A pallet compost bin costs almost nothing and takes a few hours to build

A pallet compost bin is a wooden box made from shipping pallets that holds kitchen scraps and yard waste while they break down. You stack four pallets into a square or rectangle, find them at the corners, and line the inside with wire mesh to keep rodents out. The whole project costs between $0 and $30 depending on whether you find free pallets, and you can finish it in an afternoon with basic tools.

The main advantage is cost: pallets are often free from warehouses, loading docks, or online marketplaces. The main drawback is that wood pallets rot over time, usually lasting three to five years before the bottom boards need replacing. If you want something that lasts longer, a plastic bin or metal cage is more durable, but a pallet bin is the cheapest way to start composting.

Key Takeaways

  • You need four pallets of the same size, wire mesh or hardware cloth, wood screws, and a drill or screwdriver — most people already own these tools.
  • Free pallets come from warehouses, garden centers, and Facebook Marketplace, but inspect them for chemical stamps or damage before taking them home.
  • The bin works best in a spot that gets partial sun and drains well, away from your house if you want to avoid fruit flies and odor.
  • Line the inside with quarter-inch hardware cloth stapled to the wood to block mice and rats from burrowing underneath.
  • The bin fills from the top and you remove finished compost from the bottom by pulling out the front pallet or leaving a gap when you build it.

Finding and inspecting pallets

Pallets are stacked outside most warehouses, garden centers, and loading docks. Ask the manager if you can take them — many places want them gone and will say yes when ready. Check Facebook Marketplace, Craigslist, and Nextdoor for people giving them away. Some hardware stores and grocery stores also have free pallets, though they may ask you to come back at a specific time.

Before you take a pallet, look at the top surface for stamps or markings. A stamp that says "HT" means it was heat-treated and is safe to use. A stamp that says "MB" means it was treated with methyl bromide, a pesticide — do not use these for compost that will touch food plants. Avoid pallets that are visibly rotted, cracked, or stained with unknown liquids. Pallets from food suppliers are usually safe; pallets from chemical or machinery suppliers are not.

You need four pallets of the same size. Standard pallets are 48 inches by 40 inches, which makes a bin roughly 4 feet by 4 feet. Smaller pallets work too, but the four must match so the corners line up evenly.

Tools and materials you will need

Gather these items before you start:

  • Four pallets of matching size
  • One roll of quarter-inch hardware cloth or wire mesh (at least 16 feet long)
  • Sixteen wood screws, 3 inches long, rated for outdoor use
  • A drill with a screwdriver bit, or a manual screwdriver
  • A staple gun and staples, or a hammer and nails
  • Work gloves and safety glasses
  • A tape measure
  • A utility knife or tin snips to cut the wire mesh

If you do not have a drill, you can drive screws by hand with a screwdriver, but it takes longer. A staple gun makes attaching the wire mesh much faster than a hammer and nails, but either works. You can buy hardware cloth at any hardware store or online for $15 to $25 per roll.

Building the frame: step by step

Lay the four pallets flat on the ground in a square or rectangle, with the edges touching. Stand at one corner and look at how the pallets overlap. You want to screw through the side of one pallet into the end of the next pallet, creating an interlocking corner.

Drill a pilot hole (a small starter hole) through the side of the first pallet, about 2 inches from the corner and 6 inches up from the ground. Drive a 3-inch screw through that hole into the end of the next pallet. Repeat on the other side of the same corner, then move to the next three corners. Use two screws per corner — four corners times two screws equals eight screws. You now have a sturdy frame.

If your pallets have a top deck (the boards you see) and a bottom deck (the boards underneath), the frame is stronger if you screw through the thicker parts. Most pallets have three or four stringers (the support beams running perpendicular to the deck boards) — aim your screws at those.

Check that the frame is square by measuring corner to corner. Both diagonal measurements should be the same length. If they are not, push the corners until they match.

