Three Bay Compost Bin Plan

This three bay compost bin plan will create a large composting system for serious composters.  The three sections allow you to have several batches of compost going simultaneously.



  1. Cut two 32″ and two 36″ pieces from each 12 foot 2×4.  Nail the four pieces into a 35″ x 36″section.  Check to make sure each divider section is square. Repeat for other three. Cut four 37″ long sections of hardware cloth, bend back edges 1″.  Stretch hardware cloth across each frame, check for squareness of the frame and staple screen tightly into place every 4″ around edge.
  2. Set up dividers parallel to each other 3 feet apart.  Measure centers for the two inside dividers and mark.  Cut four 9 foot pieces out of the two 18 foot 2×4 boards. Place two 9 foot base boards on to the dividers and measure the positions for the two inside dividers. Mark a center line for each divider on the 9 foot 2×4. With each divider, line up the center lines and make the baseboard flush against the outer edge of the divider.
  3. Drill a 1⁄2″ hole through each junction centered 1″ in from the inside edge.   Fasten baseboards with bolts, but do not tighten.  Turn the unit right side up and repeat the process for the top 9 foot board.  Using the square or measuring between opposing corners, make sure the bin is square, then tighten all bolts securely. Fasten a 9 foot long piece of hardware cloth securely to the backside of the bin with staples every 4″ around the frame.
  4. Cut four 36″ long 2x6s for front runners. Cut lengthwise two of these boards to 4 3 ⁄4″ wide and nail them to the front of the outside dividers and baseboard, make them flush on top and outer edges.  Save remainder of boards for use as back runners.   Center the remaining full width boards on the front of the inside dividers flush with the top edge, and nail. To create back runners, cut the remaining 2×6 into a 34″ long piece and then cut into 4 equal pieces, 11⁄4″ x 2″. Nail back runner parallel to front‐runners on side of divider leaving a 1″ gap for slats. Cut all the 1×6″ cedar boards into slats 31 1⁄4″ long.
  5. Use a 9 foot 2×4 for the back of the lid. Cut four 32 1⁄2″ 2x2s and one 9 foot 2×2. Lay out into position on ground and make sure they are square. Screw in corner braces and T‐braces on bottom side of the frame. Center lid frame, brace side down on bin structure and attach with hinges. Cut molding board to fit the front and back 9 foot sections of the lid frame. Pre‐drill molding board with 1⁄8″ drill bit and nail with casement nails. Cut fiberglass to fit flush with front and back edges. Overlay pieces at least one channel wide. Pre-drill fiberglass and molding board for each nail hole. Nail on top of every third hump with gasket nails.