Introduction
Building defects are always under the spotlight and the grave concern of the construction industry. Different complexes or buildings produce different kinds of defects and require numerous levels and types of quality, which count on the building functions, the structure or maintenance systems and also materials used.
According to Watt (1999), "a defect may be considered to be always a failing or shortcoming in the function, performance, statutory or user requirements of the building and it might manifest itself within the composition, cloth, services or other facilities of the afflicted building. "
Josephson and Hammarlund (1998) quoted from Svensk Standard, SS 020104 (1987) says that defect is thought as 'the non-fulfilment of planned usage requirements' in which requirements are determined by law, laws, building specifications as well as in deal documents, site meeting data and other task documentation. However, not all requirements can be specified as there are many details that are difficult to designate such as non-expressed basic needs of every individual. Therefore, these demands are referred as 'consumption' requirements. Opinions and replies from project participants are needed whenever specified requirements are wrong and defects will likely appear if those views are not complied.
There is a difference between failing and defects. Failure is defined as deviation from original technical specs which can or can't be corrected before the handing over of the building. On the other hand, defect is termed as scarcity of the performance which becomes obvious once the building is functional. Failing to differentiate both terms may lead to inaccurate and imperfect measurements, cost determination and perhaps inappropriate methods to reduce its occurrence (Atkinson, 1987).
Georgiou et al (1999) claim that defects can be categorized as major defect or small defect. Major defect is considered as those which cause the building to become unsafe, unsuitable for living in and not suitable to be used for the purposes that the building was designed. On the other hand, minor defects is recognized as those originate from poor craftsmanship or deficient materials found in the structure of the building but do not cause the building to become unsafe, unsuitable for surviving in and not ideal to be used for the purposes that the building was designed. Defects which require significantly less than Australian $500 to repair are believed as minor defects. For the time being, major defects are defects are present after twelve months which need more than Australian $500 to correct and the majority of them are structural deficiencies (Georgiou et al, 1999).
Georgiou (2010) and, Andi and Minato (2003) state that defects happen if a component has a shortcoming and will not comply its designed functions and suitable level of quality as required by owners, contractors or polices.
Causes of defects
Some of the defects are induced by natural implications that developed above the time period such as aging and typical uses. However, many premature defects appear because of the fact that poor skills and attention are designated on the building. The analysis because they build Research Establishment concludes that over 90 % of the building defects are induced by the quickly diagnosable faults in design or structure that could be foreseen beforehand and prevented.
Generally the causes of defects are mentioned as the followings: (Lee, 1987)
Insufficient brief
Defects tend to be interpreted as originated from the strokes of creator or on the drawing panel in most cases but in some cases they can be attributed as occurring at a straight earlier stage. For instance, client may lay down unrealistic cost limits or neglect to give clear sign about the practical dependence on the building. Normally, there is absolutely no clear information about the intended building life-cycle or maintenance requirements.
Inaccurate design decisions
The most common faults can be sorted as follows:
Failure to follow more developed design conditions in the decision of structural system and collection of materials
Ignorance of the basic properties of material. For example, failing woefully to make allowance for the differing thermal and moisture activities of materials found in combination.
Usage of new materials or systems that have not been carefully examined its success. This is often the consequence of uncritical reliance on manufacturers' literature quoting stimulated laboratory exams.
Misjudgement of consumer and climatic conditions under the materials will have to perform.
Complex details that have low probability of successful execution with an open up building site.
Poor communications between different parties such as design and structure teams.
Construction method
The construction tasks normally take place in less ideal conditions and always emphasize on fast completion scheduled to time constraint which frequently led to careless delivery. Some manufacturers of so-called high technology components have little awareness of the strictness of a building site or the specifications of accuracy possible under such conditions although only a little proportion of defects were attributable to faulty materials. Materials may easily be damaged during transportation, launching and unloading, unacceptable condition of storage on site and placing in position even although materials may be flawless upon leaving the manufacturer. The defects can be averted with by firmly taking greater treatment during all the periods during construction job, providing appropriate training to all or any the workers and staffs, and guaranteeing closer guidance.
User Activities
Defects may be brought on by unintended misuse due to the lack of knowledge on the right method of consumption or intentional functions of vandalism. This problem can be solved by providing much more information including the degree of seriousness useful and condition useful to the custom so that a much better output can be yield. Besides, some defects may be correlated to the users' financial conditions and also social attitudes. For instance, condensation is afflicted by the amount of money spent on heating and ventilating, and occupancy style.
Maintenance
Incorrect id of base of the defects may lead to unacceptable remedial work. It won't rectify the original defects but may deteriorate the health of the building further. Furthermore, negligence during inspection and repair works can lead to defects in recently satisfactory set ups or elements. For example, stepping on unprotected felted roof covering can drive the gravel in to the felt which can cause splits and trim and eventually lead to roof top leaking.
