Why build dry stone on a small holding

A dry stone wall is more than a boundary. On a small holding it is a windbreak for the vegetable plot, a scrap of shelter for lambs on a wet April morning, and a home for slow-worms, field mice and solitary bees. Built well, it will still be standing when the fence posts around it have rotted twice over.

It is also the most forgiving kind of walling there is. There is no mortar to mix and no curing to fret about, and if a section goes wrong you simply lift the stones out and start again. But it is not a random pile of rock. It is a piece of engineering with rules behind it that are centuries old and worth learning before you lift the first stone.

Choose local stone and learn to sort it

Use the stone that already grows in your parish. Local limestone, sandstone or slate matches the walls around it, weathers in sympathy with the landscape and, crucially, comes in the flat, workable shapes a wall needs. Ask a neighbouring farmer with a collapsed wall, or a small quarry, and be honest about how much you need: a metre of wall 1.2 metres high swallows roughly a tonne of stone.

Before you build anything, sort. Tip the pile out and make four heaps:

• Footings: the biggest, flattest, heaviest stones. These go below ground and take the whole weight of the wall.
• Face stones: roughly rectangular stones with two flat sides and a straight edge. These are your building blocks and deserve the most care.
• Hearting: every small, wedge-shaped, awkward lump. Never throw these away — they are what holds the wall together.
• Throughs and copes: long stones that span the full width of the wall, and a good set of top stones. Set these aside early, or you will find you have used them halfway up.

Set the line, dig the footing, keep the batter

Run a string line tight along the line of the wall and dig a shallow trench, about 150 to 200 mm deep and wider than the base. Do not concrete it. A dry stone wall wants to sit on firm, well-drained ground, not on a rigid strip that will crack the moment the soil moves.

A wall's base is roughly half its height: for a 1.2 metre wall, aim for around 600 mm wide. Then taper it as you rise. That inward lean is called the batter, and it is what gives a dry stone wall its strength — the whole thing is a shallow triangle, leaning into its own weight. Aim for about 1 in 6, which in practice is a hand's width of lean over three or four courses. Use a straight edge and a spirit level as you go, and check your batter on both faces rather than trusting your eye.

Build in courses, with hearting and through stones

Build both faces at once, keeping them level with each other. Lay each stone on its natural bed — the flat face it was formed with — with its longest side running into the wall, never along it. Every stone should sit solidly on the one below, with no rocking. Break your joints as a bricklayer would: one stone over two, two over one, so no vertical joint runs straight up the wall.

As you rise, fill the middle with hearting, packed tight with your fingers and the peen of your hammer. This is the part beginners rush and it is the part that matters most. Hearting transfers weight from the face stones into the core, so the wall behaves as one mass rather than two thin skins. Never tip hearting in from the top; place it as you go, course by course.

Every metre or so along the wall, and roughly every 600 mm of height, lay a through stone. These long stones run right across the width of the wall, tying the two faces together. Stagger them, so the wall does not develop a line of weakness, and set them slightly proud of the face if you like the look of it.

Tools, pace and wildlife

You need less than you think:

• A walling hammer, around 2 kg, with a square face and a chisel peen for dressing stone.
• Sturdy leather gloves and safety glasses — stone splinters are vicious.
• A string line, pins and a straight edge or level.
• A spade and mattock for the footing, a bucket for hearting, and a kneeling pad.

Be realistic about pace. A beginner will manage a metre or two of finished wall in a weekend. Two metres of good wall a day is a fine target, and a wall built slowly will outlast one built fast. Work with your legs, not your back, and never lift anything you would not carry across a yard.

Do check what is living in the wall before you take it down. Nesting birds are protected from March to August, and the hearting of an old wall is a favourite winter refuge for newts, slow-worms and hedgehogs. Dismantle in short sections over several weeks, leaving the rest of the wall intact as cover, and rebuild each stretch before moving on.

Coping, settling and honest repairs

Finish with cope stones set on edge, upright and tightly packed, leaning very slightly back into the wall so rain runs off. Some wallers use a rounded comb top, others a neat row of verticals known locally as cock and hen. Whichever you choose, the coping is what sheds water down the faces and away from the hearting.

Expect the wall to settle through its first winter. A few copes may shift; press them back. If a bulge appears, the hearting has failed and no amount of pushing will fix it — take that section down to sound stone and rebuild it properly. And please, resist the temptation to point a dry stone wall with cement. It traps water, cracks in frost and turns a repairable wall into one that has to be rebuilt.

Build it well, one stone at a time, and the wall will do the rest: quietly, for a very long time.