The Best Triple Compost Bin




Introduction: The Best Triple Compost Bin

About: I am the monthly DIY/crafts writer for the Santa Cruz Sentinel. You can access an archive of all my columns at

Instructables has plans for several compost bins made from recycled products like garbage cans and pallets.  I've used a black plastic orb for composting, but it gets too heavy to roll around as it fills up with moist material.  I wanted to make a sturdy bin that was easier to use, would not compost itself, and could accommodate more waste, without spending too much on materials.  Wooden compost bin plans often call for pressure-treated lumber, but I don't like the idea of pesticides in the lumber leaching into my compost and soil.  So I decided to use recycled redwood, which I had in abundance from a play structure we built for our kids when they were young.  Redwood (west coast) or cedar are the best choice since they are rot-resistant, and will keep the garden organic and safe.

Although the triple bin uses lumber, the sides are made from wire hardware cloth, so this cuts down on the expense of using all wood.  You'll need a 3x9 foot space in your yard to accommodate this bin.  The large size will allow you to compost everything you've got--from garden trimmings to kitchen waste.  Ours is in the garden but not too many paces from the kitchen door, to make composting as convenient as possible.  The triple bin will also allow you to compost in stages, moving the contents from one bin to the next as the material breaks down.  With removable wooden slats in front, the compost is very accessible and easy to turn, stir or shovel to the next bin or the garden.

Step 1: Materials & Tools

DIVIDER FRAMES: Four 12-foot 2x4s (cut into eight 31-1/2-inch long pieces and eight 36-inch long pieces)
TOP AND BASES: Three 10-foot 2x4s (cut into three 9-foot pieces)
FRONT RUNNERS: One 12-foot 2x6 (cut into four 36-inch long pieces)
INSIDE RUNNERS: Two 10-foot 2x2s (cut into six 34-inch long pieces)
SLATS: Six 8-foot 1x6s (cut into 18 slats, each 31 1/4-inches long)

One 25-foot roll of 36-inch wide 1/2-inch hardware cloth (cut into four 37-inch lengths, and one 9-foot length)
2 lbs. 16d galvanized nails
One box poultry wire staples (about 250)
Twelve 1/2-inch carriage bolts, 4 inches long with washers and nuts
Two quarts clear shellac and paint brush
(Optional lid: exterior plywood cut into three 3 x 3-foot pieces and attached to the back with six hinges)

General wood-working tools are needed such as:
circular saw
tape measure
carpenter's square
socket wrench
wire cutters
drill with 1/2-inch bit
paint brush

Step 2: Divider Frames

  1. Butt-joint and nail two 31 1/2-inch pieces and two 36-inch pieces into a 35-inch x 36-inch square. Repeat, building three more frames.
  2. Fold back the cut edges on each piece of hardware cloth 1 inch.  Center each piece of hardware cloth on each frame.  Make sure the corners of each frame are square before stapling each screen tightly into place every 4 inches.  The wood-and-wire frames will be dividers for each section of the bin.

Step 3: Top and Bases

  1. Set two dividers on end with the 36-inch edges on the ground, 9 feet apart and parallel to one another. Position the other two dividers so that they are parallel to and evenly spaced between the end dividers and each other. (Each divider should be about 31 1/2 inches apart to accommodate the 31 1/4-inch long slats.)
  2. Place two 9-foot lengths of 2x4 across the tops of the dividers so that each is flush against the other edges.  Measure and mark on the 9-foot boards the center of each inside divider.
  3. Through each junction of board and divider, drill a 1/2-inch hole centered 1 inch from the edge.  Secure the boards with carriage bolts, but do not tighten yet.  Turn the unit right-side up so that the long boards are on the bottom.
  4. Attach the remaining 9-foot 2x4 to the back of the top by repeating the process used to attach the base boards.  Using a carpenter's square, make sure the bin is square, then tighten all the bolts securely.
  5. Fasten the 9-foot length of hardware cloth to the back side of the bin with staples every 4 inches around the outer and inner frames.

Step 4: Front and Inside Runners

  1. For the front runners, nail a 36-inch long 2x6 to the front of each outside divider and baseboard, making them flush on top (not as pictured in photo) and outside edges.  
  2. Center the remaining two 2x6 boards on the front of the inside dividers, flush with the top edge (not as pictured in photo) and overlapping about 1 inch on each side, and nail securely in place.
  3. For the inside runners, nail each 34-inch 2x2 to the insides of the dividers so that they are parallel to and 1 inch away from the front runners and flush with the top edge (as pictured).  This creates a 1-inch vertical slot on the inside of each divider, which allow you to easily slide the slats in and out.

