A1 – Hewn stone wall (ashlar)

Building
techniques
A1 – Hewn stone wall (ashlar)
Country :
Lebanon
PRÉSENTATION
Geographical Influence
Definition
Hewn stone wall
- Traditional masonry tools:
and hammers.
chisels, picks
- 4, 5, 6 faces-sometimes 2 faces
- Stone laying with or without wedging.
- Stones are laid straight, regular size or not.
- Mortar laying.
Environment
In the MEDA area, ashlar is used in all environments: urban, rural, mountain, plain and sea side. It is often regarded as a noble technique,
through its fine workmanship and qualities, regarded as more urban than rural. Its is generally common.
In Lebanon, ashlar (Hajar Manhout) is found in all geographical areas, in rural and urban environments.
Illustrations
General view : Ville de Zahlé
Detail 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.
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A1 Lebanon – Hewn 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 aboveground, 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, the foundation is either directly on rocky ground, or a coarse, rough limestone,
header binder masonry, slightly broader than the thickness of the wall. Dimensions vary
between 50 and 90 cm thick for a wall between 30 and 60 thick. Binding is carried out with
lime mortar.
Building Materials
Type and hardness :
To build ashlar 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 = 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, the stone often used for ashlar constructions is limestone (reported hardness: 4
to 7). Hardness depends on the nature of the limestone used (pure lime, marly lime, sandy
lime).
c
Modules
Modules of all sizes can be found. Thus, throughout the Mediterranean area, blocks are 12 to
80 centimetres long, 8 to 40 cm high and 15 to 60 cm deep. Blocks may vary substantially in
volume from 2 litres to 100 litres. These blocks can non-the-less be handled by a few men.
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 ashlar are: in length, between 30 and 60cm, course height
between 20 and 40cm and depth between 20 and 40cm.
c
Construction principle: one facing wall,
general and detail view of construction
Construction principle:
materials and type of laying.
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.
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A1 Lebanon – Hewn stone wall
CONSTRUCTION PRINCIPLE (CONTINUED)
Mortar laying
Illustrations
Realisation / Construction:
Ashlar 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, ashlar masonries are laid in lime mortar.
Binding materials :
The two binders used for the realisation of ashlar masonry throughout the studied countries
are either lime, or earth.
In Lebanon, the binding material used for ashlar mortar is lime.
Aggregate :
The aggregates are sand, gravel, broken tile and coarsely or finely chopped straw.
In Lebanon, the aggregates used for ashlar stone mortar are sand, earth and gravel.
Aggregate-grading :
The grading of these aggregates varies according to their nature, from 0-3 mm to 0-6 mm,
and up to 12 mm in Israel and Jordan.
In Lebanon, according to the nature of the aggregates, the grading varies from 0-3 to 0-6 mm.
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.
In Lebanon, the reported dose ratio for ashlar mortar is of one volume of binding material for 3
volumes of aggregates.
Tools : Chahouta
Tools : Chahouta tool mark
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.
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A1 Lebanon – Hewn stone wall
CONSTRUCTION PRINCIPLE (CONTINUED)
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 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 thickness of ashlar walls varies from 30 cm for one linked facing walls (Moussafat) and between 60 and 120 cm for double linked
facing walls (Kalline). The latter are constituted of two linked walls with header binder stones, with an intermediate filling of stones and lime
mortar: the maximum height of theses walls reaches 4 to 5m.
Finishing
Four solutions for the finishing: bare wall, wall simply whitewashed, wall entirely rendered and wall rendered and whitewashed. Besides Portugal,
all the countries indicate that ashlar masonry - homogeneous and regular - remains generally apparent, at least outside. 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 facing leads to
leaving the wall bare, painting or rendering it. 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.
In Lebanon, ashlar walls are generally left bare, pointed, exceptionally rendered or whitewashed with lime. The interior walls are generally
rendered or whitewashed with lime.
Tools
In addition to traditional mason tools (wheel barrow , trowels, brush, plumb line, chisels, float, drift pins etc.), the traditional tools of the stone cutter
are necessary to prepare the stones. Besides, lifting tools (lewis, stone lifting bolts, pulley blocks, grips, levers...), wedges and thick glue are
needed.
