Three Compartment Compost Bin

I have been wanting to build a three compartment compost bin for some time now. However, I just couldn't come up with a design I was happy with. I spent considerable time searching the web for ideas, but most weren't what I was looking for.Then I found a compost bin on the web created by Michael Wood and Robyn Oxley, which was basically what I was looking for, but needed some modifications in order to meet my needs. They only had two pictures, and no plans, but it was pretty straight forward to figure out. They had a top that slanted forward and I didn't want rain water to run in front of the bin, but off the back as I was placing the bin near a bank on my property. I also wanted to secure the front in a manner that would keep the front board slots parallel so the boards that slide in and out wouldn't bind. I also wanted a screen sifter for the third bin so I could sift the final compost product. With a little time and effort, and the help of my stepson Jonas, the project was completed in a weekend.

The entire project was built with pressure treated wood. I used wire mesh for the sides and inside compartments. As opposed to chicken wire, which is often used, I selected wire mesh called "Weld Mesh" because it has a square grid and is welded at each joint. This is often used for rabbit coops and I like the finished appearance. Here are some further photos of the finished project with some additional information and specifications.

This is a view of the completed Three Compartment Compost Bin with the top closed.

The completed unit measures 95" long x 38-3/4" deep x 44-1/2" high at the front (40-1/2" at the back). The four front dividers are held parallel by using "T" Posts pounded into the ground and then secured to the front with screws. The Screen Sifter can be observed in the third section and can set in place with the roof closed.

Each compartment side is made from 2x4's and the finished square is 36" x 36". In order to pitch the top to the rear, the front boards, used for the front of the front board slots, were made four (4) inches higher than the 2x4 frame.

A view of the left side with the top down.

A view of the right side with the top down.

A view of the front with the top open. The screen sifter can be seen at right.

A view from the left front with the top open. 

A view of the front with the top open and the boards removed from the center compartment.

A view looking straight down at the center compartment showing the slots for the front boards.

The front boards are 5-1/2" x 3/4" x 27" wide. These boards are 4" higher than the 36" 2x4 square, and hang over each side of the 2x4 one (1) inch, providing the front of the board slot. Each compartment holds seven (7) boards. The boards for the inside of the slot are 1-1/4" x 5/8" and 36" long.

A side view of the slots in the center compartment for the front boards.

A front view of the screen sifter in the top of the third compartment.

After adding compost from the second compartment, you place it in the sifter, and hold the front handles, you slide the sifter from front to rear, sifting the final compost product.

A view of the screen sifter from the right side.

A view of the screen sifter from the center compartment (left side).

A closer view of a "T" Post, which was pounded into the ground in front of each front
upright. It was then screwed to the front. These help to ensure that the compartments
remain square so the boards slide up and down smoothly.

A view of the Hook and Eye hardware used on each end to hold the top down when windy.

A close view of the Pivoting Roof Prop which holds up the top when open. It pivots back when the top is closed.

The total length of the Three Compartment Compost Bin is 95" (1" shorter than 8') This provides 27" between each compartment. Well there you have it. I like the finished product and now I have to get busy filling it so I can get some compost for next spring planting.

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Copyright © 2014 by John D. McCann