A2 – Dressed Quarry Stone Wall

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Building techniques : A2 – Dressed Quarry Stone Wall

Coutry: Lebanon

PRÉSENTATION

Geographical Influence

Definition

Dressed quarry stone wall

- traditional masonry tools: chisel, picks and hammers.

- 4, 5, 6 faces-sometimes 2 faces

- naturally squared.

- stone laying with or without wedging.

- stones are laid straight, same size or not.

- mortar laying

Environment

In the MEDA area, we find dressed quarry stone in all environments: urban, rural, in mountain, plain and sea side. Its presence is generally common. In Lebanon, dressed quarry stone (Moqassab) is often used everywhere: rural environment, urban, plain, mountain and sea side.

Illustrations

General view: Details close-up:

This project is financed by the MEDA programme of the European Union. The opinions expressed in the present document do not necessarily reflect the position of the European Union or of its member States. 1/8

A2 Lebanon – Dressed quarry stone wall

CONSTRUCTION PRINCIPLE

Foundations Illustrations

Finding a "firm base" or “good ground” is a preliminary for the builder. If rock shows on the surface, the wall is built directly above. If not, all countries dig a small trench (~ 50 cm deep), practically never deeper than 1m. the width can be equal to the thickness of the wall above-ground, but it can also be up to twice this thickness. Combination of 2 factors : width of the trench and type of filling materials: adjustments and adaptation to each spot and ground. The materials are always stony: the trench is filled with stones, generally linked with mortar. If the module is small, the trench is broader. Several countries reported construction over ruins used as foundation. In Lebanon, dressed quarry stone walls are built either directly on rocky ground, or a trench is dug if the ground is loose. The foundation is filled with a coarser rough stone masonry, laid in mortar, slightly broader than the thickness of the wall, and reaches solid ground level.

Construction Materials

Type and hardness To build dressed quarry stone walls, you must avoid using stones that might flake. The first quality for stones is also that they be easy to cut and face : that is why limestone is commonly used in the thirteen studied countries. It is usually semi hard, around five on a scale from 1 to 10. (1=chalk, 7 to 8= marble, 10=granite ). After limestone, we find basalt (Cevennes in France, the Jordan Valley in the Middle East) and finally sandstone (in Spain, France, Tunisia), or granite. In Lebanon, for dressed quarry stone constructions, limestone (reported hardness: 4 to 6), basalt in the areas of Akkar, or dune sandstone "Ramleh" in certain Littoral zones. The hardness of limestone depends on the origin and extraction depth of the limestone used, filled with earth and rubble (gravel...) for walls with two linked facings.

Modules Modules of all sizes can be found. Thus, throughout the Mediterranean area, blocks are 12 to Construction principle: materials and 80 centimeters long, 8 to 40 cm high and 15 to 60 cm deep. Blocks may vary substantially in modules. View of building boat in dressed volume from 2 liters to 100 liters. These blocks can non-the-less be handled by a few men. quarry stones This being an important characteristic for dressed quarry stone walls (rough for dressed quarry ) as opposed to six faced ashlar. The following correlation has been observed : large modules are usually soft stone and not very dense (Israel = 80 x 30 x 40, hardness 3), small modules are harder and heavier stones. In Lebanon, the dimensions of dressed quarry stones are: length, between 20 and 70 cm (variable); course height, between 24 and 30 cm; depth, between 20 and 35 cm.

Mortar laying

Realisation / Construction : Dressed quarry stone walls are always laid in mortar. The ingredients generally found are: lime + sand (sometimes + gravel or + broken tile or + crushed stone powder), earth + straw, earth alone. In Lebanon, dressed quarry stone masonries are laid in mortar with lime mortar.

Binding material : Detail of material The two binders used for the realisation of dressed quarry stone masonry throughout the studied countries are either lime, or earth. In Lebanon, the binding material used for the mortar of dressed quarry stones is lime.