In Lebanon, the traditional tools for cutting and sizing ashlar are: a set of hammers, chisel, " chaqoufé ", " dabboura ", " chahouta ", " pic ", "
tartabic ", still used in the construction of ashlar walls. The use of a granulating hammer is very common to texture the stone. The lifting methods
remain hand manned for constructions of this kind.
Trades
In each country, masons can build this type of wall. However, this technique is a stone cutter speciality, who can make up to 6 faces. Sometimes,
a first man cuts the blocks in the quarry and then mason carries out the laying.
In Lebanon, the realisation of ashlar walls is entrusted mainly to the mason, helped by a stone cutter and a carpenter (formwork, formwork
supports...)
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.
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A1 Lebanon – Hewn stone wall
CONSTRUCTION PRINCIPLE (CONTINUED)
Thermal and Acoustic Performance
For ashlar 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, ashlar constructions are considered good from a thermal and acoustic performances point of view. Limestone is clear coloured and
reflects sunrays. The thickness of the masonry as well as the external and interior renderings protects from heat in summer and retains heat in
winter.
Ageing Pathology
Linked to materials and climatic conditions:
For ashlar construction, 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 ashlar 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 ashlar constructions are those commonly reported by partner countries. They are also related to
the quality of the aggregates and materials used, more or less soft limestone; to the quality of the mortars and pointing, and to the layers of
protection (wash and/or rendering) as well as maintenance.
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.
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A1 Lebanon – Hewn stone wall
CONSTRUCTION PRINCIPLE (CONTINUED)
REALISATION DESCRIPTION
In Lebanon : (Text in French)
La construction en pierre hourdée taillée dressée 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.
Les moellons calcaires sont extraits de la carrière et amenés sur le chantier.
Le maçon marque alors au sol l'emplacement des murs.
Les ouvriers creusent ensuite les tranchées de fondation en rigole jusqu'à 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, le maçon détermine les angles de la construction et l'emplacement des ouvertures.
Le travail d'élévation du mur est systématique.
Le maçon fixe le niveau et positionne les moellons dans le mortier de chaux.
L’assistant apporte les pierres adéquates et le mortier au maçon.
Une vérification continue est réalisée horizontalement par un cordeau et verticalement au fil de plomb a fur et a mesure de la construction.
Les tailleurs de pierre préparent les pierres en fonction des besoins. L’un se charge des pièces particulières, l’autre réalise les modules de base
pour le mur. Un temps de pose doit être observé au bout de 4 assises consécutives réalisées le même jour. Pour les murs à deux parements, des
éléments en boutisses assurent le chaînage entre les deux parements.
Les angles peuvent être formés par une alternation de pierres longues et de pierres courtes, un harpage en relief est souvent réalisé et l’effet est
souligné par une bichromie des pierres ou un biseautage des pierres d ‘angle.
Le coffrage du mur ou des arcs dans celui-ci est réalisé par le charpentier, qui travaille essentiellement sur le site.
Les montages des éléments des jambages des ouvertures sont réalisés dans le cours du mur. Leurs pierres sont généralement choisies d’une
dureté supérieure au reste du mur, elles sont souvent taillées n’étant pas destinées à être recouverte d’enduit.
Le temps d’attente pour le séchage correspond à deux jours.
Les joints sont rejointoyés au mortier de chaux après l’édification, puis le mur est enduit et badigeonné à l’intérieur.
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.
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A1 Lebanon – Hewn stone wall
ASSOCIATED WORKS
A n g l e s a n d C o l u m ns
Angles:
Possible processing in the technique, by using same
Illustrations
materials
Generally, no specific processing of the angles was reported for ashlar 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 Lebanon, the angles of ashlar constructions can be carried out using the same technique
as the course of the wall. Angles are distinguished by a different processing of the surface: a
relief harping, protruding approximately 4 cm from the bare façade; a change of texture, stone
type or colour. In urban environment, ground floor angle walls are frequently chamfered at
45° or rounded to ease circulation in very narrow lanes.