On the other side, defects often occur because of the designer's decisions. Designers often do not take into consideration the way the materials will act and respond toward other adjoining materials during building and through the life of the building. For example, the application of renewable, rotting or destroyed timber for floor joists will result in floor in the floor after completion. It really is obvious that a materials is often wrongly used even though the material itself is at perfect condition.
Effective communication between designers and structure workers supports solving problems. Sometimes, building workers readily put into action their own ideas of how to construct rather than speaking about with designers when they face with messy development drawings produced by inexperience designers. That is quite common in design-and-build form of agreements as the company stands to get contractual gain from drawing focus on design defects (Evans, 2005).
Building defects are a subject of matter for a various reasons:
The employer is eligible for what they're spending for. The presence of defects means that he / she doesn't get anything proportional of the amount paid for.
Defects might delay the completion of the job and therefore affecting the handover of the building. It is because it will take some time to examine and rectify the defects.
Lot of time and money could also be used up in discovering possible factors behind defects, especially to add blame.
There may be significant disruption and consequential damage if defects are to be corrected in occupied complexes.
Resources spent on defect rectification aren't available for use anywhere else.
Defects symbolize inefficiencies in development procurement procedures.
Design defects affecting maintenance
Civil
Inadequate provision for movement
Ignoring hostile environment and the weather effects
Inadequate structural design such as foundation
Ignoring variants in garden soil conditions
Ignoring load impact on structural stability
Exceeding allowable deflection limits
Ignoring wind influence on the structure
Inadequate concrete cover on the reinforcement
Improper locating conduits and tube openings at critical structural locations
Architecture
Narrow stairs, passages & doors
Incompatible surface finishes with climate
Specifying finishes which need complete replacement
Ignoring climatic results on external shapes
Inadequate joints between faces
Maintenance practically
Ignoring gain access to for maintenance equipment
Designing permanent fixing that ought to be removable for maintenance
Ignoring maintenance equipment availability
Ignoring maintenance requirements in the design
Civil
Damaged form work
Excavation too close to the building
Painting in unsuitable condition
Inadequate drinking water proofing and drainage
Insufficient reinforcement cement cover
Loss in adhesion between materials
Early form work removal
Poor garden soil compaction
Inadequate curing
Materials
Different thermal movement in dissimilar material
Selection of material which is unsuitable for the prevailing climatic condition
Use of non-durable material
Use of expired material
Poor material handling & storage
Inadequate provision for movement
This happens when designers ignore the spacing needed for contraction and development movements. Such moves will cause breaking of the structures which will bring about corrosion of the structural elements such as beams, columns and slabs. It will cause breaking on the wall that will influence the aesthetic value of the building. The most severe case related to inadequate provision for activity would be the structural collapse.
Ignoring hostile environment and the weather effects
The designers should select and specify the suitable materials which can handle withstand the prevailing the weather during building design. This can bring about less maintenance through the post-occupancy level. Problems occur when a designer can be used to certain weather condition in a region and then steps to another region which has different weather without giving consideration to the weather changes. It'll cause materials to deteriorate in a shorter time and may affect the other areas of the building.
Ignoring biological effects
Designers should know about the building location and type of plants and pests existing in that area or in the vicinity. Designers also needs to determine whether any special treatments are needed to prevent these natural attacks. These preventions should be specified in the design drawings with certain degrees of clarity. Failing to deal with natural factors may need continuous maintenance which can be avoided through the design and development stage.
Inadequate structural design such as foundation
Inadequate structural design happens when designers didn't design or under-design the structural elements of the building. This will likely lead to building's pay out or failures. Besides, it will cause breaking of the wall finishing.
Settlement is 'movements within a composition because of the distribution or re-distribution of launching and strains within the many elements of engineering. Base failures may be brought on by the changes in ground conditions affecting early footings, failing of base arches, and decay of timber hemorrhoids or chemical assault on concrete groundwork (Watt, 1999).
Ignoring versions in ground conditions
Soil conditions are almost the same generally in most places. But, land structure can vary greatly using places or conditions. Hence, designers should determine whether properties are able to be built onto it by identifying the land condition and structure. This can be done by perform proper soil exploration and surveyor geo-technical test. Poor earth condition may cause breaking of the structural elements or exterior and interior walls of the building.
Ignoring load impact on structural stability
The impact of movement resulted from physical or mechanical activities such as elevators, lifts, the vibrations of central air-conditioning systems or wind flow fill in high go up building might causes cracking on the wall surface. Besides, vibrations from heavy traffic, equipment and piling operations will pretty much produce the same impact of movements. The problem can't be solved before impact of the motion is isolated.
Inadequate concrete cover on the reinforcement
Insufficient concrete cover may lead to the corrosion of the metal bars and breaking of the cement. This is because the corrodents might reach the concrete reinforcement faster if there is limited cover or protection to the metallic bars. The failing of the metallic reinforcement may cause the inability in the framework.
