building a3 – rough stone wall with mortar · a3 lebanon – rough stone wall with mortar this...

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. 1/9

PRÉSENTATION

Geographical Inf luence

Definit ion

Rough stone wall - Little or no stone cutting. - Shape: from random to pseudo quadrangular - Origin: quarry, loose stones and rubble, mountain torrent stones - Courses: from irregular to almost straight courses (according to the shape and regularity of the rough material) - Laid in mortar with or without large wedged elements, with or without filling of the joints with small elements.

Environment

In the MEDA area, with some exceptions, one notes the use of rough stone, laid in mortar in all the environments: rural, urban, plain, mountain and seaside. It's common everywhere. Alternatives to this technique associating more or less sophisticated systems of anchoring with wood or bricks were described by Algeria, Egypt, Greece, Morocco, Tunisia and Turkey. In Lebanon, the rough stone with mortar technique is often used in rural environment, plain and mountain.

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General view : Detail close-up :

Building techniques :

Country :

A3 – Rough stone wall with mortar

Lebanon

A3 Lebanon – Rough stone wall with mortar


CONSTRUCTION PRINCIPLE

Foundations

Looking for the "good ground" is a precondition for the builder. If the rock shows on the surface, the wall will take support directly on it. If not, all the countries dig a trench; the depth varies from 30 cm minimum, to exceptionally 120 cm maximum; the average ranges between 50 and 70 cm. Three points characterize the foundation masonry : 1. its width which can be equal to the thickness of the wall; it is however often more than 20 cm. 2. the type of materials that constitute it; 3. when the level of the ground is unequal, the height of the foundation wall can be extended in a base plate which can exceed the meter. The materials that furnish the trench are always stony: crushed stones or stones, flat stones, from pebbles to almost perfectly squared rough stones that can reach 40 cm side. The nature of the stones used in a foundation is sometimes voluntarily different from that of the stones used for the wall above-ground (harder stones, more regular, less porous...). These materials are generally linked with a well proportioned lime mortar, with a mortar of rubble earth or mixed earth + lime. A gypsum / plaster is reported by Algeria and Tunisia. Generally, the description of foundation systems implemented traditionally by all the countries reflects the need for ensuring a stable course for the construction, distributing loads on the original ground in the most adequate and economical way possible. In Lebanon, before the construction of rough stone walls, a trench is dug to reach the "good ground". The foundation is a double thickness: two facings of large rough stones linked with an intermediate filling: a mixture of lime mortar, earth, gravel and rubble. The foundation wall is always thicker than the wall above-grade.

Building Materia ls

Type and hardness : In the MEDA area, to build with rough stone, one uses all the types of stone including those that can break or split (schist in particular ). Limestone is the stone most used in all the countries. Its hardness varies from 2-3 (for the Tunisian " Toub " by ex.) to 8-9 in Cyprus. (Short of a common standard on hardness, we considered a scale from 1 to 10 as follows: chalk = 1, marble = 7 to 8, granite = 10). After limestone, we find sandstone, schist, basalt, granite and pebbles from torrents. For horizontal anchoring in wood, according to the availability, one uses oak, cedar, chestnut, pine of Alep and palm tree but also juniper and apricot tree. In Lebanon, for rough stone walls, one uses limestone (reported hardness: 4 to 6). Hardness depends on the origin of the limestone used and extraction depth. In certain areas in the North (Aakar) basalt is very common for this kind of wall. Modules Rough stone's main characteristic is to exist in all the possible shapes: from irregular to almost regular. All dimensions are thus found. In the MEDA area, according to the nature of the stones available locally, the length of the blocks varies from 10 to 50/55 cm, the height of a course from 2 to 25 cm, and the depth from 10 to 35/40 cm. Rough or squared stones in particular are distinguished from dressed/cut 6 faces stones by the fact that they must be handled by a single man without any means of lifting. When the stones extracted from the quarry are too large and thus too heavy, they are simply broken with the pickaxe. According to species of wood used, the anchoring is short or long (from 50 cm to 2,50 m maximum), rough or squared, with sections (for those reported) between 5 and 12 cm. In Lebanon, for rough stone walls, the length of the blocks is variable; course height is 20 to 30 cm and depth, from 20 to 35 cm. The rubble stones used as blocking elements vary in dimension.