Agregate – grading : The aggregates are sand, gravel, broken tile and coarsely or finely chopped straw. In Lebanon, the aggregates used for the mortar of dressed quarry stones are sand, earth and gravel. Ashes and broken tile are sometimes also added.

Dose ratio : The grading of these aggregates varies according to kind from 0-3 mm to 0-12 mm. In Lebanon, the reported dose ratio for the mortar of dressed quarry stones is of one volume of binding material for 3 volumes of aggregates.

Associated element

A2 Lebanon – Dressed quarry stone wall

CONSTRUCTION PRINCIPLE (CONTINUED)

Mortar laying (continued) Illustrations

Dose ratio : One volume of mortar contains from 15% to 50 % of binding material, lime or earth. Fat mortar can be used (40% to 50% of binding material in the composition), depending on the aggregate used: if only one type is used, and if it is fine, than the volume of mortar binding is increased. Exceptionally, a second or third aggregate can be added to thin down the dose ratio (20% to 33%). In this case the aggregate grading is more elaborate and integrates fine elements (stone powder, ashes), average size elements (sand, broken tiles) and large elements (gravel, chopped straw). This art of combining inert mass materials saves on binding material and optimises its use. For modest buildings, cradling mortars are usually more slack than for facings: they are not measured out as precisely and earth usually partly replaces lime. This is obviously done for economical reasons. In Lebanon, the reported dose ratio for the mortar of dressed quarry stones is of one volume of binding material for 3 volumes of aggregates.

Thickness and Dimensions

This construction technique leads to building thin walls: 25 cm (exceptional) to 45 cm, and very thick walls, 45 cm to 100 even 120 centimeters. In the first case, the stones on each facing of the wall are fitted one against the other, alternating one long with one short. In the second case, for thick walls, the stone facings are separated with filling. This filling can be made of smaller elements of the same type: rubble, quarry waste, broken tiles or broken bricks etc., or mortar alone. Sometimes header binder will joint two facings more efficiently. Sometimes the builder makes the wall wider at each floor level. This traditional type of wall makes it possible to construct substantially high buildings (16 m or Construction principle: wooden lintel more). The corresponding thickness can vary by 10% (60 centimeters for 6 m in height ) up to 50% (75 cm for 15 m in height). Up to four levels, 60cm are enough, beyond we find a thickness of 80 to 120 cm. Common constructions do not have more than six levels. Greater heights are exclusively found in urban areas. In Lebanon, the technique of dressed quarry stone walls consists in building masonries whose thickness varies from 40 to 60 cm for the single linked facing walls, and between 60 and 120 cm for double linked facing walls. In the case of double linked facing walls; the two facings are linked with an intermediate filling: a mixture of lime mortar and more or less large aggregates. Header binder stones are laid to ensure the linking of this two row masonry. The maximum height of dressed quarry stone constructions on one level is approximately 4 m for simple walls. The height is variable for the double linked facing walls. It depends on the type of associated floor. The thickness of a wall associated to a metal beam floor out is around 60 cm, whereas it easily reaches 100 cm when the wall is associated to a vault.

Finishing Aspect

There are four possible finishing coatings: keeping the wall bare either as constructed or joint, wall slightly lime-washed, wall totally covered with rendering and finally wall with rendering and lime-wash. There are two distinct reasons for choosing finishing coating: The first is aesthetic : giving priority or not to the regularity and homogeneous aspect of the Windows and openings facing leads to leaving the wall bare, painting or rendering it. Deciding to leave the wall bare depends on whether the quality of the material is suitable or not. The second reason is practical. The rendering is a means of protection for the facing of the wall. The choice noticed today is not necessarily the original one, it may have varied in time through restoration campaigns led for maintenance reasons or influenced by style and fashion. This kind of wall is finished with lime, earth or a combination of lime and earth. Lime washing is usually made with lime, sometimes tinted with color. In North Africa, plaster and white clay are sometimes used. In Lebanon, dressed quarry stone masonries have rather regular courses, and are generally left bare. They are only pointed. The external walls can be pointed, and then washed with lime. The interior walls are rendered with earth or lime and then whitewashed with lime.

