MAJOR CAUSES OF DEFECTS IN BUILDINGS

The major causes of defects in buildings is as a result of ignorant of the following defects which leads to deterioration of the building. The defects are ;

1. Fungus stain and harmful growth
   Fungal stains or mould occur when there is moisture content in the walls. It flourishes in an environment of high humidity with lack of ventilation. Harmful growth includes creeping and ivy plants that can grow either on walls, roofs or gutters. This usually happens when dirt penetrate small openings in the walls and mortar joints, creating suitable grounds for seeds to grow. Roots can go deep into the existing holes causing further cracks and water penetration.

2. Erosion of Mortar Joints
   The main function of a mortar joint is to even out the irregularities of individual blocks either stones or bricks. Causes of mortar joint erosion include salt crystallization, scouring action of winds, the disintegrating effects of wall-growing plant, and water penetration resulting in dampness. Decayed mortar can be forcibly removed with a mechanical disc or manually raked out using a knife or spike.

3. Peeling Paint
   Peeling paint usually occurs on building facades, mainly on plastered walls, columns and other areas that are exposed to excessive rain and dampness. Some buildings located near the sea may face a greater risk. The amount of constant wind, rain and sun received can easily turn the surfaces of the paint to become chalky and wrinkled or blistered. As is the case in many heritage buildings, several layers of paints have been applied onto the plastered walls over the decades. Apart from lime wash, other types of paints used include emulsion, oil-based, tar, bituminous and oil-bound water paint. Different types of paints require different methods of removal depending on their nature.

4. Defective Plastered Renderings
   Defective plastered rendering occurs mostly on the external walls, columns and ceiling. In a humid tropical climate like Malaysia, defective renderings are normally caused by biological attacks arising from penetrating rain, evaporation, condensation, air pollution, dehydration and thermal stress. Other causes may be the mould or harmful growth, insects, animals and traffic vibration. Prior to being decomposed and broken apart, renderings may crack due to either shrinkage or movement in the substrate.

5. Cracking of Walls and Leaning Walls
   External walls may be harmful to a building if they are structurally unsound. Vertical or diagonal cracks in the wall are common symptoms of structural instability. Such defects should be investigated promptly and the causes diagnosed: be it the foundations, weak materials and joints; or any shrinkage or thermal movements such as those of timber window frames. Diagonal cracks, usually widest at the foundations and may terminate at the corner of a building, often occur when shallow foundations are laid on shrinkable sub-soil which is drier than normal or when there is a physical uplifting action of a large tree’s main roots close to the walls. Common causes of leaning walls include a spreading roof which forces the weight of a roof down towards the walls, sagging due to soil movement, weak foundations due to the presence of dampness, shrinkable clay soil or decayed building materials; and disturbance of nearby mature trees with roots expanding to the local settlement.

6. Defective Rainwater Goods
   Problems associated with the defective rainwater goods include sagging or missing eaves, gutters, corroded or broken downpipes, and leaking rainwater heads. Other problems include undersized gutters or downpipes which cause an overflow of water during heavy rain, and improper disposal of water at ground level. Due to inadequate painting, iron rainwater goods can rust and fracture. Lack of proper wall fixings, particularly by projecting lead ears or lugs can cause instability to the downpipes. If routine building inspections and maintenance have been neglected, rainwater goods can be easily exposed to all sorts of defects.

7. Decayed Floorboards
   Widely used in many heritage buildings including churches, schools, residences and railway stations, some timber floorboards have been subjected to surface abuses and subsequently deteriorated: leading to structural and public safety problems. The main causes are pest attacks, careless lifting of weakened boards by occupants, electricians or plumbers; lack of natural preservatives ; and corroded nails.

8. Insect or Termite Attacks
   Timber can deteriorate easily if left exposed to water penetration, high moisture content and loading beyond its capacity. Insect or termite attacks pose a threat to damp and digestible timber found in wall plates, the feet of rafters, bearing ends of beams and trusses, as well as in timbers which are placed against or built into damp walling. It is unwise to ignore timber that is lined with insect or termite holes because they may in time soften the timber and form further cracks. Affected timber can be treated by pressure-spraying with insecticide or fumigant insecticidal processes.

9. Roof Defects
   As roof often acts as a weather shield, it is important to treat aging roof tiles. In Malaysia, clay roof tiles have been widely used in the heritage buildings. Common defects of roof tiles include corrosion of nails that fix the tiles to battens and rafters, the decay of battens, and the cracking of tiles caused by harmful growth. Harmful growth poses a danger to the tiles because it may lift tiles and create leaks. Another aspect to be considered is the mortar applied for ridge tiles which tends to decay or flake off over the years.

10. Dampness Penetration Through Walls
    Dampness penetration through walls can be a serious matter, particularly to buildings located near water sources. Not only does it deteriorate building structures but also damages to furnishings. The main cause of dampness is water entering a building through different routes. Water penetration occurs commonly through walls exposed to prevailing wet wind or rain. With the existence of gravity, water may penetrate through capillaries or cracks between mortar joints, and bricks or blocks before building up trap moisture behind hard renders. Water may also drive further up the wall to emerge at a higher level. Dampness also occurs in walls due to other factors such as leaking gutters or downpipes, 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.

11. Unstable Foundations
    Foundations are a critical in distributing loads from roofs, walls and floors onto the earth below. They are structurally important to the permanence of a building and should this be lacking, it is pointless investing on superficial restoration work. Most of the common problems associated with the foundations depend on the geology of the ground upon which a building stands, structural failures as well as presence and height of a water table. Additionally, inherent failures may also happen in a building in which has to cope and carry any unsettled problem of the foundations. Problems of the foundations may lead to an unstable building structure, which is unsafe to users and occupants. Unstable foundations may occur because of several reasons including shrinking clay soil, penetration of dampness and water that may decay walls and foundations; presence of large trees near the building; and the undertaking of excavations nearby. They may also occur due to traffic vibrations, deteriorating of building materials and the increased loads, particularly with a change in building function.