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Why buildings decay
by Dr. A. Ghafar Ahmad
Paper presented at the E & O Hotel, Penang on December 11, 1994
(Organised by the Penang Heritage Trust)
Introduction
The term conservation has become familiar to almost everybody. From newspapers
to television, from small meetings to international conferences, people often
raise issues of conservation in regard to wildlife, rain forest or even historic
buildings. Conservation by definition is guardianship providing for maintenance,
preservation or protection of what presently exists, from being destroyed
or changed in an inappropriate manner. For wildlife conservation, it implies
a protection of endangered animals and plants collectively from being harmed
and killed either by people directly or by indirect human activity. In nature,
there is the implication of maintaining an ecological balance in steady state.
Similarly, conservation of building requires preservation and maintenance
of buildings of the past, which have historical and architectural significance.
It is a process which leads to the prolongation of the life of cultural property
and for its utilization now and in the future.
Building conservation has long been of concern, although its popular applications
is relatively recent in origin. In Malaysia, the practice of building conservation
is considered new in the local architectural scene. In the past few years,
many historic buildings have been preserved and conserved while others have
been converted to become premises for a bank, restaurant, information centre
or a printing office.
Before practising building conservation, one including an architect, building
contractor, planner or anyone who has the interest in saving an historic building
must have a broad understanding of the field itself. This is of course to
ensure that any action carried out during the conservation work is properly
performed and is in accord not only with the building requirements but is
within the scope of contemporary knowledge of the subject. The main purpose
of this paper is to study the common problems of historic buildings in Malaysia
and proportion of building conditions. This includes a discussion on building
materials and their common problems or defects mainly of timber, stone, brick
and plaster.
Present Situation of Building Conservation in Malaysia
Before going to the technical aspects of building conservation, the present
situation of building conservation in this country should first be highlighted.
As we already know, Malaysia is one of the fortunate countries that has many
historic buildings which are of immense architectural and historical values.
It is believed that there are more than 37,000 historic buildings built between
1800 and 1948 throughout the country which are worthy for preservation and
conservation.
Like many other countries in which building conservation seems a fairly new
practice, Malaysia faces several problems in dealing with the issues of historic
buildings. First, the present legislation on historic buildings is not sufficient
and suitable to protect such buildings from being demolished and destroyed.
There are presently four Acts and Enactments which show some aspects of building
conservation even though it is felt that their application and formulation
are restricted and not intended to address the question of heritage conservation
extensively. With the country's current rapid development in which the practice
of demolishing historic buildings has been the norm, none of these pieces
of legislation is comprehensive enough. Second, there is no suitable systems
for discovering and recording the historic buildings in the country. The systems
are quite important in building conservation, particularly among other things
to locate the building location, function and owner; classify the buildings
into their functions, assist the authority in keeping a record on the buildings
for future research and funding; and measure building defects and assess remedial
measures. Finally, there is lack of technical knowledge in repairing and maintaining
historic buildings. This is a major problem because almost all conservation
jobs involve both repair and maintenance stages requiring an understanding
of and analysis of building defect diagnoses.
In Malaysia, under the Antiquities Act 1976 a historic building or monument
aged at least 100 years old can be listed or gazetted by the Government through
the Museum Department to give protection and encouragement for preservation
and conservation. At present, there are 51 buildings and 86 monuments which
have been gazetted. Out of these 51 gazetted buildings, only 21 buildings
are British colonial architecture. Most of them are owned by the government
even though there are many privately owned buildings which are of architectural
and historical values. Example of historic buildings in Malaysia are traditional
Malay houses, mosques, churches, palaces, clock towers, prisons, government
offices, institutional and commercial, residential, schools, railway stations,
hotels and guest houses; and monuments.
Buildings Materials and Their Common Defects
Most of the historic buildings in Malaysia use building materials which are
easily available locally. Such building materials include timber, stone, brick
and plaster. In the care and conservation of historic buildings, understanding
the nature of the building materials and accurate diagnosis of defects is
most important. This is because historic buildings are, like older people,
vulnerable to all sorts of diseases. Therefore, in order to tackle the diseases,
conservation architects, contractors, specialised engineers and those involved
in building conservation should first become familiar with the building materials
in common use before going deeper into the proper techniques of preservation.
