2chapter two
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CHAPTER TWO: LITERATURE REVIEW
2.1 Definition of Terms
2.1.1 Traditional Buildings:
A tradition could be described as a long established action or pattern of behaviour
in a community or group of people, often one that has been handed down from generation
to generation (Encarta dictionaries, 2007).
A traditional building, therefore, could be defined as any building that is related
to, or, designed based on traditional values, materials and methods of construction.
2.1.2 Conservation:
Conservation could be defined as the preservation, management, and care of
natural and cultural resources. It could also be defined as the keeping or protecting of
something from change, loss or damage.
2.1.3 Preservation:
Preservation, however, could be defined as the guiding of something from danger,
harm, or injury. Preservation could also be defined as the maintenance of something,
especially something of historic value in an unchanged condition.
Preservation particularly deals with cultural property. It entails protecting cultural
property by controlling its environment, thus preventing agents of decay and damage
from becoming active (Maddex, 1985).
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Preservation also includes control of internal humidity, temperature and light, as
well as measures to prevent fire, arson, theft and vandalism, and to provide for general
cleaning and prevention of decay, through timely repairs and intervention.
2.1.4 Museum:
From the Latin word ‘mouseoin’ meaning ‘place of the muses’; a museum is an
institution where objects of artistic, historical or scientific importance and value are kept,
studied and put on display.
2.2 Significance of Conservation
Old buildings convey an aura of the past to the present generation. They tend to
make us appreciate the beauty of the architecture and the technicalities of engineering
that existed before our time. However, these buildings will keep wearing away, as time
goes on, and with them the values that are cherished, unless there is some sort of
intervention, hence the importance of conservation.
Conservation of traditional and historic buildings helps, therefore, to retain and
protect them, so that future generations can learn about the history and construction
techniques associated with old buildings and structures (Pam, 2002) in Aliu (2006).
2.3 Significance and History of Museum Buildings
A museum building serves as a place for documentation, exhibition and education
for the present generation as regards what has happened in the past. However, for any
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meaningful plan or projection into the future, an adequate knowledge and understanding
of the past and present is required in a perfect synthesis if any success is to be achieved.
This is the role of the museum building in the society. Museum buildings do not
only serve as places where object of history and relics are kept, but also as tourist
avenues themselves excluding the relics that they contain.
The earliest museums, resembled today’s libraries and scholarly institutes and
were established as sources of inspiration and enlightenment. At his capital city of ‘Tal al
Amarinah in Egypt, Pharaoh Akhenaton (ruler from about 1353 to 1335 B.C) erected a
large library in which he stored the many gifts and tributes that allied rulers and subject
peoples had given him (Encarta encyclopedia, 2007).
The term ‘museum’ was first applied to a state-supported research in Alexandria,
Egypt, founded by king Ptolemy 1 early in the 3rd century B.C to foster scientific studies.
Also, religion, especially Christianity in the Middle Ages played a great role in the
development and growth of museums, as churches became the focal point for collecting
religious relics, jewels, precious metals etc.
Collections in the Islamic world and Asia however took the form of spoils of war.
Collections of art works by the nobility also played an important role in developing
museums as can be seen in palaces and temples of China and Japan e.g. Shosoin (Shoso
House) at Todai ji (Todai temple).
In West Africa, however, one of the most prominent museums is Nigeria’s
National Museum in Lagos, which has masks, ancient terracotta, figures and a top
collection of the famous bronze sculpture and ivory carvings produced by the Benin
kingdom, which flourished from the 15th to the 17th century (Encarta encyclopedia, 2007).
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2.4 Causes of Deterioration/Decay in Traditional Buildings
A building may be said to deteriorate when its quality, value and or strength
declines due to a number of reasons. This is a common trend with traditional buildings
nowadays, chiefly because they suffer neglect, as people prefer to use and reside in
modern buildings built of block, concrete or glass.
In conserving a building therefore, the aspect of its macro environment which has
a direct implication on the deterioration of the building must be treated with undaunted
commitment if success is to be attained.
