How to Build a Compost Bin in Your Own Backyard
Perhaps you’ve been thinking about it for a while now, and you’ve decided that your family needs a compost bin in your backyard. You could go out and buy one of those really nice, plastic-barrel ones, the kind that sits on a fancy rack and rotates with a spin of the handle. But you don’t have to shell out a couple hundred dollars or experience the frustration of trying to assemble it when you get it home. Build your own. It’s less expensive, relatively simple to construct, and — as important, in my mind — easy to disassemble and repurpose if you ever want to. And it takes you one step further on your green living journey.
I’m always looking for reasons to avoid buying anything new, especially new plastic things. I like to use old stuff when I can; it’s eco-friendly and helps create a sustainable lifestyle. Better yet, I prefer to make my own. But I have to be careful to not get carried away. I tend to over-design, and then over-build, so my projects end up costing twice as much and taking twice as long as yours might. Most people build their compost piles with four stakes and some chicken wire wrapped around the outside. That’s an option, of course, but it’s not raccoon-proof, and that was my first requirement.
Well, anyway, I had this compost design in my head for about a month, and I finally got around to building it. First, I listed my essential design requirements:
- It has to keep the raccoons out. The patriarch of the local raccoon family and I have had an ongoing battle over my trashcans for 5 years. Right now, I have about 10 bungee cords on every trashcan, but he still figures out how to get inside them and spread the contents all over the place. So, from now on, no more food in the trash cans. All food waste goes into the compost bin, and that bin has got to be tough. It has to have a cover that this miniature Houdini cannot lift, pry off, or dismantle (I fully expect to see him down at the local hardware store buying a jack hammer) while, at the same time, allowing a normal-sized adult human to open the lid and dump in our food waste. <strong></strong>
- It has to last. I don’t want to have to rebuild it every spring because it collapsed when a leaf fell on it. I would like it to outlive me. This is just my theory of construction. A few extra materials and a bit more effort now mean I can forget about it later
- It has to be mostly enclosed. For one thing, I don’t want to have to look at it. To me, there’s something less-than-attractive about maggots, flies, and worms romping through rotting food. I know they’re all necessary for a compost pile, but they’re not too pretty in the middle of a flower garden. And for another, if it’s too open, the compost will dry out, slowing the decaying process.
- It also has to have openings. Bugs, snakes, and spiders have to be able to get in or out. Worms need access from the bottom. And I want rain to fall into it from the top, because moisture helps the whole process move along.
- It has to be easily dismantled. Once a season or so, I’ll need access so I can stir the contents. And once a year, I’ll remove the good soil from the bottom.
Once I decided on my essential requirements, I went looking for the supplies I needed. First, I looked in my yard and garage to scavenge any useful materials. The rest, I purchased at my local lumberyard for less than $100. (For items I already had, I’m giving an estimated cost.)
- 56 – 8 inch x 8 inch x 8 inch concrete blocks @ $0.95 each (on sale). (I had to bring them home in two loads to save the shocks in my Prius.): $56.00
- 2 – 8-foot 2” x 8”s of green-treated wood @ $5.50 each: $11.00
- 1 roll of chicken wire fencing, 4 feet x 10 feet: $8.00
- 2 pull handles (scrounged from my garage): $10.00
- 2 door hinges (also free from scrounging): $10.00
- Assorted nails, staples, screws (again, stuff I had around): $3.00
Of course, I also had the shovel and hoe to level the soil in our flower garden. These would be additional costs, if you don’t have them already. I also take it for granted that I have a drill, a circular saw, sawhorses, levels, a square, a staple gun, tin snips, and a tape measure to accomplish the rest of this project. If you don’t have these tools, you can rent them at your local rental store — or borrow them from a willing neighbor (but be sure to return them promptly and in great condition if you want your neighbor to remain willing).
A word of caution: If you don’t have basic carpentry skills, you may be better off buying that big plastic barrel that comes in a kit. Handling a circular saw or a drill can be dangerous. You don’t want to end up composting a body part.
