Introduction: Double-Decker Drum Composter

Picture of Double-Decker Drum Composter

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

Picture of 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

Picture of 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

Picture of 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

Picture of 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

Picture of 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

Picture of 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

Picture of 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

Picture of 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

Picture of 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

Picture of 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

Picture of 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!


Snow Falcon 12 (author)2017-03-06

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

modrod (author)2010-04-12

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.

Whisperedwoods518 (author)modrod2015-09-26

Can youvsend me the plans for the three barrel system?

modrod (author)Whisperedwoods5182015-10-12

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

forest dancer (author)modrod2011-10-28

do you have plans for this anywhere on the web? I would love to build one

modrod (author)forest dancer2011-10-28

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.

modrod (author)modrod2011-08-25

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.

rhodge-1 (author)modrod2011-03-16

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.

modrod (author)rhodge-12011-03-16

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...

rhodge-1 (author)modrod2011-03-17

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?

modrod (author)rhodge-12011-03-17

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.

aje127 (author)modrod2010-06-25

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.

modrod (author)aje1272010-06-26

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.

iPodGuy (author)modrod2010-06-07

That thing is nuts! Nice work!

brodiemac made it! (author)2015-09-26

Took me a while but I finally finished it.

sedona007 (author)2009-04-27

why is galvanized pipe a "no no"?

wfdixon (author)sedona0072015-01-08

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.)

wfdixon (author)2015-01-08

I love this idea!

joeyisadog (author)2014-03-14

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.

enper (author)2013-10-06

hi iPodGuy,

this seems to be taken from your idea.

alftalavera (author)2013-04-12

Hello friends, I have my rotating compost barrel, say mechanically works acceptably, but beginning to have doubts about its effectiveness beyond being an ingenious and striking.
When green waste burial in a pit in the ground decomposition is very fast and the result has always been good, but this is more work to turn a barrel. With this method I find it hard to find plant debris after a week.
With the rotating barrel took 15 days and I have only a mixture of herbs and plant something muddy, clarified that the mixture contains dried leaves, ground black oak, and ready-made compost.
The barrel has a strainer at the bottom to drain the leachate and in the lateral walls having holes for ventilation.
I think I did my best to build my barrel, I am satisfied with its mechanical operation. Only one thing I do not like is that the tube that operates as an axis, is tangled grass and some like banana peels. If I had to build it again would prevent him having an axis atravezara surely try a bearing mechanism that would stick in the side walls of the barrel.
If anyone interested can share their experience with a barrel swivel I appreciate it, just as I can share all the details of my case.
P.S. If my English seems strange, just tell them you do not master the language, but I do my best. My email is

leander37 (author)2011-04-25

The number of holes seems excessive IMHO. I would be worried about compost drying out. When I build this, I'd think about cutting the number of holes in half. Any thoughts?

iPodGuy (author)leander372011-04-26

Definitely go with less. You can always drill more later if the compost is not breaking down properly.

Half of them clog anyway.

undrline (author)iPodGuy2012-11-14

I guess that answers my question about the top one dripping on the bottom one.

Cestus (author)2012-07-20

What a popular post! How do you get the compost out of the top barrel? Seems like a silly question, but important! Do you use a shoot or slide to get it into wheel barrel?

franciscobolivar (author)2012-06-20

I live in Rio de Janeiro, Brazil and have making compost by the University of California Method (making compost in 14 days) using only grass clippings (nitrogen) and leaves (carbon), with good results.
Did you make compost in your system using only Grass Clippings and Shredded Leaves?
In how many days the compost is ready for using?

Francisco Bolivar

Lorddrake (author)2012-03-01

when the barrel is filling up do you have any problem with distortion around the holes that the axle passes through on the barrels?

if so. would it help adding a support plate inside and out (say 6-8 inches square) so that the axle passes through ... plate | barrel wall | plate .. to help redistribute the load?

iPodGuy (author)Lorddrake2012-03-24

I never had problems with the axle holes distorting. I just went and looked at the bottom barrel (the one I use the most) and even though it's been four years since I published this instructable the axle holes have not warped or bent. They're smoother obviously because they've been rotated on the axle so many times, but it doesn't appear that they've grown any bigger.

55 gallon drums are really strong.

If you're really concerned with your barrels becoming too heavy and failing, you could always add some kind of plate as re-inforcement. If you have an extra drum, I bet you could cut out plastic reinforcement plates, or wood, metal, pvc... It's certainly not going to hurt the design.

Good luck!

BengalTigger (author)2011-10-23

Here is my take on the dual-barrel setup -- a side-by-side. I bolted a 1-1/4 flange on each end of the barrel (flat side out), with PVC pipe adapter screwed inside and PVC pipe running between them as a bushing, and short pieces on the outside as spacers. I ran a single 1" galvanized pipe through the posts and both barrels.

Allen Cham (author)2011-07-15

This is so neat! Ipod Guy, do you think its a good idea for me to put some super dry soil in it too so it fertilizes the soil? Did you need any earthworms or anything like that? and also, do you fill the whole barrel fully with compost or only half full? and is it hard for you to transfer the compost from the top bin to the ground since the lower barrel is in the way?

Sorry its like a whole barrage of question :) great job!

leander37 (author)2011-04-25

For an extra $25 or $30 I'd consider getting an extra drum and cutting a door that would be oversized as compared to the opening. This might alleviate fit/warp/sticking issues.

iPodGuy (author)leander372011-04-26

That's a mighty fine idea.

