Stonemasonry

Stonemasonry

What is Stone Masonry

The craft of stonemasonry (or stonecraft) has existed since the dawn of civilization – creating buildings, structures, and sculpture using stone from the earth. These materials have been used to construct many of the long-lasting, ancient monuments, artifacts, cathedrals, and cities in a wide variety of cultures. Famous works of stonemasonry include the Taj Mahal, Cusco’s Incan Wall, Easter Island’s statues, the Egyptian Pyramids, Angkor Wat, Borobudur, Tihuanaco, Tenochtitlan, Persepolis, the Parthenon, Stonehenge, and Chartres Cathedral.

The Craft

  • Is the craft of shaping rough pieces of rock into accurate geometrical shapes, mostly simple, but some of considerable complexity, and then arranging the resulting stones, often together with mortar, to form structures.
  • Quarrymen split veins, or sheets of rock, and extract the resulting blocks of stone from the ground.
  • Sawyers cut these rough blocks into cubes, to required size with diamond-tipped saws.
  • Banker masons are workshop based, and specialize in carving stones into intricate geometrical shapes required by a building’s design. They can produce anything from stones with simple chamfers to tracery windows, detailed mouldings and the more classical architectural building masonry. When working a stone from a sawn block, the mason ensures that the stone is bedded in the right way, so the finished work sits in the building in the same orientation as it was formed on the ground. The basic tools, methods and skills of the banker mason have existed as a trade for thousands of years.
  • Carvers cross the line from craft to art, and use their artistic ability to carve stone into foliage, figures, animals or abstract designs.
  • Fixer masons specialize in the fixing of stones onto buildings, using lifting tackle, and traditional lime mortars and grouts. Sometimes modern cements, mastics and epoxy resins are used, usually on specialist applications such as stone cladding. Metal fixings, from simple dowels and cramps to specialised single application fixings, are also used. The precise tolerances necessary make this a highly skilled job.
  • Memorial masons or monumental masons carve gravestones and inscriptions.
  • The modern stonemason undergoes comprehensive training, both in the classroom and in the working environment. Hands-on skill is complemented by intimate knowledge of each stone type, its application and best uses, and how to work and fix each stone in place. The mason may be skilled and competent to carry out one or all of the various branches of stonemasonry. In some areas the trend is towards specialization, in other areas towards adaptability.

Types of stone

  • Typical Aberdeen city street showing the widespread use of local granite
  • Stonemasons use all types of natural stone: igneous, metamorphic and sedimentary; while some also use artificial stone as well.
  • Igneous stones: Granite is one of the hardest stones, and requires such different techniques to sedimentary stones that it is virtually a separate trade. With great persistence, simple mouldings can and have been carved into granite, for example in many Cornish churches and the city of Aberdeen. Generally, however, it is used for purposes that require its strength and durability, such as kerbstones, countertops, flooring, and breakwaters.
  • Igneous stone ranges from very soft rocks such as pumice and scoria to somewhat harder rocks such as tuff and hard rocks such as granite and basalt.
  • Metamorphic: Marble is a fine stone easily workable, that comes in various colours, mainly white. It has traditionally been used for carving statues, and for facing many Byzantine and Renaissance Italian buildings. The first and most admirable marble carvers and sculptors were the Greeks, namely Antenor (6th c. BC), Phidias and Critias (5th c. BC), Praxiteles (4th c. BC) and others who used mainly the marble of Paros and Thassos islands, the whitest and brightest of all, although not the finest, and also the Pentelikon marble. Their work was preceded by older sculptors from Mesopotamia and Egypt, but the Greeks were unmatched in plasticity and realistic (re)presentation, either of Gods (Apollo, Aphrodite, Hermes, Zeus, etc.), or humans (Pythagoras, Socrates, Plato, Phryne, etc.). The famous Acropolis of Athens is said to be constructed using the Pentelicon marble. The traditional home of the marble industry is the area around Carrara in Italy, from where a bright and fine, whitish marble is extracted in vast quantities.
  • Slate is a popular choice of stone for memorials and inscriptions, as its fine grain and hardness means it leaves details very sharp. Meanwhile, its tendency to split into thin plates has made it a popular roofing material.
  • Sedimentary: Many of the world’s most famous buildings have been built of sedimentary stone, from Durham Cathedral to St Peter’s in Rome. There are two main types of sedimentary stone used in masonry work, limestones and sandstones. Examples of limestones include Bath and Portland stone. Yorkstone and Sydney sandstone are well-known sandstones.

Types of stonemasonry

  • Rubble Masonry: When roughly dressed stones are laid in a mortar the result is a stone rubble masonry.
  • Ashlar Masonry: Stone masonry using dressed (cut) stones is known as ashlar masonry, whereas masonry using irregularly shaped stones is known as rubble masonry.
  • Stone Veneer: Stone veneer is used as a protective and decorative covering for interior or exterior walls and surfaces. The veneer is typically 1 inch (2.54 cm) thick and must weigh less than 15 lb per square foot (73 kg m−2) so that no additional structural supports are required. The structural wall is put up first, and thin, flat stones are mortared onto the face of the wall. Metal tabs in the structural wall are mortared between the stones to tie everything together, to prevent the stonework from separating from the wall.
  • Slipform Stonemasonry: Slipform stonemasonry is a method for making stone walls with the aid of formwork to contain the rocks and mortar while keeping the walls straight. Short forms, up to two feet tall, are placed on both sides of the wall to serve as a guide for the stone work. Stones are placed inside the forms with the good faces against the form work. Concrete is poured behind the rocks. Rebar is added for strength, to make a wall that is approximately half reinforced concrete and half stonework. The wall can be faced with stone on one side or both sides.

Training

Traditionally medieval stonemasons served a seven-year apprenticeship. A similar system still operates today.

A modern apprenticeship lasts four years. This combines on-site learning through personal experience, the experience of the tradesmen and college work where apprentices are given an overall experience of the building, hewing and theory work involved in masonry. In some areas colleges offer courses which teach not only the manual skills but also related fields such as drafting and blueprint reading or construction conservationism. Electronic Stonemasonry training resources enhance traditional delivery techniques. Hands-on workshops are a good way to learn about stonemasonry also. Those wishing to become stonemasons should have little problem working at heights, possess reasonable hand-eye co-ordination, be moderately physically fit, and have basic mathematical ability. Most of these things can be developed while learning.