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Construction principle: details

Windows and openings: doors with wood lintels



CONSTRUCTION PRINCIPLE (CONTINUED)

Mortar laying

Realisation / Construction: In the MEDA area, the composition of the mortar for rough stone walls is: - lime + sand To this mixture, one often adds a second, third, sometimes even fourth inert aggregate: gravel, broken tile, rubble stone, ashes - lime + earth (+ possibly sand) - earth + straw - earth alone In Algeria and Tunisia, one uses traditional local gypsum alone(+ possibly sand). In Lebanon, the rough stone walls are laid in mortar with lime mortar. Binding materials : In the MEDA area, the two traditional binders in the composition of mortars for rough stone are earth and lime. In Algeria (in M'Zab) and in Tunisia (in the area of Nefzaoua), local gypsum based plaster is used traditionally as binding material. In Lebanon, the binding material used for rough stone mortar is lime. Aggregate : In the MEDA area, the aggregates used traditionally in the composition of mortars for rough stone walls are: sand, gravel, broken tile, quarry run, coarsely or finely chopped straw and sometimes earth. Exceptionally, ashes are found. In Lebanon, the aggregates used for rough stone mortar are earth and gravel. Ashes and broken tile are sometimes also added. Aggregate-grading : The grading of the mentioned aggregates varies according to their nature from 0-3 to 0-12 mm. In Lebanon, for rough stone mortar, the grading of the aggregates varies from 0 to 9 mm. Dose ratio : In the MEDA area, for rough stone masonry, the mortars containing lime are as frequent as those containing earth. The idea of volume of mortar used for this type of masonry is significant. According to whether the stones present quasi regular or very irregular shapes, consumption of mortar can respectively vary from 4 to 25% of the volume of masonry, sometimes even to 50%, in Egypt, in the area of Siwa, for salt stones called " Kershif ". In these very consuming cases, this mortar, moreover generally containing earth – as it is much more economical – is also used for pointing and sometimes the surplus is spread out over masonry as protection rendering. Mortars containing lime are thinned down by the addition of aggregates; small (sand, broken tile) and large (gravel, quarry rubble, chopped straw). These inert loads make it possible to spare binder; this concept of economy is still present nowadays. The reported dose ratio for the majority of countries, for mortar containing lime is 1 to 2 volumes of binder for 3 to 4 volumes of aggregates. The dose ratio for earth mortar when it is combined with straw is practically never specified; it is the experience of the builder which determines this ratio. In Lebanon, the reported dose ratio for rough stone mortar is 1 volume of binding material for 3 volumes of aggregates.

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Windows and openings : examples

Finishing Aspect: internal lime rendering




Thickness and dimensions

In the MEDA area, rough stone walls are a simple or double thickness, according to the length of the stones available locally and if they are transportable manually. For walls with a simple thickness, either only one row of block elements makes the two facings, or stones laid in header binder form, to ensure the linking of two rows of masonry. In this case, the reported thickness varies from 30 cm minimum to 50/55 cm maximum. For walls with a double thickness, the two facings are linked by an intermediate filling composed of a mixture of coarse mortar and quarry rubble. The introduction of horizontal anchoring, wooden or brick (less frequent), regularly distributed in the masonry, improves the construction performances of the wall. These systems of anchoring also allow: • to compensate for the irregular shapes of the stones by course correction; • to bind the two facings by transverse parts, making up blocks elements; • to bring more cohesion and stability, and thus allow to build thinner walls and to raise higher walls; • to withstand seismic quakes without compromising the balance of construction, in the areas this concerns (the Eastern Mediterranean). The thickness of the walls with double thickness without anchoring varies from 55 to 100/120 cm maximum; with anchoring, from 50 to 60 cm sometimes even exceptionally 100 cm. When rough stone constructions have floors, most countries reported a thinning down of the wall to limit downward loads and a sizing per level according to what is built or installed on top. If the stability of masonry is precarious and in the absence of a system of horizontal anchoring, the height of the walls is limited to 3-4m. If not, according to the quality of the equipment and the ingeniousness of the horizontal anchoring system, the height of the walls varies between 6 and 12 m (maximum thickness at the base of the wall without anchoring = 80 to 100/120 cm, with anchoring, 50 to 60 cm). Exceptionally 15m high constructions. These great heights are reserved for housing in urban environment. In Lebanon, the walls built with this technique are from 40 cm to 60 cm thick, maximum. The masonries can be a single linked facing, or a double linked facing. When double, the linking is held by header binder stones and /or an intermediate filling made of rubble and coarse mortar. In certain areas of Bekaa, double walls laid in mortar are next to interior walls carried out with mud brick. Rough stone constructions laid in mortar usually have one level only. The height of the wall is around 4m.