Layout (author)2008-03-30

My grandfather once made a similar design out of a metal drum. He cut the door out of a second drum and made it larger than the opening. That way you only need two hinges and a latch and the door still holds its shape. Plus it is much easier to open than 4 barrel locks. Great Instructable.

leander37 (author)Layout2011-04-25

Metal is a good idea, but be careful about what was previously in the drum (oil? pesticides? bleach?), and also consider rust as a potential issue.

SGravel (author)2011-03-07

A PVC "sleeve" around any type of metal pipe would solve the problem of potentially leaching contaminants into the soil. It’s an extra step, but you’ll get the best results combining the two materials.

leander37 (author)SGravel2011-04-25

Oddly, PVC may be more "toxic' than any metal that might be used. Steel is predominantly Iron, which is generally beneficial in soils.

tyanger (author)2010-04-14

Nice work.  I just finished a similar project and used input from your design as well as a few others I've come across.  Unfortunately, I didn't document the process well enough to create an entire instructable. Here are photos of my finished product.  I literally just finished this afternoon, so I'm not sure how well it's going to work, or what exact composting flow will work out the best.  I'm pretty much a composting noob.

load_nikon (author)tyanger2010-04-22

 Wow, I like this! What is going on there with the bottom part? I have no idea what I'm looking at here but I really like it.

tyanger (author)load_nikon2010-04-23

LOL.  The bottom is basically just an empty box right now - with a hinged lid and the front panel is 4 slats that slide in/out of slots for loading/turning/emptying.  I kept going back and forth before starting - bin, tumbler, bin, tumbler (not to mention end-over-end vs. barrel roller).  Then after research, it looked like I'd need at least 2 barrels to be efficient - since you end up running batches rather than continuously composting - with a single you might end up with lot's of downtime while one batch cooks.  I didn't feel like I had the right space for 2 barrels (not real keen on setting posts in concrete - or wife wasn't at least)  - so I just stuck the barrel on top of a regular bin.  As of right now I just started a full load in the barrel that I turn daily - I'm not exactly sure what to do with the bottom yet.  I need to decide if it'll be just for storage of the compost from the barrel prior to use or if it'll be a separate operation altogether - more along the lines of a traditional bin requiring turning with pitchfork.

rhodge-1 (author)tyanger2011-03-16

After 35 years as a master Gardener; suggest 'grinding' leaves with a lawn mower or home grinder if money permits and that will take a Lot less room in hte bins and it will "work" faster if the drippings get onto it as well. Microbes will go nuts with moisture and nutrients.
Kept Dry, they will be a Lot easier to load in the barrels Maybe put the barrels at the sides on 2x8 supports attached to bin ?
they would be lower and still could get a wheelbarrow under it to dump it out. Wagon cart plans please!

load_nikon (author)tyanger2010-04-27

 Right On! I love variations on designs. I keep a 55 gallon drum of shredded leaves next to my compost bin and that's what I'd suggest you use the bottom portion for, browns storage.  How tall is this thing? Looks like it would take a ramp to get a wheelbarrow up to the door's level. Heck, at that height, you have room to mount a sifter (rotary or otherwise) underneath.

Check the trommel compost sifter on here for ideas on that, it's an easy easy build and works for so much more than compost. Hey, take a close up shot of that door open, is that bracing or limit-straps?

tyanger (author)load_nikon2010-04-27

The axle (3/4" galvanized pipe) is about 46" above ground.   I just scoop leaves in by hand or a small pitchfork and dump kitchen scraps we've collected temporarily  in an airtight, 2 gal Snapware container, so the height works pretty well.  Gotta look out for the little gnats/fruitflies when I open it up though.  Hadn't really thought about unloading too much - I think I was planning on just pulling the front slats and shoving a wheelbarrow underneath, or dumping into the bin.

That's wood bracing on the lid  - just 2 sections of 2x4 rough cut with a table saw and then shaped a little more with a small block plane.  It doesn't look real good up close (so I'd rather not post a pic, heh heh), but it holds the shape of the lid well.  A band saw or scroll saw would have worked better, but I don't have either.  The hinges and latches are anchored into the wood.

Thanks for the tips.  I have an extra 30 gal barrel I may use to store leaves, or in the bin like you suggest.

iPodGuy (author)tyanger2010-06-07

Spectacular! I like the bottom bin - it will catch everything that falls out of the drum. Great job!

jschmadeke4life (author)2009-08-21

do any liquids drip out of the holes during the decomposition process?

iPodGuy (author)jschmadeke4life2009-09-03

Yes, lots.

AlaXul (author)iPodGuy2010-06-07

I was wondering if the " tea " is good for anything or is it simply waste? Stands to reason that it would have nutrients in it, so add water and water the plants with it. Am I way off base?

rhodge-1 (author)AlaXul2011-03-16

Try a base to hold a 1/2 barrel under one; a sloped surface of what is available to you to drain it to one side into a basin /barrel to collect it. Very good to fee plants with as a watering can tea.

iPodGuy (author)AlaXul2010-06-08

Yep. Water it down and feed your plants.

aje127 (author)2010-06-25

That is BRILLANT. question thou, I don't compost as of yet, so I have no idea how its done, but it is on my list of things to do this year. When you spin the barrel, are you just grabbing the barrel and pulling on it, or are you grabbing the pipe that is running through it and turning that? Also, I'm sure these things get heavy when full, will the area the pipes run in and out of hold up to the weight? (will it rip or tear the plastic?). I love this idea.

iPodGuy (author)aje1272010-10-07

I turn only the barrel. There is a lip on the side that I can grip. You could also add extra handles. Once you get a good turn, centrifugal force takes over and I can spin it with little effort.

It does get heavy, but the thick plastic on the industrial grade barrels does not rip or break. It will hold as long as you use strong pipe.

About This Instructable




Bio: Just your average handyman.
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