Double-Decker Drum Composter




About: Just your average handyman.

Composting is easy and fun. Kitchen scraps, leaves and lawn clippings are allowed to decompose naturally and they become a healthy, nutrient-rich and beneficial soil for the garden.

In this instructable, I will show how I made a spinning double drum composter to make soil for my garden.

Step 1: Making the Frame

I decided against documenting every step with building the frame, mainly because it's a simple enough design.

The frame consists of 3 pressure treated 4x4's and 1 pressure treated 1x4, all eight feet long. One 4x4 was cut exactly in half and the 1x4 was cut into quarters - they were to become the 2 beams and 4 stakes.

I drilled pilot holes through the posts and into the beam and held them together with galvanized lag bolts. Each of the corners where the beam meets the post got corner braces and the top got flat braces. The braces are meant for extra support, since the barrels may become heavy. The space between the top beam and bottom beam was 3 feet.

I used a 2 inch hole saw to cut holes into sides of the posts so they can hold the poles later on.

Then, I used some exterior screws to fasten the stakes to the bottom of the posts. The entire frame gets cemented into the ground later and the 4 stakes offer additional support to the frame.

At the bottom of the posts and stakes, I drilled some screws partially into the wood to hold them into the cement better.

Step 2: Installing the Frame

After the frame was complete and I decided where it was going to go, I dug two trenches for the posts and stakes to go into.

Step 3: Installing the Frame

After I dug the holes and set the frame into place, I filled the holes with fast setting cement. Each hole took 6 bags (12 total - 60 lbs. each).

Once the barrels are made and full, they could get very heavy with the compost so the frame and concrete anchors must be strong. I feel as though the stakes and concrete will prevent the frame from leaning or moving much.

Step 4: The Barrel Poles

I used galvanized poles left over from another job and cut two 5 foot lengths. These go through the holes in the posts and are what holds the barrel.

Be careful when selecting poles, since they will need to be strong to support the weight of the barrels when they're full.

Step 5: The Barrels

Once the frame was ready, I began working on the barrels which are made from 55 gallon drums.

I decided to use blue since they get warm and will heat the compost inside. The barrels need to be a dark color since light colors will reflect the sun and heat is important when composting.

Using a 2 inch hole saw, I cut holes exactly in the center of the bottom and top of the barrels. This is what the pole will go through.

Then, using a rotary saw, I cut a rectangular door into each barrel. Take care that the door is big enough to allow comfortable access to the inside of the barrel.

After that, I used a drill to drill several hundred holes all over the barrels to allow for air to circulate inside the barrel. Air is also important when composting.

Step 6: Tha Barrels

To make the door, I had to get several pieces of hardware.

I needed 2 flat braces, 2 handles, 4 hinges, 8 barrel locks and enough screws/nuts/washers to hold everything on.

Each door got 4 barrel locks since they work together to hold the door closed while spinning and they help to keep the shape of the door, since they tend to lose their shape and flatten out.

Each barrel also got a flat brace installed inside. It sticks up slightly to prevent the door from falling inward.

Step 7: The Barrels

Now that the barrels were finished, I put the pole through the barrel and put them on the frame.

I checked everything and made sure that the barrels spun on the poles properly.

At this point, the project is complete.

Step 8: Using the Composter

Making compost in the barrels is easy. Simply throw all kitchen scraps, lawn clippings, leaves and other organic matter into it and it will decompose naturally and make healthy soil.

Once one barrel is full, the next one can be started on. Rotate the barrels every so often to mix and aerate the compost.

***Take care not to put things like meat and animal feces into the the compost - only vegetables and plants. However, one exception to this would be eggshells. If unsure, do an internet search on composting to find lists of acceptable materials.***

Step 9: Optional (but Helpful) Hint

This step is purely optional, but I don't want to have to make a trip out to the composter every time I make something in the kitchen, so what I do is keep a little plastic bin in my freezer. I put everything in there and when it gets full, I dump it into the composter. It melts and decays right along with everything else and saves me a few trips.

Step 10: Summary

I really had a good time making this project. It was easy enough and the design was quite simple. Now, by next spring, I should have some great compost for my garden so I can grow some healthy plants.

I can't wait for spring to come on full-force!

Step 11: User Photo Gallery

Big thanks to everybody who made their own double-decker drum composter and submitting their pictures!