Associated element: niche

A2 Lebanon – Dressed quarry stone wall

CONSTRUCTION PRINCIPLE (CONTINUED)

Tools

Masons use traditional tools for building this kind of wall (wheel barrow , trowels, brush, plumb line, chisels, float, drift pins etc.), no other specific tool has been reported. In Lebanon, stone cutting tools (Dabboura, Chaqouf... etc have) or mason tools, no specific tool was reported for the construction of dressed quarry stone walls.

Trades

In every country, all masons can build this type of wall. However, this technique is on the borderline between a stone cutter, who can carve 6 faces, and the mason, who can dress faces. Sometimes, one first cuts the blocks in the quarry and then mason carries out the laying. To Lebanon, the realisation of dressed quarry stone walls is mainly entrusted to a mason, helped by stone cutter.

Thermal and Acoustic Performances

For dressed quarry stone constructions, limestone is most commonly used (followed by basalt, sandstone, and granite): the thermal and acoustic performances are reported from good to very good by all the studied countries. The ingeniousness of the builders developed ventilation systems: they vary the thickness and thus the mass of the walls, according to the nature of material used, producing the greatest possible inertia. This was naturally sought to obtain a maximum thermal comfort for dwellings, dimming temperature amplitude between hot and cold seasons, day and night, which can often be quite significant in the Mediterranean area. This mass also improves acoustic quality. In Lebanon, dressed quarry stone constructions are considered satisfactory from a thermal and acoustic point of view. Three factors contribute to this result: the reflective clear colour of limestone (different stones can be rendered or whitewashed), the masonry thickness, and external renderings + interior protection.

Ageing pathology

Linked to materials and climatic conditions: For construction in dressed quarry stone, pathology is very much linked to the stone used, and whether it is more or less porous, thus more or less sensitive to the attacks of water and salts. Generally, rain water infiltration and capillary increase seem to be the main causes of disorders or deterioration noted : deterioration of the pointing mortar, specific masonry disjointing, hollowing out in evaporation pockets for porous stones. The other forms of moisture which deteriorate the masonries are little evoked by the partners, particularly splashing at the foot of wall and condensation. Moreover, a lack or slack checking of the state of piping, drainage, wells, cisterns are reported as worsening factors.

Linked to the technique : No ageing pathology linked specifically to the dressed quarry stone technique was reported. In the event of faulty header binders with vault thrust, one can however see a separation of the two rows of stones. In Lebanon, the ageing pathologies described for dressed quarry stone constructions are those commonly reported by partner countries. They are at both related to the quality of the aggregate used, more or less soft limestone, or dune sandstone vulnerability to honeycombing as well as the quality of the mortars and pointing, the layers of protection (wash and/or rendering). The care brought to implementation of this technique is of primary importance, as well as the choice of materials: the alternation of different stones accelerates the deterioration of soft stones: the harmful effects of water and moisture are not to be neglected.

A2 Lebanon – Dressed quarry stone wall

CONSTRUCTION PRINCIPLE (CONTINUED)

REALISATION DESCRIPTION

In Lebanon : (Text in French)

La construction en pierre taillée équarrie s'effectue habituellement pendant les saisons de printemps et d'été, par temps sec. Le maître maçon "Moallem" est secondé par un apprenti. Ils sont aidés par 2 à 4 ouvriers pouvant d'ailleurs faire partie de la famille du propriétaire de la maison, dans le cadre d’une entraide “Aouné” si cela se passe dans un petit village. Un ou plusieurs tailleurs de pierre sont parfois également nécessaires. L’approvisionnement en eau est prévu à l’avance bien avant le début des travaux.

