Know your enemy before you buy a single staple

If you keep hens, you keep foxes — it is simply a question of when one finds you. A hungry dog fox will test every inch of a run, and it will do it at three in the morning, in daylight while you are at work, and again the moment you get complacent. Badgers are a different problem altogether. They are enormously strong, they dig like miniature excavators, and because they are protected you cannot deal with them by any means other than good fencing. If badgers are taking your birds or emptying your feeders, the answer is engineering, not confrontation.

The good news is that a genuinely predator-proof run does not require ready-made panels at forty or fifty pounds a metre. It requires the right mesh, a sensible frame, and one or two details most people skip.

Mesh is the one place you should not scrimp

Walk into any farm shop and you will find rolls of hexagonal chicken wire at a tempting price. Do not be tempted. A fox will bite through light poultry netting and push straight through the gap it has made. It is fine for keeping hens in a corner of the garden, but it is not a barrier.

• Use welded mesh with 25mm x 25mm holes, and look for wire of at least 1.2mm — often sold as 16 gauge. Heavier is better still.
• Buy it in rolls rather than cut panels. A 10-metre roll of 1.8m-high weldmesh is far cheaper per metre than anything pre-framed.
• For the walls, 1.8m height is ideal. It keeps the run comfortable to walk into and makes it much harder work for anything trying to get over the top.
• Where two pieces of mesh meet, overlap them by at least 50mm and sandwich the join between a timber batten and the frame, then staple through both layers.
• Use galvanised staples, not ordinary ones, and knock them in at an angle so they cross the wire rather than running alongside it.

Build the frame from what you can scrounge

Tanalised 75mm x 50mm timber is the workhorse here. Posts want to be around 2.4m long, with 600mm sunk into the ground — concrete them in if you can, or ram them solid with hardcore and soil. Space posts at roughly 1.5m to 2m centres. Anything wider and the mesh will flex and eventually sag.

Put a diagonal brace across every corner and screw rather than nail where you can; screws hold far better when a fox throws itself at the wire. Reclaimed scaffold boards, pallet timber and offcuts from a local reclaim yard will do the job for bracing and for the bottom rail. Skip anything chipboard or MDF-based, which turns to mush after a wet winter.

The buried skirt is the cheapest upgrade you will ever make

Most people fix mesh to the outside of the frame and stop at ground level. That is exactly where a fox starts digging. Instead, let the mesh continue past the bottom of the frame and outwards, flat along the ground, in an L shape.

• Run the skirt out 450mm to 600mm from the base of the run.
• Peg it down with galvanised ground pegs every 500mm or so, and weight the outer edge with a few bricks while it settles.
• Fold the outer edge back on itself by 100mm so no sharp ends stand up to catch a paw or a boot.
• Alternatively, dig a 300mm trench and bury the mesh vertically, turning it outwards at the bottom. Neater, but twice the work.

A row of paving slabs laid tight along the perimeter does the same job and has two bonuses: you can mow right up to it, and no weeds grow into the wire. Slabs are frequently free on local listings if you are willing to collect.

Latches, roofs and the details that catch people out

A fox is quite capable of nosing open a simple hook-and-eye, and a badger will simply shove a gate until something gives. Use two fastenings per gate — a bolt at the top and another at the bottom — or a carabiner through a hasp. Anything a child could open, a fox can open.

Do not forget the top. Foxes climb well and will happily drop into an open-topped run. A mesh roof, or a solid corrugated roof over part of it, solves the problem and gives the hens somewhere dry to shelter. Check that no gap anywhere exceeds 25mm, particularly where the roof meets the wall and around gate frames, which tend to twist and open up over time.

An automatic pop-hole door is the single best quality-of-life purchase for a smallholder who is out at work. Even the budget ones cost less than a replacement flock, and they close reliably at dusk when foxes are most active. Keep feed in a metal bin with a clipped lid, and clear up spills, because spilt layers pellets pull in rats, and rats pull in everything else.

What it actually costs

• A 10m roll of 1.8m weldmesh in 25mm squares: roughly £60 to £100.
• Tanalised posts, eight to ten of them: £8 to £12 each.
• Galvanised staples, brackets, screws and ground pegs: £20 to £30.
• Second-hand paving slabs or a mesh skirt: often nothing but a bit of sweat.

For a run of around 6m by 3m, you should be looking at £150 to £250 all in — a fraction of what pre-built panels cost, and considerably stronger. Spend your money on mesh and latches, scrounge your timber, and bury a skirt. Do those three things properly and you will sleep soundly while the fox paces the perimeter and gets nowhere.