few cushions—I found mine online for $35 per set (one seat and one back cushion)—and a few hours of work in the shop, you can have this comfortable couch for a fraction of what you’d pay in most stores.

Once assembled, stained, and protected with exterior polyurethane or paint, this sturdy outdoor sofa will let you focus on what matters most— entertaining friends and family—for many summers to come.

Building an Outdoor Sofa: Before You Begin

For this project I hand-selected the best-looking 2×4×8′ boards—sold as “studs”—from my home center. Using dimensional lumber is the most affordable option, but bear in mind that the boards come with rounded edges and grading stamps, so you’ll need to spend some time sanding to transform them into stain-grade stock. If you have access to a workshop, you can run the boards through a thickness planer or use a table saw to remove the rounded edges. You can substitute a naturally weather-resistant wood, such as cedar or cypress, but keep in mind that this would double the cost of the wood used in this project.

Illustration of bench — Peter Sucheski

Cut list

2×4 front legs – 2 @ 28 1/2 inches
2×4 back legs – 2 @ 30 inches
2×4 armrests – 2 @ 23 1/2 inches
2×4 side crosspieces – 6 @ 22 inches
2×4 seat frame – 2 @ 68 inches
2×4 seat slats – 11 @ 22 inches
2×4 backrest boards – 2 @ 68 inches

Steps for Building an Outdoor Sofa

Steps 1 and 2 — Mock Tuna

1. Cut and organize the parts

Following the cut list and cutting diagram, cut the boards to length. (Tip: Using a stop block for making repetitive cuts can save time and improve accuracy.) To facilitate assembly, arrange the parts in four stacks: two sides, base, and back.

2. Drill the pocket holes

After identifying the best, or “show,” face of each board, use a pocket hole jig to drill holes in the back and inside faces where shown in the illustration.

Step 3 and 4 — Mock Tuna

3. Assemble the side frames

With its pocket holes facing inward, position the face of one side’s front leg flush with an armrest’s front end. Apply glue and then drive 2½-inch pocket-hole screws through the leg and into the underside of the armrest. Next, attach the armrest’s face flush to the end of the back leg. Repeat with the opposite side.

4. Add the crosspieces

Place the side frames on your workbench, outside faces down. Next, set the crosspieces on 2×4 blocks between the legs with their pocket holes facing upward. Attach the crosspieces to the legs where shown.

Step 5 and 6 — Mock Tuna

5. Assemble the seat

Position the two seat rails on a work surface with their pocket holes facing in the same direction. Arrange the slats between the rails about 3½ inches apart, with their pocket holes facing upward. Glue and screw the interior slats to the rails, but leave the two end slats loose for now.

6. Attach the seat to the sides

Stand the seat and one side on their back edges as shown. Align the seat rails with the top edges of the lower crosspiece, and then attach the rails to the legs. Repeat the process with the other side. Next, insert one end slat between the seat rails, butt it against the bottom crosspiece, and screw it to the side and seat assemblies. Repeat at the other end with the remaining slat.

Step 7 and 8 — Mock Tuna

7. Add the back rails

Clamp the top back rail flush with the top of the back legs, and then screw it to the sides. Similarly, position the lower back rail midway between the upper back rail and the seat rail, and attach to the sides.

8. Stain and seal the parts

Fill the pocket holes with plugs or wood filler and sand up to 120 grit. Apply stain (if desired) and then two coats of exterior polyurethane or paint. Make sure to thoroughly seal any spots where water can sneak in, including any exposed end grain, pocket holes, and the bottoms of the legs, to protect your piece from the weather.

Materials

Tools