The Best Triple Compost Bin





Introduction: The Best Triple Compost Bin

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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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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.


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?

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!

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.

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.