Know your enemy before you spend a penny

Foxes, badgers and rats each break into a run in a different way, and understanding that is what stops you wasting money on the wrong materials. A fox will dig, and it will dig fast, often right at the base of the wire where the soil is soft. It can also climb and squeeze through surprisingly small gaps. Badgers are the brute-force merchants: they don't dig as much as simply lean, push and tear, and a flimsy frame will give way before the wire does. Rats are the quiet ones — they tunnel under, gnaw at anything plastic, and squeeze through a hole the size of a two-pound coin.

Your job is to make every one of those approaches too much effort. None of it requires a professional installer. It requires decent posts, proper mesh and a little patience with a spade.

Buy the right mesh, not the cheap mesh

Chicken wire is for keeping chickens in. It is not for keeping predators out. A fox will chew through it, a badger will rip it off the staples, and a rat treats it as a mild inconvenience. Spend your money here instead.

• Weld mesh, 16 gauge, 25mm x 25mm holes is the standard for a reason. It's rigid enough to hold its shape, small enough that rats can't slip through, and strong enough that a fox gives up.
• Buy a 30m roll of 900mm mesh and a matching roll of 600mm for the skirt. Two rolls usually cover a modest 3m x 2m run with a little spare.
• Galvanised staples, 40mm, hammered in every 100mm along every edge. Not every 300mm. A predator will find the loose bit.
• Avoid plastic-coated garden mesh unless it's welded underneath. The coating hides thin wire.

If your budget is tight, mesh is the one place to spend. Skimp on timber, not on wire.

Posts and frame: sturdy without the invoice

Use 75mm x 75mm tanalised timber for the corner posts and any span over 2m. Anything thinner flexes when a badger leans on it. Set posts 600mm into the ground and backfill with rammed hardcore and a dry-ish concrete mix — a full wet mix is fine in winter, but in dry weather it shrinks away from the post.

For the horizontal rails, 50mm x 50mm tanalised is plenty. Fix with galvanised screws or coach bolts at the corners, not nails, which work loose as the timber moves. A simple post-and-rail frame with a mesh skin stapled over the outside is stronger than a panel system, because the whole thing acts as one unit.

If you have an old shed, a brick wall or a fence line, use it. Two sides of an existing solid structure cut your timber bill roughly in half, and solid walls deter foxes far better than mesh alone.

Buried skirts and slab aprons

This is the part most people skip, and it's the part that matters most. A fox will start digging within a few inches of the wire, so the defence must extend outwards at ground level.

• Dig a trench 300mm deep around the entire perimeter and bury the bottom 300mm of mesh vertically.
• Then bend the mesh outwards into a 450mm horizontal skirt, laid flat just under the turf. Foxes dig at the base of the wire, hit the flat skirt, and lose interest.
• Peg the skirt down with galvanised ground pegs every 600mm, or weigh it with bricks before backfilling.
• Paving slabs laid tight around the outside edge are an excellent belt-and-braces addition, and they also stop rats tunnelling in. Recycled slabs are often free if you ask around.

Rats tunnel deeper than foxes, so if you have a rat problem in the area, a 300mm skirt plus slabs is worth the extra afternoon.

Roof, door and the weak points nobody thinks about

Foxes climb. So do badgers, given something to grip. An open-topped run is an invitation. Cover the whole thing with either heavy-duty weld mesh over a timber frame or corrugated clear PVC sheets on a slight fall. Sheets keep the run dry, which is a bonus in a British winter, but they do need support rails every 600mm.

The door is where most home-built runs fail. Fit a sliding bolt top and bottom, plus a simple barrel bolt with a spring so a curious fox can't nose it open. Add a paving slab threshold under the door so nothing can dig in beneath it. Check that the mesh wraps around the door frame, not just sits against it.

Finally, walk the run once a month looking for gaps, loose staples and soft ground where something has been scratching. Ten minutes of inspection beats an hour of rebuilding.

Cheap wins and second-hand sourcing

You can build a solid 3m x 2m predator-proof run for well under the cost of a fitted one if you source timber from online marketplaces, local reuse groups and skips. Pallets are excellent for cladding and frames once dismantled — just check for protruding nails. Old scaffold boards make superb, long-lasting base rails. Galvanised mesh occasionally turns up second-hand, but inspect it for rust and kinks before you part with cash.

Keep feed in galvanised bins with clip lids, clear spilled grain nightly, and keep grass and rubbish away from the wire. A tidy run is a predator-resistant run, and your hens will thank you for it with eggs right through the winter.