Basic repairs to a dry stone wall can be carried out yourself, says Which? Local-recommended Alan Devonport. Find out how to fix gaps or running joints and when to call a professional.
Dry stone walls: repair and maintenance
Boundary or retaining dry stone wall?
Repairs to a simple boundary (freestanding wall) can be carried out yourself. Retaining walls (those beside a bank), on the other hand, should be repaired by a specialist contractor.
Dry stone wall problems
'Gaps' – where a section of the wall has moved significantly or started to collapse – are a common problem. Tackle these by dismantling a V-shaped section of the wall around the problematic area and rebuild.
'Running joints' – where a roughly straight line, running vertically, appears between stones - reduce the stability of the wall. Though less urgent than gaps, a running joint can be fixed in the same ways as a gap: by dismantling a V-shaped section and rebuilding.
In cases where a tree is damaging a wall, contact a professional waller who will 'bridge' the roots allowing for more growth.
How to rebuild a section of a drystone wall
Drystone walling tools
Specialist 'Pennine walling hammers' – a tool with a square end for finishing the sides of stones – cost about £20 from an agricultural supplier.
A mattock and a shovel will also be useful.
1. Match the design and type of stone
By looking at a cross-section of the partly-dismantled wall, you’ll be able to repair the wall according to the existing design. Always match the type of stone too, in keeping with local style.
In Derbyshire, for example, dry stone walls tend to made from carboniferous limestone whereas in Doncaster, they are usually magnesium limestone.
2. Build with a 1:6 'batter'
Boundary walls are constructed with two sides or 'skins', tapering inward to the top at a 1:6 gradient. Maintain this inward gradient (known as the 'batter') as it helps with stability and encourages rain to roll off.
3. The 'first lift'
Start with the largest stones to build the 'first lift'. As you work upward, the stones should get smaller. Place the stones according to the dry stone waller's 'strength in length' maxim – with their longer side pointing into the wall.
You should also build as you would a brick wall with the stones level and the joins bridged by the stone above and below. As Alan says: 'One on two, two on one!'
4. Fill with 'hearting' stones
Put 'hearting' or 'fill' stones into the space between the two skins. Never use soil or mortar and place each fill stone solidly rather than pouring them in haphazardly.
5. 'Through' stones and further lifts
Use a larger 'through' stone, which spans the entire width of the wall at 1m intervals vertically.
The second and any subsequent 'lifts' should take the same form as the first, except that they’ll be tapering in using smaller stones toward the top.
6. 'Coping' stones
Finish the wall with 'coping' tones – these sit vertically and join the two skins. Often, they’ve a curved shape.
Hiring a dry stone walling professional
How much does it cost?
Dry stone walling contractors will usually give you a quote according to the size, in square metres, of the wall being constructed or the area being repaired.
Factors which will add to the cost include purchase and delivery of stones and access to the site. Stone costs between £30-£100 per tonne, depending on type and your location.
How long will it last?
Provided the wall is properly built, you can expect it to last a lifetime.
About our expert trader
Our expert: Alan Devonport
Alan Devonport is a dry stone walling contractor based in Barnsley, South Yorkshire.
Which? Local members have praised Alan and his team for their expert craftsmanship and helpful advice.
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