Common building materials such as timber, stone, brick and plaster will be
discussed as well as the causes of decay in each of the materials.
Timber has long been used by man especially in building construction. It is
the most useful material available for wall, floor, roof and other structural
framing. All commercial timbers can be classified into softwoods (such as
Pine, Fir and Damar Minyak) and hardwoods (such as Chengal, Meranti and Kapur),
depending on the characteristics of their grains, weight and moisture content.
In general, timbers either of softwoods or hardwoods have a moisture content
of between 12 to 15 per cent. Normally, a well dried timber has a moisture
content of 12 per cent. If the moisture content of the wood exceeds above
20 per cent, fungal rots, insect infestation and termite attack will eventually
take place. This will further lead to structural failure. Therefore, before
timber is being used for building construction, it is important for the material
to be seasoned and preserved. The primary aim in seasoning timber (either
of air or kiln seasoning) is to render timber as stable as possible, for the
timber increases its strength properties as it dries. On the other hand, the
preservation of timber, usually by chemical processes either before manufacture
or after, concentrates on fungicidal preservation, flame-proof protection
and water-repellence application.
Like timber, stone has been used in building construction for thousands of
years. Due to its natural durability and strength, stone is used for structural
columns, exterior walls, staircases, window framing as well as roofing materials.
Stone comes in different types and properties ranging from the hard impervious
such as granite, slate, marble to the softer and pervious sandstone and limestone.
Although stones will last for many hundred years, its tendency of decay in
any kind of weather is possible. Such weathering occurs in three situations.
First, the attacks from soluble salts especially when it comes up from the
ground where there is no damp course, in locations near seas or from a heavily
polluted atmosphere. Second, trouble arising from the slow build-up of soot
deposits and dust, leading to possible onset of decay due to small vegetation
organisms. Third, the straight forward erosion by wind and rain. Stone will
become saturated when it is exposed excessively to driving rain. As a result,
its surfaces becomes marked and rough. Besides weathering, stone may also
decay through faulty materials and workmanship.
Another type of material used in buildings masonry is brick or burnt clay
block. Brickwork has been used in many historic buildings in Malaysia, particularly
the ones built during the British occupation. Some of the colonial buildings
have exposed brick walls and others are plastered and painted. Old bricks
are slightly different than modern bricks. The texture of modern bricks looks
closer and smoother, and the edges are straighter and sharper compared to
the old materials. Colour and size are also different. Brick may decay through
weathering process including sulphurous smoke caused by polluted atmosphere,
water penetration through small holes and openings of the brick as well as
mortar joints; and dampness in wall caused by no damp course in locations
near sea or river. Brick may deteriorate due to harmful vegetation and also
mould or fungal growth that accumulate in the brick surface. Brick can also
decay due to cracks caused by structural movements. Such structural movements
may come from building foundations when subsoil is compressed through the
decades or centuries followed by wall deflections due to the foundation weakness
or an uneven loading distribution from above wall structure.
Like timber, stone or brick; plaster tend to deteriorate over a period of
time. Plaster normally contains lime, sand and water; and sometimes chopped
animal hairs to give tensile strength. Plaster are used widely in decorative
panels, ceiling renderings, cornices and internal walls. Causes of deterioration
include direct exposure to driving rain, condensation, evaporation, air pollution,
aerosols, capillaries, thermal stresses, vegetal causes, insect attacks, animals
and human activities. Plaster may become cracked due to either shrinkage or
movement in the substrate. Shrinkage usually occurs early in the life of the
building but substrata movement is often the reason for failure in historic
situations.
Common Problems of Historic Buildings
I have carried out building surveys and inspections covering site investigations,
structural survey, building condition and defects, air-conditioning systems;
and photographic study on 70 selected colonial buildings built between 1800
and 1930 throughout Peninsular Malaysia. Each building was studied externally
and internally following permission from its occupants or owners. The buildings
are located in Penang, along the west coast, in central regions, a few areas
on the east coast and other remote places; representing a geographical cross-section
of colonial architecture throughout the Peninsular Malaysia. The main purpose
of the surveys and inspections is to study the common building defects or
problems and proportion of building conditions.