Finishing

In the MEDA area, rough stone walls are either left bare when the courses are very regular, pointed (hollow, with relief) or not, or protected by a simple lime wash , or partially (rendering with apparent stone ) or completely covered with lime rendering, earth or lime + earth. These various types of rendering can also be covered with lime earth or organic wash. Besides, this wash often is the layer of maintenance for the rendering. Contrary to the walls in dressed quarry stone or dressed/cut stone with 6 faces, the decision of finishing rough stone masonry results mainly of functional intention. According to the nature of the stones used, the quality of equipment, the wood species used for the horizontal systems of anchoring, of the mortars and pointing, a rough stone wall is more or less vulnerable to water. The wash and/or the rendering ensure its protection. The aesthetic concern is generally secondary. It is often limited to the choice of colouring the maintenance washes or not. In Lebanon, the rough stone masonries are left bare, and are only pointed, when the course is very regular. If not, in most cases, the external walls are washed with lime after being pointed. When stones are really too irregular, the masonry is protected with rendering. A rendering of earth or lime covers the facing of the inside wall.

Tools

In the MEDA area, no specific tool, common to all the users was reported for the building of rough stone wall . The basic common tools are all extremely simple: plumb line, level, chalk line for the geometry, trowels for the mortars, percussion tools when needed to reshape the stones. In Lebanon, besides the basic tools of the mason, no specific tool was reported for rough stone constructions.

Trades

In the MEDA area, rough stone constructions are usually carried out by a mason sometimes accompanied by a stone cutter(for the angles, lintels, jambs) and exceptionally by a carpenter (for the horizontal wooden anchoring systems ). In rural environment, certain countries specify that according to local tradition, the future inhabitant, his family and villagers help the mason. In Lebanon, it is the mason who builds rough stone walls. He is helped, when necessary, by a stone cutter who cuts elements for the framing of openings or certain structural parts of the wall.




Thermal and Acoustic Performance

The quality of the thermal insulation varies mainly according to the nature of aggregate materials used and the thickness of the masonry. In the MEDA area, all countries reported satisfactory thermal performance for their rough stone constructions, with often thick walls except for constructions out of granite, basalt and other compact rocks that are 3 poor heat insulators. The ideal performance is obtained by a porous material (calcareous) combined with a thickness greater than 60 cm (2 qualities allowing to accumulate heat at sunny hours) and with a strong variation in temperature between day and night (the wall restoring the heat stored during the hot hours of the day during the cold hours at night ). This technique of construction is also favorable to acoustic quality because of masonry thickness. In Lebanon, rough stone constructions laid in mortar are considered as satisfactory from a thermal and acoustic point of view. Three factors contribute to this result: the limestone, the thickness of the masonry and the external and interior renderings.

Ageing pathology

In the MEDA area, the ageing pathologies described by the majority of countries are related to the materials used, the technique of implementation and climatic conditions. The worst enemies of rough stone walls are water and earthquakes. The harmful effects of splashing rain but also infiltration, capillarity (the phenomenon of condensation is never quoted by the partners) involve, when they exist, a deterioration and separation of the protection layers (wash, rendering), the more or less serious degradation of stones, according to their nature, and the loss of the pointing and mortar. Moreover, worsening factors impair the quality of verification: lack of checking of piping, sewage networks, wells, water tanks. Structural disorders are then inevitable (cracks, specific breaking up of the masonry...). A sagging at the angles is frequent when they were not specifically consolidated. From a seismic point of view, the principal risk is brutal splitting. To avoid or limit this phenomenon, the countries concerned developed astute systems of horizontal anchoring ,most frequently wooden. They have reported that without protection, the wood gets substantially damaged with time, outside (bad weather) as well as inside (moisture). In Lebanon, the ageing pathologies mentioned for rough stone constructions laid in mortar are those commonly observed by partner countries. They are both related to the quality of the aggregates and materials used, here more or less hard limestone, the quality of the mortar and pointing, and the layers of protection (wash and / or rendering).