Les moellons calcaires extraits de la carrière sont amenés sur le chantier. Les blocs trop irréguliers sont rectifiés par le tailleur de pierre. Les dimensions, agencement des espaces, ouvertures et autres modalités de la construction sont décidées conjointement par le maçon et le propriétaire. L’emplacement des murs est marqué en premier au sol par le maçon pour permettre aux ouvriers de creuser les tranchées de fondation qui doivent atteindre le "bon sol".

Après avoir vérifié avec son apprenti la profondeur des tranchées, le maçon demande aux ouvriers d'apporter les pierres, les moellons et le mortier de hourdage nécessaires pour la pose de la première assise de la maçonnerie de fondation.

Ensuite les pierres d’angles de la construction ainsi que l'emplacement des ouvertures sont fixés à l’aide de fil à plomb et au cordeau pour contrôler l’alignement. Le travail d'élévation du mur se fait systématiquement. Le maçon fixe le niveau et positionne les moellons dans le mortier en alignant l’arête supérieure du moellon au cordeau. Un soin particulier est octroyé à l’alternation des pierres longues et courtes et au croisement des joints. L’assistant apporte les pierres adéquates et le mortier au maçon. Pour les pierres brutes ou équarries, la face présentée est celle qui offre le plus de régularité, de planéité et de surface. Pour les murs à double parement « Qalline », des élements en boutisse sont incorporés à fur et mesure de la construction et du comblement par les ouvriers du vide entre les deux murs par des moellons, du gravier, du tout-venant, de la terre et du mortier. Le mur extérieur étant réalisé avec des pierres équarries et le mur intérieur destiné à être enduit des moellons.

Dans certaines régions du Liban comme la békaa et le Nord, des poutres en bois sous formes de chaînage horizontal sont incorporées dans le courant du mur à proximité des angles et au dessus des linteaux des ouvertures.

Les tailleurs de pierre préparent les pierres en fonction des besoins. L’un se charge des pièces particulières (comme celle des jambages, linteaux et pied droit), l’autre réalise les modules de base pour le courant du mur.

La réussite technique de la construction de ce genre de mur est tributaire de l ‘habileté du maçon, de la qualité et dosage du mortier de chaux, ainsi que de la qualité de la pierre et des matériaux de remplissage.

Le rejointoiement des joints est effectué après la construction du mur, elle est suivie par l’application d’un enduit de chaux ou d’un enduit de terre badigeonné à la chaux sur le parement intérieur.

A2 Lebanon – Dressed quarry stone wall

ASSOCIATED WORKS

Angles and Columns Illustrations

Angles: Possible processing in the technique, by using same materials Generally, no specific processing of the angles was reported for dressed quarry stone constructions. It is generally noted that the angle masonry is reinforced with an anchoring with larger module blocks than those used for the walls. Sometimes, they are more carefully cut so as to obtain more regular faces to ensure a better course and a cleaner edge to mark the right angle. The same stone or another kind of stone, harder than that of the walls, is sometimes used. This material change also shows an aesthetic concern, playing with the contrast of colours between the masonry of the walls and the angles. When constructions are protected with a rendering, the angle can stand out with a different tonality or finishing than the rendering. Decorative elements (posts, carved stones...) are sometimes integrated. In urban environment, that the ground floor wall angles are frequently chamfered to 45° or rounded so as to ease traffic in the very narrow lanes. In Lebanon, the angles of dressed quarry stone constructions can be built like the wall course; the angles are distinguished by a different processing of the surface: a relief harping, protruding approximately 4 cm from the bare façade or with a change of texture, type of stone or colour.

Colunms: Possible processing in the technique, using the same materials The stone used for the walls generally allows for pillar construction when it is sufficiently hard to withstand the loads. All alternatives are found : in the same modules as blocks, quadrangular or round, in solid stone or paving + filling. The thickness of a pillar is seldom under 60 cm. In Lebanon, the dressed quarry stone technique allows for the construction of pillars, solid or hollow (then filled with a mixture of mortar and gravel, as for a double linked facing wall). The use of traditional monolithic columns is also reported for arcades and verandas.