Step 5: Slats

Insert the 1x6 boards into the vertical runner slots, up to six per bin. Paint all untreated wood with shellac.

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21 Discussions

Would shellac not add toxicity to the compost? Also, what is the size of the carriage bolts? I did not see that on the supply list.


1 reply

oops...just saw the carriage bolts info. I overlooked it.

This is great - thank you! I need a lid on mine due to rats in our downtown 'hood. Any suggestions?


2 years ago

This looks so fab. Just wondering if anyone can help me as I've been puzzling over this for the last few hours! Would anyone tell me how to make this into an all-wood construction? In my climate it would be too cold for the wire sides...what changes would I need to make in wood sizes and amounts to give it 4 wood sides each? :-/ I'd only need one side of each pod to be slated, the others could be fixed in wood... anyone better at DIY than me greatly appreciated! :-D

Excellent instructable! I've made compost bins out of old pallets and they were very time consuming, difficult ( if you want it done right) and costly (hardware). The only suggestion I would make would be using screws in place of nails and a simple tarp would work for a lid. Thanks!

I made this compost and I wanted to say a huge THANK YOU for posting with such tremendous detail. I only did a double wide (not triple) due to size of our yard and garden, but your instructions made it possible to easily customize for my needs.

This has been the best project of my year -- maybe even life. Thanks so much for taking the care to make it easy to follow.

One question -- would you recommend I remove the grass underneath where I plan to to put the compost bin? Or should I line it with plastic on the bottom or something? Anyway, thanks!

1 reply

Another modification I made was that I used old crown molding for the removable slats, so I made the gap 1/2 inch instead of 1 inch.

I used all scrap wood or wood purchased at Habitat Restore. Same thing for the hardware: got great deals at Restore. The only thing I had to buy new was the landscapers cloth (chicken wire) and some nails, so in all the project cost me less than $50..

I can't tell you how many times I referred back to your images -- they were great!

compost photo.JPGcompost photo.JPG

We compost autumn leaves, which make for a huge compost volume into which kitchen waste is a small added percentage. Problem is, it's hard to turn over that much, and worse, tree and vine roots grow up through any plastic-sheet ground-liner bottom. I would suggest for such large needs searching for the discarded lower half of a thousand-liter-plus storage tank (usually fiberglas) as a more-easily workable environment for cubic-meter-plus volumes of compost.

4 replies

Don't compost the leaves in a bin -- grind them up / wet them down and then pile them along a fence row to make leaf mold. It will take a full year, but it's pretty much effortless. Add leaves to the compost pile only as you have green wastes to match with them. Once the C/N ratio gets out of whack either the pile slows to a crawl or it turns anaerobic and stinky.

I save autumn leaves (actually the neighbors bag them up for me!) until I have grass clippings to go with them. I usually end up with more compost than I can actually use (wisely).

. . . To JustBill
. . . This is a semi-tropical climate, with acidic soil, rendering most of your statements inapplicable here. Depending on the leaf type, leaves in Houston decompose to half-life within three months (assuming normal 40"/yr. rainfall or watering). Earthworms and insects are prolific here and speed decomposition. Therefore, the added expense of mechanically grinding leaves is both inappropriate and unnecessary. Your advice, piling leaves along fence rows assumes (false in my case) you don't have airborne tree seeds such as hackberry trees and weed seeds, or aggressive weed vines and tree roots that spread underground and grow up into compost from below. Hence, I recommended a simple giant tank-tray isolation container, maybe with a screen-mesh over the top to keep seeds out. Drilled tank-drainage holes would also need screening against root-invasion.
. . . You may wish to describe for newbies in greater details about C/N ratio and natural sources adding to kitchen-refuse (e.g., composting septic tanks). Besides nitrates, "seeding" new compost with a thin mix of natural topsoils or old compost infectiously speeds decomposition.
. . . Years ago I worked in a truss-mfg. mill where they cut and assembled wood, generating huge volumes of sawdust. I bicycled home with a couple cubic feet of it bagged daily, covered my front yard a foot deep (after first hoeing off the bermuda grass and weeds an inch deep and baking the resulting mound under black plastic sheeting for six months to sterilize it), added nitrate granular fertilizer, and it decomposed to 1/3 that height, soil in six mo. I initially grew wandering- jew ground-cover and giant elephant ears with added seasonal wildflowers, papaya plants, and mimosa trees within a half year.