REALISATION DESCRIPTION In Lebanon : Rough stone wall with mortar with and without wooden branches. (Text in French) La construction en pierre en pierre brute hourdée 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 s’agit d’un petit village. Un tailleur de pierre est parfois nécessaire pour la taille des éléments destinés aux encadrements et à certaines parties structurantes du mur. 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 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 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, l’alignement des arêtes supérieures du moellon n’est pas nécessaire. De temps à autre le maçon peut effectuer une assise de réglage pour rétablir le niveau. Un soin particulier est accordé au croisement des joints. L’assistant apporte les pierres adéquates et le mortier au maçon. Pour les pierres brutes, la face présentée est celle qui offre le plus de régularité, de planéité et de surface. Pour les murs à double épaisseur, des éléments 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. 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. Le tailleur de pierre se charge des pièces particulières comme celle des jambages, linteaux et pied droit, encadrements, etc. 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.



ASSOCIATED WORKS

Angles and Columns

Angles: Possible treatment in the technique, using the same materials In the MEDA area, in all the countries, angles are built like the course of the wall which lead to specific structural disorders for rough stone walls without a system of horizontal anchoring. It is noted however that the builders are generally very attentive to the stability of this particularly solicited spot: the corners. The process often mentioned is a vertical anchoring carried out with stones of greater dimension, cut more carefully to ensure a better course, and with a more or less sharp edge to enhance the right angle. The stones used can be the same or of another nature than that of the walls but sometimes harder. Decorative elements (column, carved stone...) are sometimes integrated. The horizontal wooden anchoring system, when used, always includes a reinforcement system of the angles, according to the local tradition of construction. In urban environment, the corners of ground floor are often chamfered at 45° or rounded so as to facilitate traffic and circulation in very narrow lanes. In Lebanon: an anchoring of the angles is generally carried out with larger stones, dressed or even carefully squared. Columns : Possible treatment in the technique, using the same materials In the MEDA area, most countries build pillars with rough stone. They all insist on the need for selecting the stones with most regular possible courses and faces in order to obtain a homogeneous masonry, not requiring too much mortar and resistant to compression. The pillars are square, rectangular or cylindrical, always in solid stone, sometimes with alternate brick beds. In Lebanon, rough stone pillars laid in mortar were not reported.

Windows and Openings

Lintels and Arches: In the MEDA area, in rough stone constructions , one finds several types of lintel: • simple: single rough or squared piece of wood, branches or trunk sections cut into two

juxtaposed lengths, monolith stone going from a simple flat stone for small openings, to stone carefully cut, sometimes even profiled or carved. It crosses the width of the opening and rests on the jambs;

• in separate elements: arch installed on stone or bricks. The lintel can be surmounted by a relief arch (exceptionally as a frame) most frequently made up of several stone elements, less often out of fired or mud bricks, (in Cyprus for example) which defers the heaviest loads onto the jambs. Practically speaking, each country uses three solutions: a one part lintel (stone or wooden), with or without relief arch, an arch in separate elements, curved or flat. In rural environment, the wooden lintel is dominating. It can be in ash tree, in palm tree (because of its fibrous texture and its low resistance, its span is however limited to + / - 2 m), in cedar. In Lebanon, the lintels associated with this masonry are wooden or stone, with or without relief arch. Stone lintels can be slabs of monolithic stone, with or without relief arch, or an arch with separate elements. The wooden lintels are made either of a beam, or of a series of logs (with or without bark) generally mulberry tree. They are sometimes relieved by a flat stone arch laid on their base.

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Angle treatment in stone

Associated works : stairs, opening…

Windows and openings: lintel with support arch



ASSOCIATED WORKS (CONTINUED)

Windows and Openings (continued)