Windows and Openings

Lintels and Arches: Lintels and arches are found everywhere in the MEDA area. Several types of lintels are met: 1 Single element, rough or squared wood element, branches juxtaposed lengthways, monolith stone more or less well squared, sometimes carved. It crosses the width of the opening and rests on the jambs. 2 Separate elements, stone or brick arch. It can be surmounted with a relief arch (or exceptionally as a “bâtière”) made up of several stone or brick elements which better defer loads on the jambs. Practically each country exploits three solutions: Single element lintel (stone or wood), with or without relief arch, the arch in separate elements, round or flat elements. In many cases, the lintels are mixed: stone on the outside of the wall, wooden on the inside face. In some countries, like Cyprus, France, Greece and Portugal, lintels are made with terracotta brick with or without relief arch. Jordan and Palestine only reported stone for lintels. Associated elements: treatment of angle In Lebanon, the lintels are stone slabs, single or separate elements, with or without relief arch. Beams or wooden trunks (local wood, i.e. mulberry tree) are used as lintels, and as thick as the opening in the wall.

Window

Lintels

A2 Lebanon – Dressed quarry stone wall

ASSOCIATED WORKS (CONTINUED)

Windows and Openings (continued) Illustrations

Jambs The jambs are generally assembled in the course of the wall, with same material and the same technique. They sometimes consist of one or more stone elements, carefully cut with sharp edges, protruding or not, sometimes profiled or carved, protruding or not on the masonry. A structural body, the jamb sometimes consists of harder stone, sometimes even of another type of stone. Changes of material and consequently of colour are undoubtedly also an aesthetic concern. A rendering rarely covers the framing masonry of the opening. This does not apply when jambs are made with ashlar. In Lebanon, the jambs are often built like the course of the wall. They can be also carried out in one or more stone elements, sometimes of a different nature than the masonry, allowing for a decorative processing or a change in tones.

Supports Non-protruding supports are most frequent. Five countries reported and illustrated protruding supports. In Lebanon, in dressed quarry stone constructions, the supports are generally non-protruding.

Dimensions The technique of dressed quarry stone construction does not impose any specific size constraints for openings. The opening is generally a vertical rectangle. Its dimensions can vary in width from 10 cm minimum to 200 cm maximum and, from 15 cm to 300 cm maximum in height. From ventilation openings to barn doors, the width/height ratio is 1/2 to 1/8, sometimes 2. In Lebanon, in dressed quarry stone constructions, the dimensions of openings vary from 60 to 120 cm in width and from 60 to 120 cm in height for one linked facing walls, the standard is 60 cm wide for120 cm high. For double linked facing walls (more common), dimensions of the openings vary from 60 to 180 cm in width and from 80 to 180 cm in height, the standard is Wall-roof connections : acroters then 80 cm wide for 180 cm high.

Associated Elements

In the MEDA area, Algeria, Portugal and Turkey describe corbelled volumes on the façades. Later added balconies, buttresses, protruding elements, circulation galleries on the 1st floor of dwellings, overhanging support trunks for floors or roofs, and waterspouts through acroters are the main associated elements mentioned by the partner countries. In Lebanon, besides gemelled windows, flower vats, waterspouts, bull’s eyes, no specific associated element was reported for dressed quarry stone constructions.

Wall – roof Connections

In the MEDA area, when the roof is sloped, dressed quarry stone runoff walls are generally protected with an overhanging roof, variable in length (rafters, boards supporting / withstanding roofing material). Almost everywhere, flat stones, fired brick or stones are reported, laid in corbelling on the top of the walls. For flat roofs, either the wall is prolonged with a more or less high acroter, thus enclosing the flat roof, the roof protection rendering falls overhangs onto the higher part of the external walls, or a system projects rainwater away from the walls. In Lebanon, for dressed quarry stone walls, often reported overhanging cornices with profiled stones, add elegant curves to the construction.