On a general note, various factors contribute to the deterioration/decay of
traditional/ historic buildings. These include:
a. Climatic factors
b. Chemical factors
c. Biological factors
d. Engineering factors
e. Man-made factors
f. Construction materials and technique
Other factors (which particularly relate to earth buildings) can be said to include;
a) Structural-related factors
b) Water-related factors
c) Vegetation, animal and insect related factors; and
d) Material incompatibility
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2.4.1 Climatic Factors:
Climate, in all its aspects, is one of the fundamental causes of the decay of
buildings, through failure of their materials which in turn affects the structure (Fielden,
1994). All of these aspects all act on a buildings fabric and in the process cause it to wear
out with time.
2.4.1.1 Solar Radiation:
Solar radiation is the prime cause of climatic conditions (Fielden, 1994). It is
greatly responsible for a host of other climatic agents like rainfall clouds, humidity and
precipitation etc. It causes building surfaces to deteriorate after long-time exposure due to
its inherent harmful components of ultraviolet light, which is destructive to building
elements.
2.4.1.2 Temperature:
The cause of air temperature change is almost entirely the heating effect of the
sun by day through both short and long-wave radiation and convection at night.
Building materials are heated by solar radiation in three ways: by direct solar gain
from external radiation, by indirect internal solar gain through windows- the ‘green house
effect’ and by indirect heating via the external air whose ambient temperature is raised by
the sun. All building materials expand when heated and contract again when cooled, this
expansion and contraction is called thermal movement and is a major cause of
deterioration and decay, especially in traditional buildings that have stood for decades,
seeing both the sun and the rains.
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2.4.1.3 Moisture and precipitation:
The patterns of precipitation are important to understand relative humidity levels
and for developing strategies in moisture control.
The presence of water in any of its various forms causes or accelerates the decay
of most building materials (Fielden, 1994). Water reaches a surface when the rain hits the
surface directly; it may also reach the surface indirectly, falling somewhere else on the
building and gaining access through a more complicated path e.g. from the roof slope,
and passing underneath to the members and subsequently into the building interior. Water
can also gain access through capillary action.
2.4.1.4 Wind and air movement:
Wind is normally described as air in motion. Winds are produced by differences
in atmospheric pressure, which are primarily attributable to differences in temperature.
Variations in the distribution of pressure and temperature are caused largely by unequal
distribution of heat from the sun, together with differences in the thermal properties of
land and ocean surfaces (Encarta, 2007).
Wind speeds vary at different heights and cause turbulence. The building structure
must be strong enough to resist wind pressures; it must also be able to resist the
associated section on its lee side. Forces generated by wind can cause buildings such as
bell towers to sway. It is theoretically possible for wind pressure to cause tension in the
windward face of a tall, thin structure. Great wind speeds, on hitting the surface of
traditional buildings such as mud walls, could slowly lead to deterioration by tearing
away parts of laterite wherever it strikes.
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2.4.1.5 Rainfall:
Rainfall is a chief climatic agent, which can cause a lot of harm especially to mud
buildings. The presence of rain water causes or accelerates the decay of most building
materials (Aliu, 2006).
Rain can penetrate to the interior of a building and cause various kinds of decay
(Fielden, 1994). Absorbent surfaces such as brick and mud walls therefore offer very
little resistance to this agent of decay.
2.4.2 Chemical Factors:
Materials used in the construction of buildings relate chemically with one another
and with the surrounding environment. One of the considerations to be made in the
choice of building materials is the action of dissolved salts on them. Salts normally act on
building surfaces and materials through any of the following compositions;
a) The sulphates of sodium, potassium, magnesium and calcium which are
normally hazardous to wall rendering, causing materials to disintegrate by
weakening the cohesion between them.
b) The nitrates of sodium, potassium and calcium which result to
efflorescence and leads to decay and deterioration on contact with building
surfaces.
c) Sodium chloride does not disintegrate building components by itself but
could react with other salts and compounds on building surfaces which
could slowly lead to decay.
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2.4.3 Biological Factors:
On the macro and micro cellular level of life, various organisms interfere and at
the long run often lead to decay in the life of a building. Organisms like bacteria and
lichens cause the decay of building materials by producing acids which react chemically
with the structural material (Fielden, 1994).
