How to Build a 3-Bin Composter for Less Than $5

This DIY 3-bin composter lets you mix your food scraps in one compartment, turn the organic matter in another, and store finished, fresh compost in the final one. And you can build your own compost bin out of free pallets for next to nothing with just a few easy steps!

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I’ve been wanting my own compost bin forever.

When we first moved to our property, there was already an old compost pile that had been left sitting for years by the previous owners. I’m sure there was probably some great compost underneath the grass clippings that covered the top. But we had a lot on our plates when we first moved, so we didn’t really “do” anything with the compost heap aside from add to it. And add to it we did…

In fact, all we ever did was add to it. I was just happy to have a place to toss our kitchen waste, yard waste, and dry leaves on our property.

Before, when we lived in the city, we had no choice but to throw all of our food waste and vegetable scraps away until it became mandatory for all buildings to get a green bin. But even then, we couldn’t really benefit from our own organic waste.

Naturally, when we moved to our current home, I was excited at the prospect of starting the garden I had always dreamed of and of using a nutrient-rich soil amendment made by us to feed our vegetable garden. But I didn’t know much about the composting process other than what you could toss in a compost pile. So we just continued to toss.

The following summer, we were too busy putting in our raised beds, getting fresh soil delivered, and having a baby to worry about dealing with the compost pile. We didn’t have a pitchfork to turn it and it was turning into a compost mountain. We knew there was probably lots of fertile, wormy, fresh soil buried in there somewhere, but we just had too much going on to get to it, and it was low on our to-do list. 

By the end of that summer, weeds began to grow wildly out of the pile and the bramble had found its way over as well. Our potentially rich soil was now being tainted by awful weeds that we definitely didn’t want in our garden!

By the time we were ready to start prepping our soil again the following spring, the compost pile had all but completely disappeared beneath the new growth. It’s now less like a pile and more like a very fertile hill. We pretty much decided to just let it go back to nature and start fresh. But in order to do that, we needed a proper outdoor compost bin!

I asked my husband Ryan about building our own compost bin, and he reluctantly agreed. Between renovations on this old house, building and repair projects for other people, and a plethora of other little side projects he takes on, it’s tough to fit it all in. But we were at a point where we needed this to happen. I couldn’t throw one more slimy banana peel or filter full of coffee grounds on top of the mountain formerly known as our compost pile and feel good about it.

And so, our 3-bin composter was born.

Ryan did some research on the best compost bin for our needs and decided on a 3-bin system. Having 3 bins is so much easier than just one because you have one bin to toss everything into, another bin to mix it and turn it into compost, and a third bin for finished compost that’s ready to use in the garden.

We also wanted to make our compost system completely out of free, recycled materials. Since we were living in an old house that was constantly under renovations, we just so happened to have everything we needed right here on our property:) That’s the beauty of the homesteader mentality!

We used wood from free pallets, fir siding, and shiplap that were a by-product of the renos. Ryan found a piece of corrugated plastic in the lean-to by the garage which he figured would be put to good use as a  lid.

The corrugated plastic piece was 2 ft. x 8 ft, so we decided that our bin would be 8 feet long and 2 feet wide. As far as depth, we decided on 2.5 feet deep since that seemed about the perfect depth to hold a significant amount of compost while still not being too high to get a pitchfork in there and work it. Ryan being the talented handyman that he is, decided to make each front panel removable. Sometimes it can be hard to actually get the compost out of the bin, so this seemed like the best solution to be able to shovel the compost in and out.

For the lid, he built a wooden frame to go around the edge of the plastic so that it would keep it from warping and give it just a little weight. He fastened the lid with some hinges from old doors in our house and then attached a piece of aircraft cable he had laying around to the lid and the side of the bin so that when you throw the lid up and back it doesn’t fall back too far. We were going to use a piece of wood to prop the lid up like you would with the hood of a car, but this was more practical.

As for tools, we used…

• a reciprocating saw to cut down the pallets. (This saw is also known as a “sawzall” because it pretty much saws, well, all of the thing you could ever need to cut. It even saws through nails, which was especially handy when sawing boards off of pallets). 
• a table saw and a sliding miter saw to cut wood into smaller pieces
• a drill/impact driver to piece everything together
• a crown stapler for part of the lid
• a good ol’ fashioned hammer to remove some of the harder-to-get-out nails from the pallets

All said and done, we completed the compost bin from start to finish in one day and it cost us less than the price of a packet of seeds. The only non-recycled material used were the construction screws we used to put it all together – easily found at any hardware store.

If you factor in the cost of the power tools, that would obviously add to the price. But since we had all the tools we needed already, the tools were already paid for and have proven time and time again to be a wise investment for folks like us! (I’m a firm believer in investing in quality things that will last a long time and save money in the long run by costing less per use. Good quality tools are definitely one of those things!)

Speaking of investments, after investing some hot, sweaty work on a beautiful, sunny Sunday afternoon, we now have a pallet compost bin that will surely last us a very long time and help us to produce some amazing, fertile compost to feed our garden with for years to come. It’s official! We’re real gardeners now:)

3-Bin Composter Building Instructions

Below are full instructions on how to build a compost bin like the one we did. Keep in mind that you can amend your bin or design based on the materials you have on hand, so don’t feel like you need to follow the instructions exactly. 