Jambs In the MEDA area, the jambs are often assembled in the course of the wall, with the same material and the same technique. The stones used can however be greater in dimension and of more regular shape. Some countries build the jambs in one or more elements, in squared or cut stone, sometimes profiled or carved. In this case, they generally support a monolith stone or wooden lintel. Brick jambs are described and illustrated by Morocco and Tunisia. Greece and Turkey specify that when a horizontal wooden anchoring is used, the jambs consist of two squared parts of wood connected perpendicular to the longitudinal anchoring elements, which act as lintel and threshold for the lower parts. In Lebanon, either in the course of the wall, or made of squared stones elements. Supports In the MEDA area, non-protruding supports are most commonly observed. The protruding supports are rarer. A few specifications on the materials used: wooden boards or squared pieces, sometimes profiled ashlar with mouldings. In Lebanon: protruding or non-protruding, in stone or wood. Dimensions In the MEDA area, the opening of the openings is generally in the form of a vertical rectangle. Multiple arch openings, semicircular arch shape, heightened, polyformed, enrich the composition of the external and interior façades (mainly in Morocco, in Tunisia, in Algeria and in the south of Spain). The dimensions of these openings vary in width from 10 cm minimum to 2,50 m maximum sometimes even exceptionally 3 m, and in height, from 30 cm to 2,50 m maximum. Small openings acting as a system of ventilation are sometimes made so as to obtain a decorative effect in the masonry (in Algeria, for example). In Lebanon, dimensions of the openings in rough stone wall are between 60 cm and 1, 20 m. in width and height; the common dimension of a window is 60 cm in width and 1, 20 m in height.

Associated Elements

In the MEDA area, Algeria, Morocco, Tunisia and Turkey describe corbelling volumes fixed on the façades. Later added balconies, galleries on the 1st floor of dwellings, protruding trunks, acting as floor or roof supports, waterspouts in palm tree through acroters, are the main associated elements mentioned by the partner countries. In Lebanon, for rough stone constructions, besides trunk supports for the roof, no associated element was reported.

Wall - roof Connections

In the MEDA area, generally speaking, when the roof is sloped, the runoff rough stone walls are protected by variable overhang length from the roof (rafters, wooden boards supporting the roofing material ). Almost everywhere, one announces flat stones, stones or fired bricks laid in corbelling on the head of the walls. For flat roofs, either the wall is prolonged by an more or less high acroter, open or not, thus enclosing the flat roof, or the protection rendering overhangs over the higher part of the external walls, or a system is built, making it possible to project rainwater further from the walls (branches in Morocco, for example). In Lebanon, for flat roofs associated to this type of construction, trunk roof support, with or without rows of flat stones or acroter to enclose the terrace.

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Wall - roof connection: examples

Evolution, transformation


This project is financed by the MEDA programme of the European Union. The opinions expressed in the present document do not necessari ly reflect the position of the European Union or of its member States. 9/9

USE, EVOLUTION AND TRANSFORMATION

Use

Types of building: In the MEDA area, the technique of stone laid in mortar, with or without horizontal wooden or brick anchoring is used everywhere mainly for apartment buildings and their annexes but also for public or religious buildings. In Lebanon, the rough stone wall technique is retained for rural dwellings and their appendices (cattle sheds, barns...). Period when the technique first appeared. Period when the technique is in use – still used today or disappeared : In the MEDA area, the technique of rough stone goes back to the dawn of times everywhere. Its use is disappearing, when it hasn’t already completely disappeared in some countries. Nevertheless, the traditional technique is still used in certain countries, in rural environment exclusively and generally for the restoration of old buildings. In Lebanon, the rough stone wall technique has been reported going back as far as the Bronze Age. Reasons why the technique disappeared or has been modified : In the MEDA area, the reasons evoked for the disappearing of the technique of rough stone are most frequently: • appearance of new materials considered as more powerful on the level of their implementation; • a high cost of skilled little requested labour, rarefies this process, and leads to the disappearing of know-how, from the construction technique

point of view as well as from that of maintenance. The horizontal wooden or brick anchorings are replaced by reinforced concrete frames. In Lebanon, the reasons for the disappearing of the rough stone wall technique are those commonly mentioned by partner countries.

Evolut ion / Transformation

Materials: In the construction business, rough stones are replaced by industrial materials, breeze 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 Lebanon, rough limestone is still used today, but only for facing. The traditional mortar with lime, earth, gravel and broken tile is replaced by a mixture of cement, gravel and sand. 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 rough stone constructions with mortar are now replaced by 20 cm concrete block masonries, with a 5 cm external rough stone facing, and /or covered with a rendering, about 2 cm thick. Evaluating materials and replacement techniques: -The 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 construction in stone is considered more satisfactory economically than aesthetically. There are worse problems with water and moisture and they do not provide good thermal and acoustic performance.

building a3 – rough stone wall with mortar · a3 lebanon – rough stone wall with mortar this...

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