Traditional stone buildings

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When I travel around Britain it is the stone buildings that for me best articulate the landscape. Their walls convey something about the geology beneath the ground and instantly conjure the mood of a place. Stone provides the rich honey tones of the Cotswolds, the brooding, rugged beauty of northern towns, the solidity of Cornish fishing villages and the flinty glint of East Anglia.

It was the Normans who first made stone popular. When they conquered Britain in 1066 they built castles, monasteries and royal houses with stone and it became a high status material much desired by noblemen for their halls. Unlike the wooden homes of the time, stone has the obvious advantages of being durable and less of a fire risk; it can also be carved to create high levels of ornamentation.

With time, stone was used to build all types of houses but the kind of stone, the way it was laid and the quality of work was still directly related to status. For the grandest buildings stone was imported from France or transported across country from English quarries recognised for the exceptional quality of their product. More normally, stone was hewn nearby. Many towns and villages had their own quarries and the stone is often known by the quarry it originally came from; grey Barnack stone comes from Northamptonshire and honey-toned Chilmark is from Wiltshire, for example.

Limestone, sandstone and granite are the three chief building stones used in Britain. Even so, there are huge variations in their individual characteristics depending on which geological stratum they come from.

Limestone is relatively easy to work so it is commonly carved and made into moulded mullions. With sandstone, there is likely to be less decoration since the stone can be either hard or soft, so may lose some of the detail because it tends to crumble and weathers easily, or is much too difficult to work with. Granite is the hardest of all the common building stones.

Traditional quarrying
Philpots Quarry at West Hoathly, in West Sussex, has been in business for more than 150 years and the stone is the same type of sedimentary sandstone used to build notable buildings like Battle Abbey and Rudyard Kipling’s home, Bateman’s. The quarry is now operated by the family firm Lambs, and Paul South, their stone specialist, explained to me that the stone lies beneath up to seven metres of clay. As I stood in the depths of the quarry’s lunar-like landscape I could see this clearly; I was time travelling back millions of years looking at strata unseen since cretaceous times.

In many quarries stone has to be drilled and split to free it but here it is relatively easy to extract because it is lined by ancient natural fissures. Some of the biggest blocks weigh up to 20 tonnes. The stone is graded according to its consistency and quality. Large blocks are cut on a reciprocating saw, which uses a push/pull cutting action. Smaller blocks are cut on Lambs’ 2.2 metre diameter primary saw and end up looking like sliced bread – each slice is called a ‘scant’.

Paul told me that the Philpots Quarry’s top grade stone is predominantly a honey and oatmeal shade with fine striations that is suitable for carved work and finished building masonry. Lesser building grade stone is also suitable for masonry work but contains a greater content of striations and is therefore not appropriate for fine carved work.

Some scants are taken to the cropping line where they are ‘cropped’ (guillotined) and then sawn to form regularly shaped blocks. With a hammer and chisel the ‘arrises’ (edges) are then knocked off to remove the saw marks and create what is known as split face walling. Better quality scants go to a secondary saw where all six edges are sawn to form ashlar blocks or blocks for masonry carving and fine detailing.

Everything from intricately carved window lintels to statuary is produced at Lambs. The masons first make plastic templates from detailed drawings of the finished product. These templates are laid on to the stone and traced around with a diamond scriber to transfer the pattern. Nowadays the masons use angle grinders and the latest air powered chisels to carve the stone. Even so, the job requires incredible dexterity and craftsmanship.

Making repairs
We tend to think of stone as a hard, unforgiving material yet this impression of durability is frequently incorrect. Some of the finest stone buildings have deteriorated appallingly through neglect, and because of poorly specified materials and incorrect methods of repair and cleaning, so it is well worth obtaining advice and employing a craftsman with skill, aesthetic understanding and expert knowledge of stone.

Traditionally lime mortar was used to build walls so avoid using cement-based products. Lime allows the building to ‘breathe’ and move, so it is important, with any new work, not only to match the colour and style of the original pointing but also its composition and strength.

Every type of stone weathers in a different way and the rate of erosion can be hastened by air pollution, exposed locations, repointing with cement mortars or, for example, if water has been allowed to run down its face from a leaking gutter or downpipe. Where erosion has occurred it is not always necessary to repair the stone as long as the cause of the problem has been addressed.

If stone needs to be replaced it should be carved and dressed to match the original. More importantly, the new pieces must be geologically similar as chemical reactions can sometimes occur between stones of different types.

Cleaning stone
One of the most complex and controversial areas involving stonework is cleaning. Within a few minutes you can remove the attractive patina of age, which has taken years to evolve, and, at the same time, cause irreversible damage. Balancing this is the fact that dirt or paint can not only spoil the appearance of stone but sometimes cause erosion.

Whenever cleaning is to be undertaken, the gentlest method should always be considered first, tests must be carried out and, if there is any doubt, the process should be stopped and expert advice sought. Bear in mind that limestone and sandstone are chemically dissimilar and require different cleaning methods.

Word for word: A stone glossary

• ASHLAR WORK Has very fine joints and can only be achieved with fine-grained stone, which is capable of being dressed to a smooth finish.
• COURSED RUBBLE WORK Is composed of roughly dressed stone, levelled out to similar thickness and laid in courses.
• DRESSED STONE Is squared all round and smooth on its face.
• RANDOM RUBBLE WORK Is composed of stone taken directly from the ground and laid in a wall in random sizes.
• TOOLING A pattern of cuts in the face of a stone.

Visit Roger Hunt's website at huntwriter.com

WORDS ROGER HUNT PHOTOGRAPHS ©NTPL/JOHN MILLER, ROGER HUNT
Featured in the March 2010 issue of Period Living

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