Of the 70 colonial buildings surveyed, 27 buildings were built between 1900
and 1920. Followed by 20 buildings built during 1880 and 1920, 11 between
1920 and 1930, 6 between 1860 and 1880, 3 during 1800 and 1820; and the other
3 between 1820 and 1860. From the survey, 18 buildings or 26% of the total
buildings were in good condition. However, the other 52 buildings or 74% shared
some common building defects or problems. It was found from the study that
sometimes one building shared 3 or more common building defects, depending
on its location, age, building materials and changes in use. There are 12
common building defects or problems, which are fungal stain or harmful growth,
peeling paint, defective plastered renderings, poor installation of air-conditioning
units, defective rainwater goods, decayed floorboards, cracking of walls,
erosion of mortar joints, dampness penetration through walls, roof defects,
insect or termite attack; and unstable foundation. The most common building
defects, found on 27 out of 52 buildings, is fungal stain or harmful growth
carrying 51.9%. Other common defects or problems include erosion of mortar
joints 38.4%, peeling paint 30.7%, defective plastered rendering 21.1%; and
poor installation of air-conditioning units 28.8%.
Causes to the Common Problems:
Fungal Stain / Harmful Growth
Fungal stain or mould usually occurs when there is a presence of water or
high moisture content in masonry walls. It can easily flourish in environmental
conditions of high humidity and lack of ventilation. Fungal stain can be seen
on wall surfaces of a bathroom, kitchen, near rainwater goods including down
pipes and gutters; and at washing areas.
Harmful growth including creeping and ivy plants can grow on either stone
or brick walls. This happens when dust and dirt penetrate small holes, openings
and cracks in the walls and mortar joints creating a suitable ground for any
seeds to grow. The condition becomes worse when there is water penetration
through the holes. Roots can go deep into the existing holes causing further
cracks and water penetration.
Erosion of Mortar Joints
Basically, the main function of a mortar joint is to even out irregularities
of individual blocks, whether they be of stones or bricks. At the same time
it provides some adhesion between the blocks. Causes to the erosion of mortar
joints include a presence of salt crystallization, scouring action of winds;
and disintegrating effects of plant growing on a wall or water penetration
leading to the concentrations of moisture and dampness. Decayed mortar can
be removed forcibly by the use of a mechanical disc or carefully raked out
by using a knife or spike manually.
Peeling Paint
Peeling paint usually occurs on building facades, mainly on plastered walls,
columns and other areas which are exposed to excessive rain and dampness.
Some buildings located near the sea may face a much greater risk once the
signs of peeling paint are visible on the exterior walls. This is because
the amount of constant wind, rain and sun received can easily turn the surfaces
of the paint to be chalky and wrinkled or blistered. In many historic buildings,
there are layers of paints being applied on plastered walls. Apart from lime
wash, there are many types of paints used on wall surfaces including emulsion,
oil-based, tar, bituminous and oil-bound water paint. All of these require
different methods of removing depending on the nature and conditions of the
paints.
Poor Installation of Air-Conditioning Units
Most of historic buildings in Malaysia were built without air-conditioning
systems. Where buildings have to contend with high humidity and warm temperatures,
the need to install air-conditioning systems to meet modern building requirements
seems necessary. Window units and openings are usually closed and sealed to
maintain cool air inside the buildings. Depending on the building function,
structures and the effects on building fabric; one should consider four main
aspects before deciding to install the air-conditioning units in any historic
buildings. Firstly, the cooler and drier air produced by the air-conditioning
systems may possibly cause shrinkage of building materials. Secondly, there
will be a possibility of condensation either on the surfaces or within the
structure of the fabric. This allows the build-up of mould or fungal stains.
Thirdly, there may be problems of installation which include difficulties
in installing the units. Finally, from the aesthetic point of view, the installations
of the air-conditioning systems in some historic buildings were unfortunately
carried out in a poor manner by simply placing the units on windows, walls
or at front facade. This affects the appearance of the buildings.
Defective Plastered Rendering
In many historic buildings, defective plastered rendering occurs mostly on
external walls, columns and ceiling. In a humid tropical climate, the defects
of rendering are normally caused by biological attacks arising out of penetrating
rain, evaporation, condensation, air pollution, dehydration and thermal stress.
Other causes may come from mould or harmful growth, insects, animals and traffic
vibration. Prior to being decomposed and broken apart, plastered rendering
may become cracked due to either shrinkage or movement in the substrate itself.