Some micro organisms develop rapidly if the air has a relative humidity of over
65%, and they spread quickly if there is light. However some others like fungi, mildew,
moulds and yeast do not require sunlight for growth. They depend upon organic material
such as plant life for their energy.
Organic materials in building such as wood are vulnerable to insect attack. Insects
cause a great deal of damage to the building structure by weakening structural timbers or
rafters, and in many parts of the world they are a more likely threat to woodwork than
fungi.
Other insects liable to causing damage include carpenter bees, weevils, beetles,
termites etc. termites are dangerous and voracious and will attack wood fibres or keratin
materials and destroy almost anything; including synthetic material, that is not too hard,
repellant or toxic.
2.4.4 Engineering Factors:
This practically refers to the structural components and aspects of buildings. Poor
and improper use and choice of building materials, inaccuracy in assessment of loadings
and possible differential settlement affects the foundation and the structure as a whole.
Others are incorrect spacing of expansion gaps and inadequate supervision of
construction (Fielden 1994).
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2.4.5 Man-Made Factors:
These are factors contributing to the decay and dilapidation of traditional and
historic buildings which arises as a result of man’s actions. Man-made causes have
immense implications in the conservation of historic and traditional buildings.
Industrialization is one major human induced factor of building decay. Industrial
production, together with electricity generation, is the main cause of atmospheric
pollution as well as the heavy traffic that causes vibration damage.
Pollution, whether noise, sound etc produced from industries or generated from
moving vehicles are all manmade hazards which could contribute to the gradual decay of
a building.
2.4.6 Construction Materials and Techniques:
The nature of materials used in the construction of a building will go a long way
in determining how long the building may last.
Materials like stone are more durable than mud in terms of stability, water
absorption, thermal and sound insulation etc. Also the methodology employed in the
construction of these buildings and the level of accuracy so attained can be possible
potential threats to building durability and stability.
2.4.7 Structural-related factors:
These factors have crucial implications on the conservation maintenance of an
earth building like the Gidan Makama museum complex. Effects of improper design or
construction, foundation failure, building material failure etc. should be major
considerations in this context.
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Cracks (whether structural or due to shrinkage and swelling action), lead to
structural failure to a considerable degree; as well as beam deflection, misalignment of
beams, corbels, columns etc.
2.4.8 Water-related factors:
Water-related factors often lead to gradual deterioration of the building fabric.
The action of rising damp, minerals and salts, rain water, erosion, surface water, coving
and rain splash all contribute to deterioration of earth buildings.
Dimensional changes in moisture content of building materials also play a
significant role in building deterioration and decay. These range from shrinking and
swelling, freeze-thaw, to liquid-plastic limit changes.
2.4.9 Vegetation, animal and insect related factors:
The combined effects of vegetation, animal, and insects as natural factors have the
tendency of causing severe harm to the building envelope to the point of decay.
Plants existing around the building also grow on the same soil which
accommodates the building foundation. This means that the roots will compete with the
foundation for space. There are also moisture effects on building foundation, as plants
absorb underground water through their roots.
Animals will burrow into, and travel over walls. There is also the tendency of rat-
runs, insect nesting in walls action of masonry bees-all of which contribute in reducing
the structural integrity of mud (earth) walls.
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2.4.10 Material incompatibility:
When building materials are not properly married together, the very building
blocks of the structure could serve as agents of its decay. Materials used in combination
should be compatible and not be too different from one another, for instance materials
used should have similar co-efficients of expansion, absorption and contraction properties
etc.
2.5 Defects Arising from Deterioration and Decay
Defects naturally occur in a building’s structure when it starts deteriorating. Some
of the defects that can arise include the following:
2.5.1 Moisture Movement:
Moisture movement is the result of the expansion and contraction action due to
water absorption and drying out. The movement of moisture within the pores of building
materials can cause considerable amount of damage. When there is change in the
moisture content of building materials, deformation if very likely to occur.