The various responses to what I posted just indicate that local conditions vary considerably. Neither your recommendations nor mine are worth much in the arid adobe soils of the desert southwest. But there are techniques that work even there. Neither of us have addressed high-altitude composting or sandy / saline soils. That's not what this 'able is about.

I think that the bottom line to most soil problems is "more compost". I add my amendments in the spring, work them about 2" deep, plant and then mulch like crazy after everything is up. 4" in the spring pretty much disappears by mid-summer, when I'll give it another 4-6", depending on how much compost I've been able to make. I try to make two piles in late summer and leave them both for use in the spring.

The mechanical grinding to which I referred requires nothing more than a rotary lawn mower set to a high cut height and a wall to direct the discharge toward. Most (but not all) home owners already have this machine and thus it represents no expense beyond fuel of some sort. One of the reasons for this grinding / chopping is to reduce its bulk. By the time the trees around here drop their leaves, grass clippings are in short supply so I bag as many leaves as I can store unobtrusively and then fence row the rest. The city thinks that a compost pile (at 135 deg +) is rat harborage and worthy of a $500 fine and 10 days in jail ... but they never even notice a 3' tall pile of leaves.

I have a question for you:
When you solarized your lawn, why did you use black plastic instead of clear? My understanding is that higher temps are obtained under clear plastic (such as visqueen). Not trying to be rude ... just trying to add to my toolkit.

. . . Thank you for your reply. True, climate, soil type, size of compost pile, and other factors all must be considered for optimal results. I thank you for sharing additional insights. Go, earthworms. go!
. . . In response to the question of which is hotter for ground cover (black plastic or clear), I can only say my main consideration was denying the leftover bermuda grass and weeds any light whatsoever. This was a long mound of mixed clay topsoil and vegetation, which I had hoed off the remainder of the yard before covering the yard with sawdust a foot deep and sprinkling granular fertilizer on it. Some plants, like elephant ears and wandering jew vines, can grow in this very soon, given ample rain or watering. Meanwhile, several months of hot dry darkness under the black plastic seems to have worked on the mound; when uncovered, through sifting all the soil, I found only one small strand of bermuda grass tuber left alive.
. . . With a low wall of interlaced stacked bricks by the curb (to keep stray dogs out), and the addition of mimosa trees, papaya seeds, and wildflower plants and seeds collected from across Texas in trips to bicycle races, I was rewarded with a front yard that looked different each month as seasonal flowers or melon vines bloomed, and it never needed grass mowing! I never bought pesticides or weed-killers, either, as I calculated the cost to be greater than the minor hour's time of my labor removing them in inspections every other day.
. . . Houston is a semi-tropical climate, averaging a dozen days of freezing lows per year, but continues into in 2011's September to have a record drought (1/3 normal yearly rainfall). 30 of 31 days in August we endured temperatures of 38°C. (100°F.) or greater, topping out at 43°C. (109°F.) to tie our all-time record for this near-coastal city. Tropical storm Lee gave us insignificant sprinkles. Outdoor watering is now being rationed. I have no additional comments to add to this thread.

One of the coolest comp bins I have seen. Seems easy to put together. This lady should be a winner have my vote!!!!!

Nice bin and instructable. What about the top cover? Rain would wash away all the good stuff out of the compost

3 replies

I usually heap my compost. You can just cover with a tarp when it rains, or when there is too much sun for that matter.

Well, I mention the lid as optional in the materials section. I didn't know the good stuff could wash away.

I hope people give 2 story composters (one on top of another) a try. Rather than turn the compost, you just pull it from one story into a hole that leads to the lower one, gravity does the work so it is easy. If you has a suitable place you could do a 3 story composter too.

It takes a LOT of rain to wash the nutrients out ... most places don't even get enough to replace the water lost by evaporation ... and then it's a simple matter to collect the run-off with some sort of drip pan. Voila! ... instant compost tea.

This pile is the minimum size recommended. Better to use a 4 ft cube, if possible. It holds heat and moisture better than a 3 ft. cube but isn't so heavy as to force an anaerobic pile. Use the same design, but make the overall dimensions 4' x 4' x 12' if you have the room.

Good to know. I guess when you add water to your compost to keep it moist you shouldn't dowse it with a heavy stream of water then--just a fine spray?