Cracking of Walls / Leaning Walls
Apart from distributing loads from roofs and floors to foundations, external
walls may be harmful to a building if they are structurally unsound. Cracks
in wall, either vertical or diagonal, are common symptoms of structural instability.
Such defects should be investigated and the cause diagnosed in either the
foundations, weak materials and joints; or any shrinkage or thermal movements
such as timber window frames. Diagonal cracks, which often being widest at
the foundations and may terminate at the corner of a building, often occur
when shallow foundations are laid on shrinkable sub-soil that is drier than
normal or when there is a physical uplifting action of main roots of a large
tree close to the walls. Furthermore, there are a few causes to the problem
of leaning walls including spreading roof which forces the weight of a roof
down towards the walls, hogging and sagging due to soil movement, weak foundations
due to presence of dampness, shrinkable clay soil or decayed building materials;
and disturbance of nearby mature trees in which their roots gradually expand
the local settlement.
Defective Rainwater Goods
Common problems associated with the defective rainwater goods include sagging
or missing eaves gutters, corroded or broken galvanized iron down pipes; or
leaking rainwater heads. Others may include undersized gutters or down pipes
which cause overflow of water, particularly in heavy rain; and an improper
disposal of water at ground level. There are a few possible causes to the
defective of rainwater goods. Due to inadequate painting, iron rainwater good
can become rusted and fractured. Lack of proper fixings of the wall, particularly
by means of projecting lead ears or lugs can cause instability to the down
pipes. Where the routines of building inspections and maintenance have been
neglected, the rainwater goods can be easily exposed to all sorts of defects.
Decayed Floorboards
Timber floorboards are widely used in many historic buildings including churches,
schools, residential and railway stations in Malaysia. Some of the floorboards
are badly abused with serious damages on the surface and deteriorated; leading
to further structural problems and unsafety of occupants. The main causes
to the deterioration are insect and termite attacks, careless lifting of weakened
boards by occupants, electricians or plumbers; lack of natural seasoning and
preservatives, and corroded nails.
Insect or Termite Attacks
Timber has been widely used in many historic buildings in Malaysia. It can
deteriorate easily if it is exposed to water penetration, high moisture content
and loading beyond its capacity. Insect or termite attacks are a common danger
to timber. Insect or termite attacks usually happen in a damp and digestible
timber which can be found in elements such as wall plates, the feet of rafters
and bearing ends of beams and trusses; and in all timbers which are placed
against or built into damp walling. It is dangerous to leave the timber with
many insect or termite holes because they may soften the timber and form further
cracks. Affected timber can be treated by pressure-spraying with insecticide
or fumigant insecticidal processes.
Roof Defects
Besides being one of the main structures in a building, roof may act as a
weather shield, giving protection to users or occupants from rain and sun.
Therefore, it is important to treat any aging roof tiles. In Malaysia, clay
tiles have been widely used in the historic buildings. Common defects of roof
tiles include the corrosion of nails fixing the tiles to battens and rafters,
the decay of battens; cracking of tiles which may be caused by harmful growth
or walk upon. The harmful growth is quite dangerous to the tiles because it
may lift the tiles and create leaks. Another aspect to be considered in the
common defects is the mortar applied for ridge tiles which tends to decay
or flake off over the years.
Dampness Penetration Through Walls
Dampness penetration through walls can be a serious matter, particularly to
the buildings which are located close to water sources. It can cause not only
deterioration to the building structures but damages to furnishings and contents
as well. The main cause of dampness is water which may enter a building by
a number of different routes. Water penetration occurs commonly through walls
exposed to prevailing wet wind or rain. With the existence of gravity, water
is likely to penetrate through capillaries or cracks between mortar joints
and bricks or blocks before building up trap moisture behind hard renders
and also driving further up the wall to emerge at a higher level. Dampness
may also occur in walls because of other factors such as leaking gutters or
down pipes, defective drains, burst plumbing and condensation due to inadequate
ventilation. Dampness may also enter a building from the ground through cracks
or mortar joints in the foundation walls.