Pathologies and disorders: cracks, transformations …

A2 Lebanon – Dressed quarry stone wall

USE, EVOLUTION AND TRANSFORMATION

Use

Types of buildings The dressed quarry stone technique walls is used mainly for apartment buildings and annexes, but also for public and religious buildings. In Lebanon, the dressed quarry stone technique is used for all types of buildings.

Period when the technique first appeared – Period of use – still used today or disappeared This technique been used since Antiquity, sometimes even earlier. With the exception of Greece, it is disappearing practically everywhere, or has already vanished, according to countries, in 1940, 1950 or 1960. However, it is still sometimes used for the restoration of certain buildings. In Lebanon, the dressed quarry stone technique has been used since Antiquity. It was used until the middle of the 20th century (1940s). The incorporation of the wooden beam anchors was reported in construction trades since Persian times (site of Jbeil).

Reasons why the technique disappeared or has been modified : In the MEDA area, the reasons evoked for the disappearing of the rough stone technique are most frequently the appearance of new materials considered as easier to implement; the high cost of skilled, little requested labour, rarefies this process, and leads to a disappearing of the know- how, from the construction technique point of view as well as maintenance. In Lebanon, the reasons for the disappearing of this technique are those commonly mentioned by the partner countries.

Evolution / Transformation

Materials Dressed quarry stones are produced in the same way: the stone beds are either sawn with machines or else the blocks are extracted and then sawn courseways. The facings are also sawn with machines: their role is decorative. The aspect is different because the edges of the blocks are parallel and straight. In the construction business, they are replaced by industrial materials, blocks, concrete blocks, terracotta, porous concrete. Modules are all identical: specific parts are made for corners, lintels and any other particular piece. They are assembled in one row, variable in width, and tightened with reinforced concrete. In certain cases, stone plating imitates the aspect of traditional techniques. In Lebanon, limestone and Ramleh stones are still used but for facing only. It is cut directly mechanically at the quarry, or recovered from demolition sites: 5 cm thick and 25-30 cm courses. The traditional mortar, a mix of lime, earth, gravel and broken tile, is now replaced by a mixture of cement, gravel and sand. Hydraulic lime powder is common on the market. Hydraulic lime powder is common on the market; however air lime in rock or paste form (fat lime) is available only upon request. The use of traditional mortar is reported only for restoration building sites of.

Technical aspects This kind of building does not require much tooling. Today, mechanical means help for handling, supplies, transport and lifting. The mortar is mixed in a concrete mixer. Laying modern materials is similar to stone laying: the only difference is that it is built in one row instead of two linked rows. In Lebanon, traditional dressed quarry stone constructions are now replaced with rough stone masonries, with external facings 5 cm thick, hollow cement blocks, 15 to 20 cm are covered thereafter with a 2 cm thick rendering: rough stones with a concrete pointing on their interior facing.

Evaluating materials and replacement techniques: -Materials are reliable for conservation if they can withstand the loads. Resistance may vary according to the kind of materials used: (Cement/terracotta/porous concrete), difference in width, and depending on if materials are hollow or full. This also applies to building transforming. -These materials are much more economical than traditional stone masonry. -Depending on the materials chosen there can be a substantial difference as far as thermal insulation is concerned. Width also influences performance. Thermal insulation can be added at the same time. -As regards aesthetics, the issue is related to thickness: older buildings are 0.60m wide or more and this is very obvious for openings (windows and doors). For old buildings, replacing with modern blocks is only satisfactory if masonry is then coated with finishing. For new buildings, particularly private houses, these replacement techniques are no longer used. In Lebanon, the replacement technique for traditional dressed quarry stone constructions is considered satisfactory aesthetically; it is also economical but suffers from pathologies like moisture and thermal irregularity.