A brief history of stone walling

[edit] Introduction

A stone wall is any wall comprised of stones, be that natural stone, cut stone, or reconstituted stone, with or without lime or cement mortar. It can be a solid wall constructed in layers with just the inner face, the outer face or main body of the wall made of stone and with or without a cavity. Stone wall cladding refers to a wall where only the outer facing material is a thick layer of stone.

[edit] Early stone walls

Solid stone walls are some of the earliest forms of construction, particularly drystone walling which would have been built during the Neolithic period in the UK. These walls would have been made up of two layers of stone, facing each side and packed with smaller infill stones without any binder or mortar. Scottish blackhouses are one example, which date from around 3000 BCE, built with dry stone solid walls over half a metre thick, and a timber turf roof. They were built to house crofters and their livestock during harsh weather.

The Egyptians built solid stone walls mainly from limestone and sandstone, cut into large blocks and sometimes carved. There is some evidence that lime was used by the Egyptians, but prepared and used as a plaster.

It was the Romans who moved from creating dry stone (or Cyclopean) walls, to sun dried brick walls, often built on a base or socle of massive stones. Through the development of a mortared rubble construction called opus caementicium the Romans moved towards solid stone walls held together with Roman concrete construction, these were quicker to build. By around 150 BCE the Romans commonly used lime as mortars to build solid stone walls made up of two layers built concurrently for speed, firstly an inner core of small stones in mortar (caementa) and then a facing layer of stone or brick. Different names were given to the different facing finishes; Opus incertum a small block random pattern, Opus reticulatum a rectilinear horizontal pattern of stones, Opus testaceum a brick faced concrete and Opus mixtum rectilinear strips of stones and bricks.

A significant number of Roman remains from forts to amphitheatres, gateways and temples can still be found around the UK, many of which highlight their use of solid stone construction, whilst some near complete buildings can also be found. The lighthouse at Dover Castle, of the old Roman port of Dubris is one of only 3 remaining and still standing Roman lighthouses in the world, made of solid stone with mortar, as well as largest surviving gateway of Roman Britain at Colchester. It is worth noting that although many Roman walls may have been constructed as solid layered finished walls, in his monumental set of books, De architectura (On Architecture) Marcus Vitruvius Pollio, wrote possibly the first handbook for Roman architects and indeed possibly the first mention of the benefits of adding a cavity for stone walls.

“…if a wall is in a state of dampness all over, construct a second thin wall a little way from it…at a distance suited to the circumstances…with vents to the open air…when the wall is brought up to the top, leave air holes there. For if the moisture has no means of getting out by vents at the bottom and at the top, it will not fail to spread all over the new wall.”

Marcus Vitruvius Pollio, De Architectura; The Ten Books on Architecture, Book VII, Chapter IV, On Stucco Work in DampPlaces; Translated by Morris Hicky Morgan, Harvard University, Harvard University Press, 1914. Vitruvius wrote in the time of Augustus (63 BC – 14 AD) and it is believed that he wrote this around 15 BC.

“this we may learn from several monuments…in the course of time, the mortar has lost its strength…and so the monuments are tumbling down and going to pieces, with their joints loosened by the settling of the material that bound them together… He who wishes to avoid such a disaster should leave a cavity behind the facings, and on the inside build walls two feet thick, made of red dimension stone or burnt brick or lava in courses, and then bind them to the fronts by means of iron clamps and lead.”

Marcus Vitruvius Pollio, De Architectura; The Ten Books on Architecture, Book II, Chapter VII, Methods of Building Walls, 15 BC.

[edit] Medieval stone walls

After the fall of the Roman Empire around 500 CE and into the Middle Ages, solid stone wall construction continued as a prevalent building material throughout Britain. Medieval builders had a good understanding of engineering and of stone wall construction, often building large temporary timber structures to keep stone walls in place as the lime mortars set, creating increasingly sophisticated architecture. A large number of churches built prior to the battle of Hastings in 1066, many of which stand today, are some of the oldest buildings in England, mostly solid wall construction with lime mortar. The oldest is likely to be beehive cells a monastic centre Eileach an Naoimh, Argyll, Scotland or St Martin's Church, Canterbury which is the oldest church building in England, and is still being used.

During and after the Norman conquest, William the Conqueror ordered the construction of a vast number of castles, towers, cathedrals and churches across his realm, almost all of which were solid stone wall and most made from Caen stone brought from France. The best known examples of these are Norwich, Lincoln and Richmond Castles, Canterbury Cathedral, Westminster Abbey and the Tower of London. In general the stone in most Medieval castle walls was built within a wooden frame designed to hold it in place while the mortar dried, in some cases for thicker walls, a cavity may have been introduced though it would usually have then been completely filled with rubble. In some examples very wide cavities were created between two single stones walls to house a thin stair case or rampart.

[edit] Tudor, Stuart, Georgian, Victorian and Edwardian walls

In terms of stone, rubble and flint constructions these generally remained solid throughout this period, although two layers of construction was relatively common, such as stone rubble externally and brick internally. The cavity between was normally filled with a rubble and lime mix and the occasional bonding stones joining both layers.

It was not until some time into the Victorian period that stone walls with two wythes (or vertical layers) and a gap as found in cavity wall construction started to appear. Whilst the book An encyclopaedia of architecture: historical, theoretical, and practical, written by Joseph Gwilt was first published in 1842, indication seems to be that it only included an illustration of a cavity wall in the later edition of 1899, describing different brick ties.

It is likely that the brick tax which was only repealed in 1850 would have impacted any earlier developments, particularly as in its later years maximum brick sizes were stipulated to control tax avoidance through the manufacture of larger bricks. There is some evidence to suggest that a few early Victorian buildings used longer stones to tie across the two wythes of early cavity walls, though bespoke tiles, bricks, wrought and cast iron ties developed as early as 1890. The book on Building Construction by Professor Henry Adams published in 1906 illustrates a number alternatives to the early glazed brick tiles which included metal ties more akin to modern cavity ties.

[edit] Related articles on Designing Buildings

• Accredited construction details ACDs.
• Building damp-free cavity walls.
• Building with structural stone.
• Choosing stone.
• Coade stone.
• Defects in stonework.
• Dry stone walling.
• Finding stone to conserve historic buildings.
• Masonry.
• Modern Stonemasonry.
• Natural stone cladding.
• Natural stone.
• Repairing historic buildings.
• Sustainable stone.
• Sourcing stone to repair Exeter Cathedral.
• Stone dressing.
• The cavity wall real performance question.
• Two New Ludgate Portland Stone Feature Wall
• Types of stone.
• Use of Stone in Monks Lantern Weybridge.
• Vapour barrier.
• Wall types.

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