We love a good garden bench. A better garden bench is one that doubles as a compost bin. Inspired by benches at the Brooklyn Botanic Garden, in Brooklyn, New York, this one is open-bottomed so that the compost has ground contact. It’s made of rot-resistant cedar boards spaced wide to promote good air circulation. The seat opens for easy turning of the compost, and the back and arms make it a perfect perch for a break from gardening.
Follow along as This Old House contributor Christopher Beidel, owner of Pernt, a handmade-furniture company in Brooklyn, shows you how to make this piece—as practical as it is pretty.
Overview of How to Build a Compost Bench
- Day 1: Build the base and seat (Steps 2-10).
- Day 2: Make and install the backrest and arms (Steps 11-18).
Steps for Making a DIY Compost Bench
Step 1: Make the right-angle cuts
On your miter saw, make the straight cuts for all the parts, according to the cut list.
Step 2: Make the angled cuts
- The four blanks for the angled brackets are sized so that when you cut them diagonally you get two pieces from each blank.
- Clamp one corner of a blank to your work surface, and draw a diagonal line corner to corner.
- Set the circular-saw blade to a depth of 1⅝ inches. Make the crosscut, as shown, to create two angled pieces. Repeat the process on the other three blanks.
Step 3: Make the corner posts for the base panels
- Clamp two 2×4 pieces for a front corner post together edge-to-face in an L-shape, as shown.
- Use a combination countersink bit in your drill/driver to make three pilot holes through the face and into the edge.
- Secure the pieces with 2½-inch deck screws. Make the other front corner post.
- For the rear corner posts, butt the edge of a short 2×4 into the face of the long piece for the backrest.
Step 4: Assemble the front panel
- Lay the front corner posts on your work surface with the edge-to-face seam facing out, and place three base slats between them.
- Use a hunk of 1x scrap to set the top slat ¾ inch down from the post tops, leaving room for the cap piece in Step 10. Then use ⅜-inch spacers to set the distance between the slats.
- Countersink two pilot holes through the slats and into the posts, at least ½ inch from the ends of the slats. Secure the slats with 1¼-inch deck screws.
Step 5: Attach the batten
- Set a batten across the center of the slats. Countersink three pilot holes in a triangular pattern, through the batten into each slat.
- Secure the batten to the slat with 1¼-inch deck screws. Build the back panel the same way, including the ¾-inch space for the cap.
Step 6: Attach the side slats to assemble the base
- Start with the back panel on the table. Clamp a side slat against a post, aligning it with the abutting slat, as shown. (Remember to maintain the ¾-inch setback from the post top.)
- Countersink three pilot holes through the short slat into the post, and secure it with three 1¼-inch deck screws in a triangular pattern.
- Repeat the process on the other five side slats, using spacers between boards.
Step 7: Add the front panel to the base
- Set the front panel on top of the side slats.
- Again, countersink pilot holes through the slats into the posts, and secure the pieces with 1¼-inch deck screws.
Step 8: Assemble the seat slats
- Lay the seat slats with ⅜-inch spacers between them, and clamp them together. Arrange the three battens, one in the center of the seat, the other two 12 inches to either side, and all three set back ¾ inch from the seat’s front edge.
- Countersink pilot holes through the battens and into the slats and drive 1¼-inch deck screws into place.
Tip: Cedar is rot-resistant, but you can keep your bench looking its best longer by finishing it with a transparent weather-proofing sealer.
Step 9: Attach the cross brace
- Clamp the 2×4 cross brace between the tops of the center battens. Countersink pilot holes through the face of the top slat into the end grain of the cross brace at both ends. Then secure the piece with 2½-inch deck screws.
- Set the base upright, and position the three cap pieces along the back edge and the two sides.
- Countersink these and secure them with 1¼-inch deck screws.
Step 10: Attach the backrest brackets
- Clamp the 1×6 footer for the backrest on edge to your work surface. Set three backrest brackets in place along the footer, as shown.
- Countersink two pilot holes through the underside face of the footer and into the end grain of each of the brackets. Then secure them with two 2½-inch deck screws apiece.
Step 11: Attach the cross supports
- Place the two horizontal cross supports on the cut edges of the backrest brackets, top and bottom.
- Countersink pilot holes through the supports into the brackets, as shown. Secure with 1¼-inch deck screws.
Step 12: Install the slats
- Set the slats for the backrest on the horizontal supports. Use spacers to set the pieces ½ inch apart and ¼ inch from the ends.
- Countersink pilot holes from the back of the assembly into the slats, and secure them with 1¼-inch deck screws.
Step 13: Attach the backrest
- Align the backrest assembly on top of the rear cap and post tops, as shown. Countersink pilot holes through the back of the 2×4 posts into the back of the angled brackets.
- Secure the assembly with 2½-inch deck screws. Then use 1¼-inch deck screws to secure the footer to the cap from behind.
Step 14: Make the armrests
- Clamp an armrest board on edge to your work surface.
- Countersink pilot holes through the armrest and into the brackets, and secure the pieces with two screws per bracket: one 2½ inches, the other 1¼ inches. Repeat the process for the other armrest.
Step 15: Attach the armrests
- Clamp the top of the armrest assembly about 6 inches above the seat. Use the combo countersink bit to drill two pilot holes, bottoming it out at the top location.
- Secure the bracket to the corner post with a 2½-inch screw at the top location and a 1¼-inch deck screw at the bottom location.
- Repeat the process on the other bracket. Install the other armrest.
Step 16: Secure the hinge
- Set the bench seat faceup on a 1x spacer that runs its full length. Set the open hinge against the seat’s back edge, with the barrel facing forward, and mark the holes with a pencil.
- Remove the hinge and use a 1/16-inch bit to make pilot holes along the edge. Then use a screwdriver to secure the hinge to the seat with the included screws.
- Now set the seat in a raised position with the hinge leaf against the edge of the backrest footer. Make pilot holes and attach the hinge leaf.
Step 17: Install the seat lip
- Open the seat and center the 1×1 lip into the gap in front of the seat battens. Countersink eight pilot holes through the edge of the cleat into the seat slat.
- Secure the cleat with 1¼-inch deck screws.
- Set the bench in place and shovel in some yard waste to get the composting started.
Step 18: Keep it fresh
Turning compost regularly and keeping it free of meat and dairy scraps are critical to preventing odors.