Interested parties are encouraged to Google the benefits of a three-stage composting system: you'll come up with a huge, steaming pile of expert testimony, along with copious shovelfuls of plans far better than this one. There are versions out there made of pallets, wire mesh, steel paneling...
Our composter is built using the cheapest (non-treated) wood we could find, and is designed with chickens in mind: should they try to hop up on the slanted roof and jump the fence, they will fail hilariously. The front panels are removable to allow easy critter access, and the lids (roofs?) stay open for easy human intervention.
Note: I entered a Photo 'ible version of this one in the "Garden" contest: if you are so inclined (and if it remains eligible), please vote here: http://www.instructables.com/id/Chicken-Powered-Three-Stage-Compost-Bin-Photos/
Step 1: Tools, Materials
Driver/drill & bits
Of course your mileage will vary but this materials list should give you an idea:
|2"x4"||10'||6||Base, front verticals|
|1"x6" Fencing||6'||32||Back, sides, front|
|1"x1"||10'||3||Rails to hold in front panels|
We stuck with inexpensive, non-treated pine and fir.
Step 2: Base & verticals
Place 2 - 9' 2x4s beside each other, and cut two 29" 2x4s for the ends (2x4s are actually 1-1/2" x 3-i/2" so your small sides will be 3' minus 7", which is 29"). Long nails or screws.
Next, make four trapezoids: mine had 3' bases, 30" fronts, 4' backs, and the slanted "roof" angle ended up being... whatever it ended up being: which was pretty close to 3' long... but all I did was lay the "roof" 2x4 from the front to the back,and drew the angle with a pencil (not very precise, but adequate for backyard construction). Nail or screw the "frame" together.
Once the first trapezoid is complete, clone it thrice for a total of four (yes, you read right- I I actually said "clone it thrice." So sue me!).
Convince the trapezoids to stick vertically to the base, 3' apart. Ask a friend to help. A few nails and/or screws is enough. This part will still be a bit wobbly for now, and that's okay.
Step 3: Back & Sides
Fill in the back with fence boards. I chopped a bunch of 6' boards in half, so each row across the back is made of a 6' and 3' length.
Fill in the sides with fence boards. For the angles I just held up fence bits and drew the angles with a pencil, but one could get more precise if one were so inclined.
The whole structure becomes quite sturdy once the siding is applied.
Step 4: Rails & front panels
Cut boards about 1/2" shorter than the width of the bin, and slide them in!
This design allows boards to be removed as needed to allow a chicken (or two or seven) to do their work, regardless of how deep the compost pile happens to be.
Step 5: Lid/Roof
Cut the 12' panel into four pieces, each 3' long by 2' wide. Then cut one of the 3' sections into 3 one-foot sections, and add a 1-foot section to each 2' piece: that makes three 3' roofs!
Make a "U" shape out of 2x2 that fits the size of the first bin: flush on the left side, and ending halfway onto the angled 2x4 that defines the pitch of the roof. Add an additional strip of wood to make a square out of the "U" (see photo).
Slap it together with screws, and attach it to the horizontal 2x4 at the top, using strap hinges.
Cut two identical strips of wiggle-board to fit the upper and lower edges of the roof, and tap in a few short screws to hold them in place. Fit the fiberglass onto the wiggle-board, overlapping as needed to make one 3' roof out of your 2' and 1' pieces. Secure all around with wood screws. If possible, use the self-tapping screws that come with their own pre-installed rubber washers, because those are extra cool and weatherproof.
Repeat for the other two lids, taking care that they all can open & close without bumping into each other.
Step 6: Add Compost & Chickens
Manage your compost in three stages- keep the roof closed for greenhouse-effect heating, let your chickens do a whole lot of the heavy lifting, and enjoy your vastly improved compost!
Note: Watch this 'ible over the next few weeks- as the composter gets into full swing, I'll post some images of our chickens in action!