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The project:
A hot compost bay is a simple and effective way to manage garden and kitchen waste while producing nutrient-rich compost for your garden. A well-designed bay provides good airflow, retains heat and makes it easy to add, turn and remove compost.
This design uses 70 x 35mm H3 framing timber for the uprights, Pine decking boards for the horizontal slats, and chicken wire to contain the compost while maintaining airflow. A removable front allows you to gradually build the pile and provides easy access for turning and harvesting finished compost.
Many thanks to community member Tim Jeffries for providing inspiration for this project with his popular hot composting bays.
- Video tutorial:
- Materials:
- Tools:
- Step 1:
Cut the timber for the frame.
Start by cutting all your timber to length, ensuring your cuts are square. Keeping all cuts square and consistent by using a speed square or cutting with a mitre saw will make the assembly process much smoother and help ensure the structure sits level and stable.
Remember to wear safety glasses, hearing protection and a dust mask when cutting timber. Ensure the timber is fully supported on a stable work surface or saw horses and secure it to prevent movement while cutting. Always keep your hands clear of the blade and follow the manufacturer's safety instructions for your power tools.
Cut four pieces of 70 x 35mm H3 framing timber to 1200mm.
Cut sixteen pieces of 90x22 H3 Pine decking to 1200mm.
Cut thirteen pieces of 90x22 H3 Pine decking to 1030mm.
Cut six pieces of 42x18 to 1200mm.
- Step 2:
Coat the timber with oil.
Coat all timber with raw linseed oil to help protect it from moisture, rot and weather exposure. Linseed oil is a good choice from a sustainability perspective, as it is plant-based and low-toxicity once cured, making it suitable for use around compost. Pay extra attention to the end grain, as this is where timber absorbs the most moisture. Allow the oil to soak in and fully dry before moving on to assembly.
- Step 3:
Assemble the compost bin frame.
Construct the main structure by fixing the 70 x 35mm uprights and horizontal decking boards together to create the two side panels.
Mark the locations of the decking boards on the 70x35 so that they are evenly spaced. Clamp the top board in place while screwing in the bottom board, checking for square as you go. Ensure you drive two screws through each decking board to prevent them from pivoting.
Connect the two side panels using the four remaining 1200mm decking boards to form the back of the compost bay and complete the main frame. The framing timber should be on the outside of the compost bay, and the ends of these decking boards should sit flush with the outside of the framing. This will mean the horizontal decking boards are all on the inside of the structure.
Again, use your clamps to hold the decking boards in place while predrilling and screwing and check for square as you go. An easy way to check for square is measuring diagonally across the compost bin and ensuring those distances are the same. Make small adjustments to the frame to correct differences.
- Step 4:
Position and stake the compost bin.
Place the compost bay in a suitable location on well-drained ground. Check that it is sitting level. Remove or add soil beneath the frame as required.
Once level, stake the back two corners with 60cm stakes. Secure each stake to the 70x35 framing with two galvanised hex-head screws per stake.
With the rear of the compost bay fixed in place, use the 165cm stakes to secure the front corners. The longer stakes help maintain a consistent opening width from top to bottom, ensuring the decking boards that form the removable front can slide freely within the guide slots.
Drive a stake into one side of the opening and then secure it to the frame with three galvanised hex-head screws.
Next, clamp a decking board to the inside face of the frame on each side of the opening. These boards will act as temporary guides. Slide one of the 1030mm decking boards up and down between them to confirm the opening is the correct width and that the decking board moves freely.
Once satisfied, drive the final stake into the opposite side of the opening, again ensuring it remains plumb. Check that the decking board can still slide up and down easily, then secure the stake to the frame with three galvanised hex-head screws.
- Step 5:
Attach the chicken wire.
Remember to wear gloves when handling the chicken wire, as the cut edges can be sharp.
Position one end of the chicken wire on the inside face of the compost bay and hold it in place with clamps. Attach one of the remaining 1200mm decking boards flush with the front of the frame, sandwiching the chicken wire between the board and the frame to secure the starting edge.
Unroll the chicken wire around the inside of the compost bay, keeping it taut as you work. Use clamps as required to hold the wire in position.
At each rear corner, use one of the 42 x 18mm timber pieces to sandwich and secure the wire. Continue around the structure, fixing the remaining boards in place and trapping the wire between the boards and frame.
Once the perimeter boards have been installed, use galvanised staple nails to secure the chicken wire to the horizontal rails for additional support and to prevent sagging.
Trim any excess wire with aviation snips.
- Step 6:
Attach the front trim piece.
Attach the final two 1200mm decking boards to the front of the compost bay. Position each board so its inside edge is flush with the face of the vertical guide board inside the opening, then secure it with galvanised screws.
These trim boards will conceal the exposed edges of the chicken wire and give the front of the compost bay a neat, finished appearance.
- Step 7:
Attach the guides for the removable front.
Attach one of the 42 x 18mm boards to the front face of the vertical guide board so it is flush with the front of the opening. This board forms the front side of the guide channel.
Next, attach a second 42 x 18mm board to the rear face of the vertical guide board. Use an offcut of decking as a spacer while positioning the board to ensure the channel is the correct width. Before fixing it permanently, check that the offcut slides freely within the channel. If it binds at any point, adjust the board position until the fit is smooth.
Repeat this process on the opposite side of the opening.
Once both guide channels have been installed, insert several of the 1030mm decking boards into the opening to confirm they slide freely and the removable front operates as intended.
With your compost bay complete, you will now have a durable and easy-to-use system for producing quality compost at home.