Unstable Foundations
Foundations are a part of a building which distributes loads from roofs, walls
and floors on to the earth below. They are structurally important to the permanence
of a building and if this is lacking there is no point of spending large sums
of money on other superficial restoration work. Most of the common problems
occurred in the foundations depend on the geology of the ground upon which
a building stands and is surrounded by, structural failures; and presence
and height of a water table.
Besides, inherent failures may also happen in a building
in which it has to cope and carry any unsettled problems of the foundations.
A famous example is the Leaning Tower of Pisa in Italy of which inherent failures
caused by corrections made during construction combined with traffic vibrations,
deep construction and abstraction of water from deeper layers of soil have
led to its present leaning position. It is important to understand that all
of the common problems of the foundations may lead to unstability of the building
structures, causing unsafety to users or occupants.
Unstable foundations may occur because of several reasons
including shrinking clay soil, resulting when the sub-soil is drying and water
table is low which no longer holds the structure above; penetration of dampness
and water that may decay walls and foundations; presence of large trees near
the building; and the undertaking of extensive excavations or mining nearby.
Other cause include landslides caused by heavy rain, heavy construction near
an historic building and lowering of water tables, usually by hard landscaping
and road areas. Unstable foundations may also occur from traffic vibrations,
deteriorating of building materials and the increased loads, particularly
when there are changes in building function.
Factors That Govern Building Defects or Problems:
There are 5 factors that govern building defects or problems.
Climatic Conditions
It is important to consider the climatic conditions of Malaysia and the effect
on building materials. Like many other tropical countries, Malaysia has heavy
rainfall and warm sunshine all year round. This implies that buildings in
the country tend to weather rapidly, particularly in respect to external building
materials which are exposed to external causes such as rain, wind, solar radiation
including ultra-violet light; and atmospheric pollution. Fungal stain, harmful
growth, peeling paint, erosion of mortar joints and defective plastered rendering
are a few examples associated with this factor.
Location of Building
Buildings that are located near the sea or rivers tend to have common building
defects. This is because the water coming from the ground causes dampness
penetration and structural instability. For example, during the conservation
work of the Sultan Abdul Samad Building in Kuala Lumpur, damp-proof courses
had to be installed in order to prevent rising water coming from nearby Gombak
River. In addition, soluble salt which comes from sea and together with the
presence of a polluted atmosphere can cause damage to the exterior surface
of the buildings.
Building Type and Change in Use
Most historic buildings that maintain their original functions or uses appear
to have less problem internally, even though there were symptoms of building
defects found on the external fabric. Buildings that change their use and
spaces should consider the effect of the new use on the existing structure.
This is because historic buildings were built to only hold certain loads and
sometimes may not withstand additional loads. Where buildings which have been
converted into either commercial or office purposes, the need to install air-conditioning
systems to meet modern building requirements seems necessary. It has been
found that in a few cases the air-conditioning units were placed improperly.
This not only affects the appearance of the buildings but intervenes with
the existing fabric, particularly when ducts are running in full view on the
ceiling.
Maintenance of Building
Building maintenance organized through a rigorous programme of cyclical maintenance
plays a major role in preventing building defects. Historic buildings that
neglect building maintenance may fall into several defects which may lead
to structural failures. Any inspections carried out by either architects or
surveyors should include checking for any signs of abnormal deterioration,
cleaning out gutters of leaves or harmful growth, checking lighting conductors,
cleaning out all voids and spaces; and changing tap washers. To secure the
general structural stability and life of a building, it is important to regularly
inspect not only the main structural elements including foundations, walls
and roofs; but other common building problems.
Building Age
All elements of historic buildings tend to deteriorate at a lesser or greater
rate depending upon their location and function. Aging building materials,
particularly timber should be checked once there are signs of fungal and termite
attacks. Building that were built in the early period of British occupation,
for instance, often face problems in building materials. Therefore, proper
treatment of building repair and maintenance should be given full consideration.
Conclusions
Identifying common building problems and understanding of building materials
explained in this presentation are considered as part of the process of preserving
and conserving historic buildings. Reasons for building conservation, adopting
proven techniques and treatments, maintaining the historical and architectural
values are a few examples of areas that one should have a knowledge of before
practising building conservation. As a conservation architect, engineer, surveyor,
historian, planner or anyone who has the interest in saving our architectural
heritage, we have to make sure that our historic buildings are handed to the
next generation in good conditions.
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