They look fantastic and I'm thrilled that you took the time to share!

Participated in the
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2 People Made This Project!


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309 Discussions


Question 2 months ago on Step 1

Do you know what kind of wood you used? Do you believe the kind you used is very sustainable or has been? Has it suffered any erosion over the past couple years?


Question 2 months ago on Step 4

What kind of cement did you buy? And how did you go about laying that? I am highly interested in this project but am not sure where to get the cement and what kind.

Snow Falcon 12

2 years ago

may i suggest making it a tumbler as well as a composter


9 years ago on Introduction

Great Instructable. Last year I expanded on the concept and made a three-barrel, rotating composter where each barrel spins independently and the entire unit rotates to make unloading more easy. I'm still perfecting it and have learned a few things: If an empty barrel ends up on top, it takes a big effort to rotate the two full barrels to the top. I'm thinking of some sort of crank device but with at least two of the barrels cooking at any one time, it's difficult to do that kind of work to the unit. Still works quite well.

I started with lots of air holes, which proved to be too many for our desert climate, so I filled most of them. The down side to that was that during our very wet winter (unusual) the compost batches got too wet and stopped cooking for a while. Now that it's dried out somewhat, everything seems to be working well again.

12 replies

Reply 3 years ago

Sorry, there were never any plans. I just made sketches on scrap paper, which I eventually recycled.

modrodforest dancer

Reply 7 years ago on Introduction

Not really, just some rough sketches I made based on the original, double decker Instructable and other ideas. The only differences between mine and the double are the main axle and spokes, which are welded to a small piece of tubing at the center.

Sorry I don't have more. I didn't take photos as I went along, so in order to do a Instructable correctly, I'd have to build another one. That isn't feasible at the moment.


Reply 7 years ago on Introduction

Just a quick update on my knockoff. Yesterday, one of the individual barrel axles broke, due to being rusted. I didn't use galvanized to go through the inside of the moist barrels, just some steel tubing I had left over from other projects. It's the bottom barrel in the photo. I'm now in the process of replacing that one and the other two. Other than that, it still works great.

On the spinning issues, I've found that making sure all barrels are full, at some stage of compost, really helps when turning the whole thing.


Reply 8 years ago on Introduction

Gear the main shaft with a Large gear and the drive gear (or two) from a gear speed reduced motor that is fairly cheap at about $50. that will turn those on a 1/3 hp or up to 1./2 hp with all full.
About a 10 to 1 ratio maybe?
I got one of those second hand for $10. Was 1/2hp.


Reply 8 years ago on Introduction

Interesting idea but a little overkill for this application. I've found that my rotation problem goes away if I just keep all three barrels full. :)

I have discovered that iPodGuy's original design for the doors is better than what I did. The plastic doors, at least one of mine, has warped a bit and I'll have to reposition one of the locks in order to get it to seal better. Not a big deal...


Reply 8 years ago on Introduction

For the doors warping; I had occasion to put steel strap around the plastic of one I made years ago and that stopped the plastic warping; used Pop Rivets with inside washers for that.
Maybe add slide screen locks at a couple of other points to spread the load to stop materials pressing outward too hard? What do you think?


Reply 8 years ago on Introduction

That's probably a good idea on the steel strap. Thanks for that for future reference. I do have two slide locks per door and will either move the one that doesn't line up or add another as needed.


Reply 9 years ago on Introduction

Dude that is AWESOME. I have a huge yard that has a BIG veggie garden and then an insane landscape flower and fruit garden. I would be really interested in how you did this and if you fixed your rotating issue.


Reply 9 years ago on Introduction

Nope, haven't addressed the rotating issue yet. I've just been man handling it. I did recently empty out one of the barrels and rotated everything around. Didn't seem so difficult this time, maybe because the bins weren't really overly wet at the time.


Reply 4 years ago on Step 4

metal has a zinc coating. Questions have been raised regarding the safety of zinc. The coating on these pipes may also have cadmium which is dangerous. (Do a search for toxic effects of zinc.)


5 years ago on Introduction

the quality of your composter is great. Looks very strong. When you move out of that house they'll make it a swing set with the framing that'll last for decades... :)

However, if those are oranges in your compost i recomend not composting them because the citric acid with throw-off your ph and could kill or inhibit good bacteria, etc.