How to Build a Bench
Updated: Aug. 18, 2023
Build it in an afternoon!
The sloped seat and backrest make this easy-to-build bench comfortable to sit in and perfect for a backyard deck, patio or firepit. Detailed, clear photos show construction details.
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A full day
Photo 1: Cut the parts
Cut out the bench parts following the measurements in Figure A. Use a square to guide the circular saw for accurate, square cuts. Cut 45-degree angles on the ends of the seat and back supports 1 in. down from the ends as shown (also see Photos 4 and 5).
The beauty of this cedar bench isn’t just that it’s easy to assemble and inexpensive—it’s that it’s so doggone comfortable. You can comfortably sit on your custom-fit bench for hours, even without cushions. In this story, we’ll show you how to build the bench and how to adjust it for maximum comfort.
Sloping the back and the seat is the secret to pain-free perching on unpadded flat boards. But not all bodies are the same, and it’s a rare piece of furniture that everyone agrees is seatworthy. This bench has a bolted pivot point where the back and seat meet that lets you alter the backrest and seat slopes to fit your build during one of the final assembly steps (Photo 10). The materials are inexpensive, and cutting and assembly will only take about three hours. Follow the step-by-step photo series for details on the simple construction.
Figure A: Bench Parts
All the pieces for this bench design are cut from eight 8-ft. long boards. (A larger, PDF version of Figure A is available in Additional Information, below.)
Build it from eight 8-ft. long boards
Photo 2: Fasten leg brace to legs
Fasten the leg brace to the legs 3 in. above the bottom ends. Angle the 3-in. screws slightly to prevent the screw tips from protruding through the other side. Hold the brace 1/2 in. back from the front edge of the front leg. Use a square to make sure the brace and legs are at exact right angles.
Photo 3: Complete the front leg
Align the second part of the front leg with the first one using a square and screw it to the leg brace as shown.
Photo 4: Add the seat support
Slip the seat support between the two front legs, positioning it as shown. Drive a single 3-in. screw through the front leg into the seat support.
Photo 5: Add the backrest
Position the backrest support on the leg assembly as shown, making sure it’s at a right angle with the seat support, and mark the position on the seat support. Then drive a 3-in. screw through the middle of the backrest support into the leg brace.
Photo 6: Finish the leg assemblies
Clamp the backrest support, seat support and rear leg as shown using the line as a guide. Drill a 3/8-in. hole through the center of the assembly. Drive a 3/8-in. x 5-in. bolt fitted with a washer through the hole and slightly tighten the nut against a washer on the other side.
Photo 7: Add the stretcher
Build the other leg assembly for the bench to mirror the first as shown. (The back support and rear leg switch sides.) Prop the stretcher 3 in. above the workbench, center it between the front and rear bench legs and screw the leg braces into the ends with two 3-in. deck screws.
Photo 8: Attach the seats
How to make a bench seat: Center the first 2×4 seat board over the leg assemblies and flush with the front ends of the seat supports. Screw it to the seat supports with two 3-in. deck screws spaced about 1 in. away from the edges. Line up the 2×10 with the first 2×4, space it about 5/16 in. away (the thickness of a carpenter’s pencil) and screw it to the seat supports with two 3-in. deck screws. Repeat with the rear 2×4.
Photo 9: Build the backrest
Rest the bottom backrest 2×4 on carpenter’s pencils, holding the end flush with the seat boards, and screw it to the seat back braces. Then space and screw on the center 2×10 and the top 2×4 backrest boards.
A circular saw and a screw gun are the only power tools you really need for construction, although a power miter saw will speed things up and give you cleaner cuts. Begin by cutting the boards to length. Figure A shows you how to cut up the eight boards efficiently, leaving little waste. When you’re picking out the wood at the lumberyard, choose boards that above all are flat, not twisted. That’s especially important for the seat and back parts. Don’t worry so much about the leg assembly 2x4s because you cut them into such short pieces that warps and twists aren’t much of a concern.
After cutting the pieces to length, screw together the leg assemblies (Photos 2 – 6). It’s important to use a square to keep the leg braces square to the legs (Photo 2). That way both leg assemblies will be identical and the bench won’t wobble if it’s put on a hard, flat surface. We spaced the leg brace 1/2 in. back from the front of the legs to create a more attractive shadow line. Then it’s just a matter of connecting the leg assemblies with the stretcher (Photo 7), screwing down the seat and backrest boards, and adjusting the slopes to fit your body.
Adjust the back and round over the edges
Photo 10: How to make a bench seat that’s perfect for you: Test the fit
Sit on the bench and decide if you’d like to tilt the seat or the backrest or both to make the bench more comfortable. To make seat or back adjustments, loosen the bolts and clamp the bottoms of the seat back supports and the fronts of the seat supports. Then back out the four screws at those points. Loosen the clamps, make adjustments, then retighten and retest for comfort. When you’re satisfied with the fit, drive in the four original screws plus another at each point. Retighten the pivot bolts.
Photo 11: Cut the seat trim boards to fit
Tack the seat trim boards to the seat with the ends flush with the front and top. Scribe and cut the trim boards to fit. Nail the boards to the seat and backrest boards with 6d galvanized casing nails, keeping the nails 1 in. back from the seat edges.
Photo 12: Round the trim boards
Ease the edges of the trim boards with a router and a 1/2-in. round-over bit. Hold the router sideways to get at the seat/back corner.
The easiest way to adjust the slope is to hold the four locking points in place with clamps and then back out the temporary screws (Photo 10). To customize the slopes, you just loosen the clamps, make the adjustments, retighten and test the fit. When you’re satisfied, run a couple of permanent screws into each joint. If you don’t have clamps, don’t worry—you’ll just have to back out the screws, adjust the slopes, reset the screws and test the bench. Clamps just speed up the process.
We show an option of rounding over the sharp edge of the 1×3 trim,which is best done with a router and a 1/2-in. round-over bit (Photo 12). Rounding over the edges can protect shins and the backs of thighs and leave teetering toddlers with goose eggs on their melons instead of gashes. So the step is highly recommended. If you don’t have a router, round over the edge either by hand-sanding or with an orbital or belt sander. In any event, keep the casing nails 1 in. away from the edge to prevent hitting the nailheads with the router bit or sandpaper (Photo 12).
Building a longer bench
We demonstrate how to build a 4-ft. long bench, plenty of space for two. But you can use the same design and techniques for building 6- or 8-ft. long benches too.You’ll just have to buy longer boards for the seat, back, stretcher and the trim boards.While you’re at it, you can use the same design for matching end or coffee tables. Just match the double front leg design for the rear legs, and build flat-topped leg assemblies with an overall depth of 16-3/4 in.
Seal the legs to make it last
If you want to stain your bench, use a latex exterior stain on the parts after cutting them to length. After assembly, you won’t be able to get good penetration at the cracks and crevices. Avoid clear exterior sealers, which will irritate bare skin. But the bench will last outside for more than 20 years without any stain or special care even if you decide to let it weather to a natural gray. However, the legs won’t last that long because the end grain at the bottom will wick up moisture from the ground, making the legs rot long before the bench does. To make sure the legs last as long as the bench, seal the ends with epoxy, urethane or exterior woodworker’s glue when you’re through with the assembly.
Though this wooden seat would be great on it’s own anywhere around your yard, you could also make a couple and turn them into built in deck benches with backs by attaching them to your deck.
Required Tools for this Project
Have the necessary tools for this DIY project lined up before you start—you’ll save time and frustration.
See complete material list in Additional Information
Originally Published: June 12, 2019