Lining the bottom with wire mesh

Rodents will burrow under the bin if you do not block them. Cut a piece of quarter-inch hardware cloth large enough to cover the inside bottom and extend 6 inches up each side. Lay it flat on the ground inside the frame.

Use a staple gun to fasten the mesh to the bottom boards of the pallets, spacing staples about 4 inches apart. Fold the mesh up the sides and staple it to the inner walls, overlapping the corners. The mesh does not have to be perfect — small gaps are fine. The goal is to make it hard enough for a mouse to chew through that it gives up and goes elsewhere.

If you do not have a staple gun, you can nail the mesh down with short nails, but it takes longer. Wear gloves when handling the mesh — the cut edges are sharp.

Positioning your bin and finishing touches

Place the bin in a spot that gets at least a few hours of sun each day. Compost breaks down faster in warmth. The ground underneath should drain well — if water pools there after rain, move the bin to higher ground or add a layer of gravel underneath.

Position the bin at least 3 feet away from your house if you want to reduce fruit fly and odor problems. If you have a large yard, 10 feet is better. Compost that is actively decomposing can smell strong, especially in summer.

If you want to remove finished compost easily, leave the front pallet unattached so you can pull it out. Screw the other three sides together, then rest the front pallet in place without fastening it. When the compost is ready, lift out the front pallet and shovel from the bottom.

Alternatively, you can attach all four sides and remove compost by reaching in from the top, which works fine for smaller batches.

What to put in and what to avoid

Layer green materials (grass clippings, vegetable scraps, coffee grounds) with brown materials (leaves, shredded paper, straw) in a ratio of roughly one part green to two parts brown. Avoid meat, dairy, oils, and diseased plants. Do not add pet waste or treated wood chips.

Keep the pile moist like a wrung-out sponge. If it smells like ammonia, add more brown material. If it is not heating up or breaking down, add more green material or turn the pile with a pitchfork.

A pallet bin typically produces finished compost in six months to a year, depending on how often you turn it and what you add. If you want faster results, a second bin lets you fill one while the first one finishes.

Maintaining your pallet bin over time

Check the wood every spring for rot, especially the bottom boards. Pallets last longest if they stay relatively dry — a roof or tarp over the top helps, though it slows decomposition slightly. If the bottom boards start to soften or crumble, you can replace just those boards without rebuilding the whole bin.

The wire mesh will eventually rust if it is steel, but quarter-inch hardware cloth usually lasts as long as the wood does. If rust becomes a problem after several years, you can replace the mesh by removing the old staples and stapling new mesh in place.

Most people rebuild their pallet bin every three to five years. Because pallets are free or cheap, this is not expensive. Some people keep the same frame and just replace the rotted boards, which is faster than starting over.

Frequently Asked Questions

Can I use pallets that have been treated with chemicals?

No. Pallets stamped "MB" were treated with methyl bromide and should not be used for compost. Pallets stamped "HT" were heat-treated and are safe. If there is no stamp or you cannot read it, ask the person giving you the pallet what it was used for. Pallets from food suppliers are almost always safe.

Do I need a lid on the bin?

A lid is not required, but it helps keep rain out and speeds decomposition by trapping heat. You can make a straightforward lid from scrap plywood or buy a metal grate. Many people just leave the bin open and turn the pile occasionally.

How do I know when the compost is finished?

Finished compost looks like dark brown soil, smells earthy, and crumbles in your hand. You should not see recognizable food scraps or leaves. This usually takes six months to a year depending on what you add and how often you turn it.

Can I put diseased plants in the bin?

No. Diseases and pests can survive the composting process and spread to your garden. Throw diseased plants in the trash or burn them if your local rules allow it.

What if my bin attracts rats or mice?

Make sure the wire mesh is securely stapled and covers the entire bottom and lower sides. Do not add meat, dairy, or oily foods, which attract rodents. If you already have rats, you may need to move the bin farther from your house or use a plastic bin with a tight-fitting lid instead.