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Technical Specifications for Dry Stone Walls

PREAMBLE
hese notes have been prepared to assist professional decision makers; local authority officers, architects, civil engineers, landscape designers, etc in drawing up specifications for dry stone walling work. Before giving the most common measurements, a number of important points should be understood:

  • There are three key areas in the use of dry stone: free standing walls which are by far the most common application of the craft in the United Kingdom; load bearing retaining walls and domestic structures particularly houses, barns and ancient monuments. These notes deal with free standing walls of a generally found type. However, there are distinctive regional variations. All walling work should take into consideration the type, stone and style of other dry stone walls close by.
  • The specifications relating to load bearing walls are far more complex. A leaflet entitled Specifications for Simple Retaining Walls is available from DSWA.
  • Matters appertaining to ancient monuments are too variable to be dealt with in short note form and should be handled by discussion between a dry stone walling consultant and the relevant bodies. In all cases, the Association will endeavour to match the inquirer with the best available specialist.
  • Dry stone walling is as much an art as a science, and this can occasionally give rise to frustration and misunderstanding to those professionals not fully acquainted with it. Seemingly inconsequential considerations can quite substantially affect the ease of construction and hence, price. A site visit and discussion prior to estimating will almost invariably be necessary for the waller.
  • The difference in standards between good and bad work are probably greater than in any other skill. This, combined with the need to recognise the inexperience of those professionals commissioning dry stone walling in judging the quality of the product makes it essential to obtain the services of a qualified waller and with prestigious work, this is particularly so. Again, the Association will help if asked. To emphasise the point: work should last 100-150 years when carried out by a skilled waller, yet failure in 5 or less is frequent.

GUIDELINES

  • Quite apart from statutory requirement, it is good practice to match walls to those in the immediate area both in style and in materials used. There are distinctive local variations – often in relatively small areas.

GUIDELINES cont’d

  • A standard, freestanding wall usually stands 1.4m (4ft 6in) above ground level. Boundary walls (perimeter walls to farms, estates, etc) are more commonly 1.6m (5ft 3in).
Cross-sections of (left) standard “double” dry stone wall and (right) a Galloway March dyke. (Measurements are as a guide only)
  • A wall may be more or less any height, providing this is reflected in the base width.
  • A foundation course is required for all work not built on rock.
  • When restoring walls after ground disturbance (e.g. pipeline works) care should be taken to backfill with subsoil or similar material avoiding organic matter, and to follow this up by mechanical compacting.
  • When dismantling walls with a view to reusing the stone, it is imperative that no soil or other foreign material whatever is mixed with the stone that is to be retained. This usually inhibits the use of machinery. The best course of action is to place a mechanical digger bucket against the wall and hand load. Aim to keep the various components separate (i.e. top stones, through stones, building stones, etc).
  • It is important to bear in mind that the waller can obviously only work with the material supplied. Surprisingly, it is not at all uncommon for the commissioning body to provide a specification similar to the drawings overleaf, yet supply stone that makes faithful execution of that specification impossible. Some stone can be coursed; some is only suitable for random walling. Where an exact reproduction is not essential, allowances must be made according to materials and conditions.

Note: Separate specifications are available from DSWA for a range of regional or distinctive styles of dry stone walling including single walls and simple retaining walls.

FURTHER INFORMATION
The Association endeavours to respond to all requests for specific information regarding dry stone wailing. The DSWA offers a mail order service on books, which includes a number of technical manuals, which would make useful reading, and produces a register of working wallers, which is free of charge. Full details available on request (please include a stamped, self-addressed envelope).

Dry Stone Walling Association
Westmorland County Showground,
Lane Farm, Crooklands,
Milnthorpe, Cumbria, LA7 7NH

tel: 015395 67953
www.dswa.org.uk