Stackable Cedar Compost Bin


April 17th, 2011

My wife is a big gardener and backyard composting fan. Anna mentioned she wanted a movable compost bin that was roughly three feet cubed. This spring I thought I would try to put something together that would last and make "the pile" look a little more visually appealing. 

Cedar Compost Bin Design

For the general design of the compost bin I thought I would stick with the same cedar design I used previously for some raised strawberry beds I put in a couple years ago. We talked about using treated 
pine instead of cedar this time around but the whole idea of composting in wood that had been treated with what is effectively rat poison was a non starter. Like the raised beds the main building materials were cedar deck boards, 4x4s, and 2x4s. 

Since the idea was to make the bin movable it needed to be light enough to pick up, or at least made of sections that could be moved. I ended up breaking the bin into three stackable pieces: one base section and two identical upper, stackable sections.

To hold the parts together I used some Titlebond extieror wood glue along with exterior deck screws (lots of them). I think if you were on a budget, wood glue plus galvanized nails would work but I really wanted to make sure the assembled sections would hold up when they were being moved around the back yard.

Base Compost Bin Section

The front of the bin needed to be open so it would be easy to shovel stuff in and out. That was a challenge because with the fourth wall missing in the square the side walls could end up being flimsy. To get around that I used a Cedar 2x4 laid flat (see lower, front most board in picture to the left) with some triangle supports to anchor the side walls together. The 2x4 would support the side walls and still be low enough to not impede shoveling compost in and out of the bin.

The corner post where 14" sections of cedar 4x4. The side wall panels were standard cedar decking layered side by side for a total height of 12" (see the raised beds article for details, the same method was used for this compost bin). The triangle supports used in the corners were made from the leftovers. 

Stackable Upper Compost Bin Sections

For the upper sections, the basic design was the same as the base section, sans the front 2x4. Not having the fourth wall made the sidewalls somewhat flimsy on their own. The idea was the base would hold the upper sections sidewalls securely in place once the sections were put together. Along the bottom of the sidewalls I added some interlocking boards that would butt up against the sidewalls of the section below to hold the upper sidewalls in place. 

For the upper sections, I also added some open sections in the sidewalls. The reason for this was to save on the amount of wood I needed and to provide some ventilation which Anna said would be useful to the composting process.

Setup and Use of Cedar Compost Bin

It all went to together well but it did take a while to put together since I glued and screwed all the pieces together. Anna had the idea of placing the base on some straw to hopefully keep the base section a little drier.