What's inside
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A garden bench with curved laminated arms looks more difficult than a straight-sided bench, but the curve is manageable if you build it as a plywood bending form and glue several thin wood strips around it. The result is stronger and more comfortable than a solid piece cut from thick stock, and you can make both arms identical.
Contents
Choose the design and materials
This plan makes a two-person bench about 48 inches wide, 18 inches deep, and 34 inches high. The seat is 18 inches above the ground. Adjust the width if needed, but keep the seat slats supported at least every 24 inches to prevent uncomfortable flexing.
| Material | Best use | Trade-off |
|---|---|---|
| Cedar | Lightweight outdoor bench with natural rot resistance | Soft and easy to dent; usually costs more than treated lumber |
| Pressure-treated pine | Lowest-cost frame and legs | Wet, heavy, prone to movement; must dry before finishing |
| White oak | Hard, attractive arms and trim | Expensive and heavier; requires careful sealing |
| Douglas fir | Strong painted bench parts | Needs thorough paint or exterior stain maintenance |
For a practical build, use cedar for the seat and back slats, and cedar, treated pine, or fir for the frame. Avoid ordinary indoor plywood for the bending form if it will be left outside. The form is temporary, but it still needs to stay flat while the glue cures.
You will need exterior-rated wood glue, 2 1/2-inch and 1 1/4-inch exterior screws, a drill, countersink bit, clamps, a circular saw or miter saw, and a jigsaw. A set of parallel bar clamps makes the laminated arms easier to assemble, though several ordinary pipe or bar clamps work too.
Cut the bench parts
Cut the following parts from straight, dry stock:
- Four legs, 2 by 4 by 17 inches
- Two front and rear seat rails, 2 by 4 by 45 inches
- Two side seat rails, 2 by 4 by 15 inches
- Six seat slats, 1 by 4 by 48 inches
- Three back slats, 1 by 4 by 48 inches
- Four arm laminations for each arm, 1/4 by 3 by 25 inches
- Two arm supports, 2 by 4 by about 24 inches
The arm laminations should be ripped from clear, straight-grained stock. Four strips at 1/4 inch thick produce a one-inch-thick arm. Do not use short offcuts joined end to end; those joints are weak in a bent part and will show as the arm ages.
Build the seat base
Assemble the two side rails between the front and rear rails, forming a rectangle 45 inches long by 18 inches deep. Put the front and rear legs inside the corners so the outside face of each leg is flush with the frame. Predrill every screw hole, especially in cedar, which splits easily near the ends.
Fasten each leg with two 2 1/2-inch exterior screws through the rails. Check that the base sits flat before tightening all the screws. Add a pair of 2-by-4 cross supports under the seat, spaced roughly 15 inches from each end. These supports carry the slats and keep the frame from racking.
Install the seat slats with a 3/8-inch gap between boards. Use a scrap of plywood as a spacer. Let the slats overhang the front and back rails by about 1 1/2 inches, then drive two screws into each support. Sand or ease every exposed edge with 120-grit paper; sharp outdoor furniture edges are uncomfortable and shed finish quickly.
Make the curved laminated arms
Draw the arm curve full-size on a piece of 3/4-inch plywood. A simple curve starts 2 inches above the front of the arm support, rises about 4 inches through the middle, and returns to the rear support. Use a thin strip of wood as a flexible batten rather than trying to draw the curve freehand.
Cut two identical plywood form pieces and screw them to a flat base with spacers between them. The laminations will sit in the curved channel. Cover the form with packing tape or polyethylene so glue cannot bond the arm to it. Add several plywood clamping blocks along the curve.
Spread a continuous, thin coat of waterproof exterior wood glue on both mating faces of each strip. Stack four strips, place them in the form, and tighten clamps from the center outward. Work quickly; many exterior glues give you only 10 to 15 minutes of useful assembly time.
Use enough pressure to close the gaps, but do not crush the soft wood. If glue squeezes out evenly along the curve, pressure is adequate. Leave the arm clamped for the full cure time on the label, normally at least 24 hours. Rushing this step is a common failure mode: the arm can spring open or develop hairline glue joints when removed.
Make the second arm in the same form. After curing, trim the ends square, round over the top edges, and sand to 120 or 150 grit. A flush-trim router bit can clean the laminated edges, but a block plane and sanding block are cheaper and work well.
Install the back and arms
Attach the arm supports to the outside of the legs with two screws at each joint. Set them so the finished arms will be about 24 inches above the seat. Test the height with a scrap board before drilling; a small adjustment is easier now than after the curved arms are attached.
Fasten each laminated arm to its support with glue and four 1 1/4-inch screws driven from underneath. Predrill and countersink the holes. Plugging the holes is optional, but exposed screw heads are more likely to collect water and rust.
Mount the three back slats between the rear legs. Leave 3/4 inch between slats, and tilt the back assembly rearward about 10 degrees if you want a more relaxed sitting position. Use a temporary spacer block to keep the gaps consistent. Round the top back slat’s edges thoroughly.
Finish the bench for outdoor use
Let fresh cedar dry for several days before finishing. Pressure-treated lumber may need several weeks, depending on weather; finish only when a water drop soaks in rather than beading on the surface. A penetrating exterior oil is simple to renew and does not peel, but it needs maintenance every year or two. Exterior paint protects longer when applied over a suitable primer, but peeling paint requires scraping and sanding.
Apply finish to end grain, especially the bottoms of the legs and the ends of the laminated arms. Keep the bench off wet soil with rubber feet, paving stones, or a gravel pad. In winter, cover it loosely so air can circulate. Tight plastic wrapping traps condensation and encourages rot. Inspect the arm glue lines and leg bottoms each spring; repair cracks before water can enter.
A cheaper straight-arm bench is fine if speed and cost matter. The laminated version earns its extra work through better comfort and a distinctive shape, but only if the glue joints stay dry and the curve is clamped evenly.