Under normal circumstances, moisture gains access to walls around their base
through rising damp from the ground, precipitation and rainfall. Moisture movement in
structural systems of traditional buildings (usually of mud and bamboo) is very dangerous
as it may lead not only to the decay of the building but to complete collapse.
Where moisture particles attacks mud used on walls, it first weakens the wall
finish, thereby penetrating and loosening the wall structure itself.
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In structural bamboo, moisture presence makes it inviting for other agents of
dilapidation (e.g. termites) to attack and cause damage.
2.5.2 Cracks:
A crack can be described as an evident indication of compressive and tensile
action in walls. This compressive and tensile action, often results from induced stresses
arising from shrinkage restraints, chemical action such as corrosion of steel
reinforcements, thermal and moisture movement (Aliu, 2006).
2.5.3 Roof Defects:
A roof is one of the primary sheltering elements protecting the interior from
natural weather hazards (Abubakar, 2003). Some of the defects and problems associated
with roofs normally occur from poor structural design, poor quality of lightweight timber
(azara in this instance), alterations made after the initial construction such as cutting
through tie beams, loss of strength owing to aging of timber, breaking of joints, sagging
and spread due to rotting of ends of beams, rafter and wall plates or movement of
supporting masonry.
2.5.4 Vegetation and Landscape Effects:
Tree roots can extract large quantity of water from soil. A fully grown tree uses
over 50,000 litres in a year when the soil is of clay (Chiroma, 2002).
The roots of trees can cause blockages and local ground dampness by finding
their way into rain water drains. In extreme cases when rain water drains are broken by
roots, the leaking water can cause sandy types to wash away from below foundations.
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Conversely in clay soils there is the well-known fact that trees can damage
foundations by excessive withdrawal of ground moisture in summer, resulting in ground
shrinkage and foundation movement with subsequent cracking of the walls and partitions.
2.5.5 Effects of Foundation Movement:
Foundations are that part of the building which distributes the loads from roofs,
floors and walls unto the earth below (Fielden, 1994).
Ground water movement, such as rise in the water table level can cause harm to a
building’s foundation. The earth around the foundation begins to depreciate in its bearin g
capacity, and though this might cause slight foundation movement and settlement,
preventive measures should be taken to ensure that serious and harmful movements do
not occur.
Abstraction of ground water is also one of the principal reasons for ground
movements, causing the shrinkage of clay and peat soils. Mining subsidence is another
cause of such movements.
2.6 Remedies to Building Defects
2.6.1 Prevention of Unnecessary Moisture Attack
Unwanted and unnecessary moisture could be prevented from gaining access into
the building interior, especially through rising damp from underneath the ground and wall
penetration. This can be done normally by incorporating damp proof materials as well
and floor coating. Proper channeling of drainages could also hamper unnecessary
movement of ground water.
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2.6.2 Prevention and patching of Cracks:
Some cracks are uncalled for in walls and can be prevented in design stage e.g.
through the prevention of unnecessary loading conditions. Local settlements also cause
slight cracks in buildings and can be prevented for instance by checking the foundation
soil and ensuring that it is free from roots of old trees, a midden or hog-hole or well.
Cracks in walls could be patched using mortar (to which makuba is normally
added). The mortar would be mixed in such a way as to attain the highest plasticity
required to effectively seal the crack.
2.6.3 Proper use of roof materials and drainage:
Roof defects could be prevented from the design and construction stage; by the
specification and use of proper roofing materials for instance high quality azara be used,
which would resist the combined stresses.
A number of roof defects also arise from improper or inadequate roof drainage
resulting in moisture penetration; this gradually results to building decay. This problem
can be simply countered by properly draining the roof systems, and paying particular
attention to roof drainage detailing.
2.6.4 Controlling the effect of vegetation and landscape:
Deep rooted trees are problematic to the foundations of surrounding
developments. Therefore, planting shallow rooted trees, well spaced away from the
building envelope would be an effective counter-measure.
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2.6.5 Prevention of excessive foundation movement:
Doing away with deep-rooted trees as discussed above will also be an important
remedy in preventing unnecessary foundation movement.
Shrubs and grasses could be used to prevent the effect of surface erosion which
could be a major cause of foundation movement.
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