- Choose the location. You’ll need to do this before you run off to the hardware store, of course. I chose to locate the box in the center of a flower bed, along a length of wood fence, where I could plant some taller flowers next season to hide it. You can build your compost any size. My surface space was about 48 inches wide by 40 inches front to back. I calculated the number of blocks this would take before making my purchase. If you want a larger or taller box, buy more blocks.
- Prepare the ground. It took me about 20 minutes to level the ground. You must start with a flat surface. Use your level to check it. Tamp it lightly. We’re not using any mortar between the blocks, so, if your blocks are set on any slope, they will not stand. Start building. I set the bottom layer of blocks in place, in a rectangle, side by side, with the flat surfaces of the blocks to the inside. I continued to lay the next two layers of blocks on top of those. All that took about another 20 minutes. Note that I don’t recommend using any mortar, so the blocks can be freely removed from any or all sides. Be aware that the blocks will eventually settle, tip, and separate, especially if you only put a light piece of plywood on the top as a cover (which is an option). If you choose the lid design that I used, it will be heavy enough to help hold the blocks in place for a considerably long time.
- Build the lid. I decided to go for the deluxe lid, so I cut the 2 x 8 for the back anchor board and the front face board, both at 46 inches in length. Then I mitered the corners for the front board. I wanted a cleaner look than just toe-nailing a right-angle joint. I then cut the two 31-inch side boards. I matched up their mitered corners on the front to the matching 2 x 8, and on the back to a 2 x 4 that I ripped from the remaining 2 x 8 stock. To assemble the frame, I toe-nailed all the pieces together with some 8 penny galvanized nails and set all the mitered corners with some four inch coated deck screws, just to be safe. Cutting all the pieces took less than 20 minutes, and assembly took another 20.
- Attach the hardware. I screwed the door hinges on the back and the pull handles on the front of the lid frame. I laid the whole contraption in place on top of the blocks, placing the last two blocks on top of the back anchor board, and flipped the lid open.
I cut the chicken wire to fit using a tin snips, then stapled it into place on the underside of the lid. I tapped the staples down with a hammer to make sure the raccoons couldn’t get the tips of their little crowbars under it. I made sure the sharp tips of the chicken wire were also hammered flat to not scratch any skin when the lid was opened and closed. Attaching the hardware and chicken wire took another 20 minutes.
So, it took me a little over an hour to get two loads of blocks home from the lumberyard, and another two hours of building. For about $100 worth of materials, I now had my first compost. It’s a little sturdier than most I have seen, but remember, I have Guido, the 80-pound raccoon to deal with.
Besides being extra strong (and foiling even the cleverest local raccoon bandit), this compost bin is extremely flexible. If the pile of decaying matter isn’t shrinking fast enough, I can turn one or more of the lower-level concrete blocks a quarter turn and allow more air to enter the box. This should cook the contents a little faster if things begin to fill up too fast. And, if we have a lot more yard waste or food waste than I anticipate, I can easily add more layers of blocks to the top of the box. Since the lid isn’t screwed into the blocks, it’s a simple mater to remove it and then replace it on top of the new layers.
The process of composting needs air, water, carbon, and nitrogen. The carbon is the dead, brown, dry yard waste, and the nitrogen is the green yard waste and food scraps. You want to have a balance of the two. If you find you are putting in too much food waste, and your compost pile is beginning to smell, just add some shredded paper, cardboard, straw, or fall leaves. These will contribute carbon and air space to the mixture. And don’t forget to stir the mixture every month or so with a pitch fork (or a shovel if you don’t have a fork).
Anyway, the important thing here is not what your compost box or bin looks like, it is that you get some kind of container and start using it. Composting your food waste and yard waste should become as natural as recycling your plastics, tin cans, paper, and glass.
Composting helps reduce the tonnage that goes into landfills, provides a home for many creatures, builds your lawn and garden with amazing nutrients, and gives you the sense that you are giving something back to your good earth.
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