If you don’t have a piece of corrugated plastic to make a lid out of, you could use tin roofing or even a piece of plywood. Or you could forgo the lid altogether if you like! (In fact, you’ll want to leave your lid open at least sometimes when it’s raining so your compost gets a littler water. Water helps the organic material along in the decomposition process.)

If you don’t have pallets but have other pieces of wood that are long enough, use those! Or if you would rather buy wood new, go for it! We just like to do things as frugally as possible whenever we can.

You can change the dimensions as well if you would like it bigger or smaller (or you need to adapt your own bin to the measurements of some materials you are using). But personally, the size and dimensions we went with seem pretty perfect to me as long as you have the space for it.

The point is, feel free to substitute any materials that you have on hand for the best solution for your space, and alter the size or the design if you like as well. However, in order to replicate the 3-bin composter that we built, here are the instructions:

 

Step 1: Prepare Design and Materials

1. Prepare your design and measurements. Here is our compost bin design:

2. Gather all materials you will be using, ensuring you have enough wood. If you have piles of scrap wood laying around like we do, gather all pieces you think you can use. When using scrap wood it’s difficult to say exactly how much you’ll need, but in our case we used the wood from two pallets, two 10 ft. 4×4 posts, and at least 20 shiplap boards, approximately 4 to 5 feet long, plus a bunch of odds and ends. We then milled the lumber we had to the correct dimensions in our schematic, which we’ve included below.  

* Note: If you don’t have scrap wood on hand, you could purchase new lumber, or you could get some free pallets from many local stores. Big box stores always have more pallets laying around than they know what to do with, and are usually happy to give them away for free to anyone who will take them off their hands.

3. Prepare tools and inventory materials (in our case, that meant setting up the power tools, breaking down pallets with a reciprocating saw and stacking materials together).

Step 2: Assemble the Sections of the Bin

1. Cut lumber for the main panels, which will make up the three sections of the compost bin. We used two 4×4 posts cut down to 30”, and six boards cut to 26” -a mixture of pallet boards and shiplap cut to size- to build each panel. We built four panels in total, which made up the two outer side walls and two inner walls that would separate the 3 sections of the compost bin. 

2. Assemble panels. We made sure to leave about 1 1/2″ of space in between each board to allow air to flow through the bin and aerate the compost. (Fig. 1)

Step 3: Assemble the Back of the Bin

1. Once you’ve assembled the main panels, stand them up and space them out according to how wide you want each section of the bin to be. One easy way to do this is to enlist the help of another person, but your panels may stand up on their own. Stand your two outer panels up 96” apart if you’re using the same measurements as us, and then place the two inner panels in between to separate the sections of the bin.

We decided to make the first section larger than the other two because the first section of our bin was the one we would do all the mixing of our compost in. So we made the first section 36” wide and each of the other two sections 30” wide. (Fig. 2)

2. Tie all boards together by attaching boards to the backside of your bin. Ideally, you would have boards long enough to run the entire length of the compost bin, but if you’re using varied or smaller pieces of scrap wood like we did, you can cut boards down to the length of each section to fill in the back sides of the bin. 

Step 4: Build Channels for the Front of the Bin

1. Create channels on the front of each of the 4 posts. The channels will hold the boards in place that will make up each front panel. This is best done with a table saw, so if you’re using hand tools you might want to forgo being able to remove each front panel of your bin. If so, you can just attach the boards the same as at the back, using some construction screws or nails.

To create each channel, first cut filler strips by cutting a 30” piece of wood (we used a piece of 2×6 board), and mill it to a thickness just slightly thicker than the boards you’re using for your removable panels. We used shiplap for the removable panels at the front, so we milled our wood to just slightly thicker than shiplap, or about one inch. Then cut a 30” cover piece for each channel.

Use a board that’s at least as wide as the post or preferably a bit wider. Attach a filler strip to the centre of the front of each post. Then, attach a cover piece to each filler strip. Attach them in the middle so that the gap in between the post and the cover piece creates a channel for boards to slide in and out of on each side of each filler strip. (Fig. 3 + 4)

2. Cut the boards that you’ll be using for your front panels down to size. Measure the distance from one channel opening -filler piece to filler piece- to the next. Cut boards to that length or just slightly less. Slide your boards into place to complete the front of the bin.

Step 5: Build and Attach the Lid

1. Use whatever material you’re using for your lid (if you’re adding one), and attach it with a few hinges to the back of your compost bin. Old door hinges are a good idea because they can handle the weight of a lid. Then attach a piece of chain or aircraft cable (which we used) to the lid and one of the sides of the bin so that the chain or cable prevents the lid from opening too far back. 

 

Last Step: Stand back and marvel at your work!

You now have a brand new pallet compost bin, and you’re well on your way to turning kitchen scraps and yard waste into incredible, carbon-rich material that will feed your vegetable garden for months to come.

Wishing you homemade, homegrown, homestead happiness 🙂

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