Rodent Resistant Composter

 by mollyd
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This is the easiest and cheapest composter design we've come up with for keeping rodents out of our compost.  We made the traditional compost bin out of pallets but rats crawled through since we didn't line it with mesh.  Instead of building another pallet bin and lining it with mesh, we skipped the wood all together and built a cylinder of mesh.

The composter consists of two parts: an outer basket containing wood chips and an inner cylinder of compost that is always topped with carbon material and a mesh lid if we're really worried about critters.

The outer ring of wood chips surrounding the compost chamber insulates the compost, absorbs any smell from the compost and makes it harder for critters to reach the compost.  Who wants to bite through wire mesh and then crawl through a foot of woodchips to eat rotten fruit?  Hopefully no one. Not even you, neighborhood possum.

The inner ring of compost has decomposed very fast, it sinks about a foot every two weeks. The woodchip area is also full of mycelium and a mushroom or two pops up every month.

Our last composter (pictured with me here) also featured a fan to aerate the compost using a solar hot air collector.  You can check out more about our composting experiments at our blog for decentralized waste management strategies.

We also have a temperature probe in ours (see blue cord) to see how hot it is.
 
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Step 1: Equipment and Materials

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To build a 4' wide composter with a 2' diameter inner cylinder that's about 3' tall you'll need:

 12.5' x 4' quarter inch galvanized mesh or as the hardware store calls it "hardware cloth"

3' by 6.28' mesh or fencing to separate inner compost chamber from woodchip insulation.  (we found old 4' wire fencing)

2" or longer wire pieces to piece mesh together (or zip ties)

measuring tape

wire cutters (it's such a pain to do this if you don't have good wire cutters)

pliers

Composters need to be big enough to allow the material to get hot and stay hot.  This can be achieved by building an uninsulated composter that's 1 cubic yard or it can be samller if it's insulated to keep heat in. 

Size of mesh needed for Smaller composter that's only 3' diameter with inner basket of 1'. For this one the composting chamber is only 2' in diameter but it's insulated on all sides by 1' of woodchips. My drawings refer to dimensions for this smaller composter.


7' by 4' of quarter inch galvanized mesh for outer compost container

3' by 3.14' cheap mesh for inner cylinder

Why make a smaller one? Because space is expensive.
caponet4 says: May 11, 2012. 3:27 PM
Nice work! maybe you want to consider saving the juices that come out, that's a fertilizer too. I think that raising this thing a few inches and with a convenient "open-close" hole on the bottom, you wouldnt have to bother on tiping it over/ empty the thing. My composter configuration consists of 4 buckets stacked with holes, the worms live in the lower one, when they're done I simply stack the bottom one to the top of the stack.
Having cats arround can help with the mice thing.
Also beware that compost can raise up the temperature and this could kill the gourgeous comunity that lives there, but I imagine that this is not the case couse of the mesh. Cheers!
Skip says: Jun 25, 2010. 2:20 PM
thats all well and good, and I really like the idea of a double composting system, but how do you get the composted materials out when you're done?
mollyd (author) in reply to SkipJun 25, 2010. 3:35 PM
So true. We started our pile in February and emptied it in May to investigate, but the compost wasn't finished yet. We turned it a bit and put it back together. To open it unclip the zip ties or wires holding the side of the cylinder together and dig out the materials. Or if you'll feeling roudy you can try to tip the thing over on it's side and let it spill over. I think it will be a total of 8 months before our compost is completed and ready to take out.
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