How to Build a Compost Bin (UK): The Classic Pallet Bin, Step by Step

A compost bin does not have to be bought, and it does not have to be pretty. The single most useful heap on most smallholdings is a rough cube of four reclaimed pallets, wired or screwed together in an afternoon, standing on bare earth in a shady corner. It costs next to nothing, it is big enough to actually warm up and rot properly, and when you want more capacity you just bolt another bay onto the side.

This page is about the build: how to make the bin. The science of what goes in it, the balance of green and brown material, and how to keep a heap sweet and working all live on our companion guide, how to compost. Read the two together and you will have both the container and the recipe. If you are in a pallet-building mood, the same free-materials, few-screws approach also gives you a cheap raised bed.

Why a pallet bin is the smart first build

There is a reason the pallet bin is a homesteading cliche: it works. Pallets are the right size, they are sturdy, the gaps between the slats let air into the heap, and they are usually free. A good compost bin, in the RHS's words, needs to "exclude rain, retain some warmth, allow drainage and let in air", and a slatted pallet cube does three of those four things by design, leaving only a simple cover to sort out the rain.

Size matters more than people expect. The RHS is clear that bins of less than one cubic metre are generally less efficient than larger ones, because a bigger heap holds on to the warmth that the rotting process generates, and a warm heap breaks down faster. That cubic metre is the sweet spot where a heap can start to heat up in the middle rather than just sitting there cold. Here is the happy accident: a standard pallet is roughly 1.2 metres along its long side, so four of them stood on edge box in close to a cubic metre with no measuring at all. The pallet does the sizing for you.

Build a one-bay pallet compost bin

This is the core build and the one most gardens need. Give yourself an afternoon, a cordless drill, some long exterior screws or a coil of galvanised wire, and four decent pallets.

Building a single-bay pallet bin

1. 1

   Pick and level the spot

   Choose a sheltered, part-shade corner on bare soil, somewhere you can reach with a barrow. Clear it and roughly level the ground so the pallets sit square and do not lean. Standing on soil lets worms move up into the heap and lets excess water drain away, which is exactly what you want.

2. 2

   Stand up the back and sides

   Stand three pallets on their long edges to form three sides of a square: a back and two sides. The slatted faces should point inwards. Hold or prop them upright while you fix the first corners.

3. 3

   Fix the corners together

   Join each corner where two pallets meet. The quickest sturdy method is galvanised wire threaded through the boards and twisted tight top and bottom with pliers. For a firmer job, screw a length of batten down the inside of each corner, or drive long exterior screws straight through the overlapping timbers. Aim for at least two fixings per corner, top and bottom.

4. 4

   Sort out the front

   The fourth pallet is your front. The simplest option is to wire it on at one side like a gate so it swings open. For easier access, skip the fourth pallet and instead slot a few loose horizontal boards down between two battens fixed to the front edges, so you can lift boards out as the heap grows and drop them back in. A removable front makes forking the finished compost out far less of a fight.

5. 5

   Firm it up and check it stands square

   Give the whole cube a shove. It should barely move. If a corner racks or leans, add another screw or a diagonal batten across the outside to brace it. A wobbly bin only gets worse once it is full and wet.

6. 6

   Add a lid

   Lay a cover loosely over the top: an offcut of old carpet, a sheet of plywood, a piece of pond liner or weed-suppressant membrane all work. This keeps heavy rain from waterlogging the heap and holds warmth in, while a loose fit still lets air move. Weigh it down with a brick or two against the wind.

Once it is standing, the bin is ready to fill. Start with a layer of coarse, brown material such as chopped woody prunings or scrunched cardboard at the base to help air get underneath, then build up in layers, keeping a rough balance of soft green waste and dry brown waste. The full recipe, and how to fix a heap that has gone slimy or dry, is on our how to compost guide.

Step up to a three-bay system for turning

A single bin is plenty for most households. But if you generate a lot of waste, or you want finished compost on tap, a three-bay system earns its space. The RHS notes that keen composters often prefer several bins in a row, to hold compost at different stages of readiness, and that is exactly what three bays give you.

The idea is a production line. You fill the first bay with fresh material. When it is full, you fork the whole lot over into the middle bay, which mixes in air and kick-starts a faster, warmer rot, and you go back to filling the empty first bay. When the middle bay has rotted down, it moves along to the third bay to finish and mature, ready to spread. So the three bays are, in order: fresh, working, and ready.

Building a three-bay pallet bin

1. 1

   Set out the footprint

   You are making three cubes in a row, so you need a level strip on bare soil roughly 3.5 metres long and a metre deep. Mark it out and clear it before you start fixing anything.

