How to Build a Wood Compost Bin
Constructed compost bins can make an attractive addition to the garden while containing composting operations. There are quite a few compost bin designs available in manuals and on websites. While these may all vary in small ways, the plans tend to share similar features — a wooden frame with wood slats, chicken wire or hardware cloth. In this article we break down some important considerations when planning to build your own homemade compost bin and share some of our favorite DIY compost bin plans.
How many compartments?
Rather than building one square compost bin, some plans call for a large, rectangular frame that is divided into two or three smaller square compartments. Having two or more compartments is a helpful way to separate compost by stages of decomposition. When one compartment becomes full of ingredients, move on to the next compartment. Continue to keep moist and turn regularly.
Over time, the contents of the first bin will decompose and lose a lot of mass. It’s normal for a compartment that was full before moving to the next compartment to start to looking pretty spare after a few weeks. That means that the decomposing organisms that live in the bin are doing their jobs! When the compost in the compartment is finished, harvest and use in the garden, and start the process all over again.
Two or three bin systems are also handy for gardeners who may not generate enough composting ingredients to keep more than one bin going through the year. Rather than using all the compartments for active composting, one compartment could be used to hold bulky materials, such as wood chips, straw, or manure, to add to the active compost compartment as needed.
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Wire vs. Wood?
Some plans call for walls made of chicken wire or hardware cloth, while others require loosely spaced slats of wood. Both do effectively keep in the bin and allow some ventilation.
Wooden walls tend to be more expensive than metal. Many lumber yards will pre-cut planks to the sizes specified on your plans – however, these cuts may not be as precise as you could do at home. The ventilation spaces between the slats allow rodents and other critters easy access to the compost, which is especially undesirable for folks who live in the city or suburbs.
The same organisms that make compost happen will also deteriorate the wood. Avoid lumber that has been treated with creosote or arsenic, because these toxins can leach into the compost, then into the plants the compost will feed. Rot-resistant lumber, like cedar,will last longer than other untreated woods, but it will also be more expensive; avoid using treated lumber, which can leach chemicals into your compost and garden. After building the bin it may be worthwhile to treat with a water-sealing product. Or simply replace rotten planks as necessary.
Wire mesh is typically less expensive than wooden slats, and it can last longer than untreated pine boards. Look for galvanized steel or vinyl-coated products, because they’ll resist rust longer than other meshes. Mesh walls are more effective at deterring rodent pests than wood walls. If you prefer the look of wood, but want to deter varmints, consider lining the inside walls of the wooden bin with wire mesh instead of choosing one product or the other.
Your bin should be large enough to contain the yard and kitchen waste you generate, but there are other factors to consider as well. If you want to do “hot” composting that will kill garden pests and plant diseases, each compartment should be able to hold a pile that is at least 3 feet tall and 3 feet wide. Regardless of method, your bin should be large enough for you to maneuver when turning the compost with a pitchfork.