LOGGIA Nº12 Northern Arabia the patterns and repetitive devices Earth architecture ENGLISH VERSION applied by tribesmen to their woodwork and to the mud Strong in compression and weak in tension, massive by which coats their buildings has a quality which makes nature and generally heavy, earths and brick are, with them unique in time and place; and in that sense they stone, the characteristic material of walling. Being inert John Warren are as important as the great terracottas displayed on in a practical, if not a chemical sense, they are durable Form, Meaning and Purpose: Italian Renaissance buildings. The culture is and take on special hues and characteristics with age. Ethical and Aesthetic Objectives in commemorated in the artefact, and the qualities of the The methods of assembly – bonding – and forms of the Conservation of Earth Buildings society that created a civilization are measured in the construction have produced a wide variety of historic architecture left behind as much as in their literature or characteristics intrinsic are appropriate to the context Conservation serves several purposes. In the social their music. Societies may disappear but the cultural and produce a result that is acceptable in terms of the context, the fabric of mans built past is meaningful to artefact remains to provide a direct access to those who historic qualities of the place or building. him in same fundamental way as the landscape he created it. If man’s earliest constructions were of mud simply piled inhabits, and people deprived of the environmental asset The very rarity of some fragments of past societies may together and dressed into an homogeneous mass the of their past lack a part of the understanding of their in itself be a special reason for, and give a particular next step was to provide for the use of hardened mud, own history. The sense of loss can be tangible, resulting purpose to, conservation. The city of Bokhara in easier to transport, to be laid in place and joined with a in instability and a yearning for environmental security. Uzbekistan preserves a mausoleum with an wetter mud. So the first mortar was created. Only where The distinctive shapes of the earth villages of sub- extraordinary intricacy of patterned brickwork mud is used in plastic state can a mortar be avoided, so Sahara Africa provide their inhabitants with evidence of attributable to the tenth century King, Ismail the the form of a masonry structure from earliest times has their origins in just the same way as do the mellow Samanid. No other comparable building survives. Were been significantly dependent on the bonding and the brick walls of some great Spanish town whose citizens it not for this one rich example, patterned like a tribal nature of mortar used as well as the character of the sense in the environment the deep roots of their past. rug in solid brickwork, there would be almost no brick whether of mud or of burnt clay. Early bricks No conservator need be ashamed of admitting that one evidence of culture known otherwise only by were of a type known as plano-convex, that is to say fundamental purpose of his work is the retention of a fragmentary remains in poetry and literature. Rather having curved upper surfaces, being hand moulded like fabric which meets the deep psychological needs of more is known earlier Sasanian civilisation in a lump of dough. These have been exposed in the those who inherit it and pass it on. Mesopotamia but of Sasanian building skills the one excavations of the Nile and the Tigris-Euphrates valleys The primary objective in consolidating or strengthening structure that gives measure to their achievement is the in buildings dating back several millenia but these and structures is to improve their stability. Where a visible great parabolic brick vault standing today at Salman many other forms of unbaked earth bricks have been intervention is called for, as is usually yhe case, a series Pak, south of Baghdad. This single remaining structure covered with mud or render as an external coating so of questions is raised. These lie outside the structural of the great palace of Chosroes Anushirvan at Ctisphon that the intrinsic nature of the wall structure will have problem itself. It is these that we now seek to explore. is the single building by which the structure been concealed from the outset. It is the nature of mud Structurally the strength of the building and probably achievement of that world power can now be assessed. brick construction to be rendered over with a mud also its longevity will have been enhanced. The These arguments of purpose are historical and to them plaster and the quality that arises in earth structures, intervention must raise ethical considerations which by must be added one other – science. Any historic fabric therefore, is that of a superficial layer or coating definition relate to the rightness of the action and the is evidence of the circumstances and techniques of its designed to be sacrificial and to be frequently renewed. honesty of its handling. Other practical considerations age of construction. The circumstances of its building, This layer may be of exactly the same material as the then follow. determined by available materials and the use of wall. It may be reinforced, perhaps with straw to give it A building has four functions to perform: structural, techniques inherited or invented, are the prime greater cohesion to reduce the nature and size of the practical, aesthetic and evidential. Ideally every activity evidence of the movement of civilisations and one cracking and so to give it more weathering resistance in strengthening a building will meet these performance purpose of conservation must be to retain this and the straw will, itself, become a telling feature in the criteria which fall within practical and aesthetic evidence. But the artefact encapsulates scientific quality of the surface. It may be coated with a hardened dimension. The intervention will be: information. Fragments of organic material permit mud, perhaps containing a calcareous material such as i. economical- a practical dimension; ii. it will be dating by the measurement of atomic decay- the crushed lime or chalk. It may have been coated with a durable: also a practical dimension; iii. it will be Carbon 14 technique. Other analytical techniques material based on burned lime, at the simplest a lime effective in its designated use – a further practical include Thermoluminescence and Optical Dating, both wash, providing decoration and a coating weather dimension; iv. it will be sympathetic or visually of which use the effects of long burial to provide resistant qualities. acceptable – an aesthetic consideration; v. it will be alternative methods of dating by sampling. Other The handworked nature of such operations has given a explicit – an ethical and aesthetic consideration; techniques are known but little used – such as the special quality to such walls, many of which defy the vi. it will retain historic values – an ethical qualitative measurement of saline impregnation; others normal rules of level and plumb bob, being battered consideration; vii. it will not diminish the authenticity of have yet to be perfected or even to be discovered. The back as they reduce in thickness with height to shape monument – also an ethical consideration. analysis of soil particles and airborne deposits such as the building, curving and being modelled with subtle If these criteria are met the investment in strengthening pollen can provide evidence of conditions and dates of contours that suit the hand and please the eye. Such will be a success. construction. These and other forms of scientific buildings with natural organic shapes possess special Restrengthening of a structure must achieve an analysis provide information on sources of material qualities of their own which are best and, perhaps only immediate objective in restoring or enhancing the and distribution of the origins of materials which in the able to be perpetuated by the same methods as were ability of the construction to perform the task required long future of conservation will add to man’s used to create them. The batter or inward inclination of it. It must also be given longevity consistent with knowledge of the past. The loss or destruction of such frequently given to walls built in unbaked earths reflects acceptable costs. In practical terms the building must evidence is to be deplored. the natural instincts of the builder in handling material work well: in aesthetic terms it should please the user Conservation can serve one further purpose, sometimes of uncertain compressive strength and although earths and viewer. In ethical terms its retention is important treated as a justification; the economic utilisation of the under suitable compaction can achieve remarkable because it is tangible of the past. It is a surviving structures. As has been discovered by many builders in values in compression, their tendencies to become artefact. the past it can be less expensive to reuse a building fissiparous mean thet they are relatively weak structures - The visual quality of the structure may be enhanced or than to build anew. The adaptation of historic structures in tension, capable, nevertheless of being carried to diminished; to new or enhanced usefulness is often a economic heights of 30 m.; but it is out of this characteristic that - The interpretation may make a positive statement in ground for conservation. Earths and brickwork are the need for massive lower courses derives and hence terms of method, or time and of its funcion. massive and involve substantial labour. Patination and the tendency of builders towards the use of a batter - It may also enhance or alter the function of the the maturity of age are qualities which they gather and (inward slope) rarely found in more robust forms of structure.