2. 2

   Build the back wall

   Stand three or four pallets end to end along the back line and fix them to each other at every join, so you have one long continuous back. This is the spine that holds the whole thing together.

3. 3

   Add the dividers

   Fix a pallet at each end for the outer walls, then two more pallets as internal dividers, spaced a pallet-width apart, to split the run into three equal bays. Screw or wire each divider firmly to the back wall so it cannot splay outwards when a bay is loaded.

4. 4

   Make removable fronts

   Turning is far easier if the fronts lift out. Screw a batten to each side of every bay opening and slot loose horizontal boards down between them, so you can pull the boards out of one bay, fork the compost across, and drop them back in. Fixed pallet fronts work but make the turning job much harder.

5. 5

   Brace and cover

   Check the whole run stands square and add diagonal battens across any corner that racks. Then cover each bay with its own piece of carpet, board or membrane, as with the single bin, to keep rain off and warmth in.

Other simple compost bin options

Pallets are the classic, but they are not the only way. If you have no pallets, a small garden, or you just want something tidier, here are the common alternatives and how they stack up.

Option	Best for	Rough cost	Watch out for
Pallet bin (1 or 3 bay)	Allotments and gardens with space and plenty of waste	Free to a few pounds for screws	Needs sourcing matching pallets; check the treatment stamp
Wire-mesh cylinder	Cheap, airy heaps and leaf mould in a corner	Low: a roll of galvanised mesh	Dries out fast and holds little warmth, so rots slowly
Repurposed dustbin with holes	Small gardens and tucked-away spots	Free if you have an old bin	Small volume struggles to heat up; drill drainage and air holes
New Zealand box (slatted timber)	A neat, long-lasting bin you want to look good	Higher: bought or cut timber	More time, tools and money than pallets for the same result
Bought 'Dalek' cone bin	Beginners and small households wanting no build	Often subsidised by councils	Usually under a cubic metre, so slower; hard to turn

A wire-mesh cylinder is nothing more than a length of galvanised mesh bent into a circle and clipped shut: quick, airy and ideal for leaf mould, though it dries out and stays cool. A dustbin with holes drilled in the sides and base makes a compact bin for a small plot, but the modest volume never really heats up. A New Zealand box is essentially a smarter pallet bin, built from slatted timber with drop-in front boards, and it looks the part but costs more in time and materials. And the familiar cone-shaped "Dalek" bin, often sold cheaply through local councils, needs no building at all, but most hold well under a cubic metre and are awkward to turn. For a homestead producing real quantities of waste, the pallet bin still wins on capacity for the money.

Getting the siting right

Where you put the bin matters as much as how you build it. The RHS recommends a sheltered spot in partial or full shade, because it keeps the heap from baking dry in summer or freezing solid in winter, and steady conditions are what the composting microbes like. Recycle Now makes the same practical point about access: put it somewhere you can easily add material and get the finished compost out.

Stand the bin on bare soil wherever possible. That earth base, the RHS notes, gives soil organisms and worms access to the heap and lets water drain away freely. If your only option is a hard surface such as concrete or slabs, it will still work, but throw a few spadefuls of garden soil into the base first to introduce the organisms that get things going.

A short "what you need" list

For a single-bay pallet bin, gather:

• Four matching pallets (plus four more if you are building three bays), plain and clean, HT-stamped or unstamped.
• Fixings: a coil of galvanised wire and pliers, or a box of long exterior-grade screws and some offcut batten for the corners.
• A cordless drill with a driver bit, and ideally a wood bit for pilot holes.
• A cover: old carpet, a plywood offcut, a piece of pond liner or weed-suppressant membrane.
• Gloves and sturdy boots, since reclaimed pallets can have splinters and the odd protruding nail.

Most of this you can scavenge or already own. If you need to buy the odd item, a few tagged searches to get you started: galvanised garden wire, exterior wood screws and weed-suppressant membrane.

Common mistakes to avoid

• Building it too small. Under a cubic metre and the heap struggles to warm up, so it rots slowly. Bigger is better, within reason.
• A fixed front. A solid front you cannot open turns emptying the bin into a wrestling match. Make it removable from the start.
• Skipping the cover. In a wet British winter an uncovered heap goes cold and waterlogged. A loose lid pays for itself in speed.
• Sealing it up. The flip side: do not make it airtight. The process needs air, which is why slatted pallets and a loose lid work so well.
• Using dodgy wood. MB-stamped, painted or oily timber has no place near food crops. Check before you build.
• Standing it on concrete without soil. No worms can reach it. If you must use a hard surface, seed the base with a few spadefuls of soil.