Colunms: Possible processing in the technique, using the same materials
Ashlar 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 ashlar 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.
Associated works :
Angle and opening treatments
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.
In Lebanon, lintels are made with stone, single piece or separate elements, with or without
relief arch.
Finishing aspect : curving marks
Angle treatment
Lintels
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.
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A1 Lebanon – Hewn 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 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 common. Several countries reported and detailed
illustrations of protruding supports.
In Lebanon, in ashlar constructions, the supports are generally protruding, and sometimes
nonprotruding.
Dimensions
The technique of ashlar construction does not impose any specific 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 ashlar constructions, the dimensions of openings vary from 60 to 120 cm in
width and from 60 to 200 cm in height for walls with one-linked facings, (the standard is 80 cm
wide for 160 cm high).
For two linked facings (most common), the dimensions of openings vary from 60 to 180 cm in
width and from 80 to 200 cm in height, the standard is then 80 cm wide for 180 cm high.
Double or triple arch windows were also reported: they are typical and characteristic of
middle-class housing in the area.
All kinds of arcades can reach 3m height and width. Bull’s eyes (moubawaqat or qammarat),
are very common in this kind of wall, usually small in diameter (between 30 and 40cm).
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, small loggias are fixed onto the façades, "moucharabiehs", gemelled windows
with " mandalouns ". Arcades with stone flower tubs, balconies, stone corbelling stairs and
staircase sections, are all specific elements associated to ashlar construction openings.
Wall-r o o f C o n n e c t i o n s
In the MEDA area, when the roofs are 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 ashlar walls, stone cornices, profiled or not, have very often been reported.
Associated elements: acroter, ornamented
arch, mandaloun, ,loggia, stairs
Wall – roof connections
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.
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A1 Lebanon – Hewn stone wall
USE, EVOLUTION AND TRANSFORMATION
Use
Types of building:
The ashlar wall is especially used for commissioned architecture, religious buildings, military structures, noble and middle-class houses, or private
mansions. According to areas, the availability and the hardness of local stone makes this technique practical for apartment buildings and
annexes.
In Lebanon, the ashlar wall technique is used for all types of buildings.
Period when the technique first appeared. Period when the technique is in use – still used today or disappeared :
This technique has been used since Antiquity, during which it disseminated widely. It is still used nowadays, particularly for the rehabilitation of
certain historical buildings.
In Lebanon, the ashlar wall technique has been used since Antiquity. It was largely used until the middle of the 20th century (1940). Its use in the
original shape has disappeared today, but ashlar stone is still used for façades, in the form of stone plating.
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 knowhow, 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 all partner countries, particularly: high cost,
emergence of new materials and technologies, faster to implement and a disappearing of know-how.
Evolution / Transformation
Materials:
To a certain extent, far from the original technique, ashlar is being replaced with the cast agglomerate blocks (cement blocks, air concrete,
terracotta) on wide trade-networks. These blocks are identical in terms of module, but undergo a specific process for the angle, lintels and other
elements. They are assembled with a variable width, including reinforced concrete hardeners. In certain cases, particularly in the Middle-East,
stone plating imitates the aspect of the traditional technique.
In Lebanon, limestone is still used today, but for facing only. It is cut directly and by machine at the quarry, or recovered from demolition sites.
The traditional mortar, a mixture of lime, earth, gravel and broken tile, is now replaced by a mixture of cement, gravel and sand. The hydraulic
lime powder is common on the market. However air lime in rock or paste form (fat lime) can only be obtained upon request.
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.
In Lebanon, limestone is used in 2 ways: first for the construction of a single facing wall: the outside stone facing is dressed whereas the interior
facing receives a concrete layering; secondly, as stone plating. In this case it is machine cut, directly at the quarry, at following dimensions:
average thickness 8 cm and course height about 20 to 30 cm. Powder hydraulic lime is common on the market. The use of lime mortar is
reserved for the restoration work of historic buildings. Today, moulded stones have been reported to replace stone facings in heritage
construction areas.
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 ashlar constructions is considered satisfactory, aesthetically and economically but suffers
from water and moisture pathologies, and provides lower thermal and acoustic performance.
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.
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