Improper locating conduits and tube openings at critical structural locations
Some designers do not amend the layout of the mechanical and electric powered design which installs the conduits and pipes at an extremely critical location which can cause defects or cracking of the structural elements and damage to the electric and mechanical system of the building.
Incompatible coatings with climate
Designers should consider the environment, weather and environmental condition that the properties will subjected to before choosing ideal buildings' exterior surface finishes. Suitable colour and type of exterior building surface finishes should be selected carefully to be able to prevent environmental effects on the coatings. For instance, building with dark colorings painting might not resist heat during warm weather.
Specifying finishes which require complete replacement
Designers should prevent the consumption of surface finishes which require complete alternative after failure. On the other hand, finishes which are easily available and require minimum maintenance should be adopted. The use of wallpaper as wall coatings is not encourage as it needs total replacement unit if any part if it is damaged to be able to match the colour.
Ignoring climatic effects on exterior shapes
Designers should make sure that the collection of moisture, drinking water and dirt can be averted after the properties will be ready to be occupied. Proper designs which consider the climatic results on exterior shapes might lead to less maintenance need on cleaning and restoring damages due to climatic effects such as dampness, water and dust particles. Inappropriate exterior designs might cause normal water collection at the building roof covering which might constitute to moisture penetration in to the building.
Inadequate joints between surfaces
Designers should designate appropriate joints between constructions such as floor slabs and wall surfaces to accommodate the growth and contraction brought on by thermal. This is because insufficient joints may cause overlapping of the ground tiles and breaking of the surfaces such as wall space and tiles anticipated to thermal development.
Ignoring gain access to for maintenance equipment
Buildings should be made to allow for the maintenance access. The maintenance gain access to factor should think about the clearance of the maintenance staffs and equipment. Failure to provide necessary gain access to for the maintenance to be completed will obstruct the maintenance work and deteriorate the specific part further that will cause the raise in maintenance cost.
Designing permanent mending that ought to be removed for maintenance
Designers should prevent the usage of long lasting fixations which require constant maintenance and complete removal during maintenance works. All these will boost the maintenance frequency as well as the maintenance time would have to be carried out. Everlasting fixations that should be avoided are lamps, carpets and external windows.
Ignoring maintenance equipment availability
Building designs should be designed according to the current and existing maintenance equipment on the market. Designers should aware of the maintenance equipment on the market in building a certain building. For instance, problem may occur when cleaning a building exterior or windows in a high-rise building and also changing lights in a very high location. Maintenance cost may be accelerated if maintenance equipment is not available.
Inaccurate measurement
Inaccurate measurement happens when the development contractor wrongly gauge the building aspect size and the material mixture proportion such as concrete proportion. For instance, the changes or alteration of the gap between door and door structure or window and window body will causes drinking water and moisture penetration. Besides, the building contractor wrongly escalates the water content to the concrete mixture will deliver porous concrete which will causes corrosion to the steel reinforcements and then, collapse of the composition.
Damaged formwork
Damaged formwork will produce a honeycomb or porous concrete surface which diminishes the quality of the formwork. The porous concrete surface will permit moisture penetration which can cause corrosion of the material bars and cracking of the framework.
Inadequate water proofing and drainage
Water proofing and drainage of creating are normally being completed wrongly and inadequately. Inadequate drinking water proofing or water confirmation membrane may bring about normal water seepage or leakage through slab, wall membrane, balcony or deck. The building will be exposed to erosion, mildew, decomposition, and building damage if there is no proper waterproof membrane to prevent water penetration. For example, the building will expose to serious building defect when there is no water evidence membrane under the ground slab which helps to prevent ground drinking water from penetrate into the foundation.
Cold joints
Cold joints normally happen between old and new cement as the cement is poured in part and kept to dry before the remaining cement is poured. The dried concrete won't totally incorporate or fix jointly and lines will appear on the concrete. The cold joints will reduce the aesthetic value of the building. The serious case of chilly joints allows this inflatable water penetrate into the concrete gap which can damage the steel bars inside the concrete. Cold joints can be defeat by inserting reinforcement bars into the fresh concrete that will bind the new cement effectively.
Construction materials
Defects can be induced by the incorrect selection or specs of materials by the designers. Selection of non-durable or poor materials that is available at cheaper price may require lots of maintenance during post-occupancy period. The climatic factors must be considered during collection of materials as material's quality will be affected and require substitution very quickly. For instance, specifying indoors materials to be used at outdoor may cause the materials to perform irregularly. In addition, some materials which is highly adopted in overseas, might not perform effectively in Malaysia because of its hot climatic condition.
On the other side, the properties of materials should be considered when combining several materials together. That is because of the chemical reactions that might appear between them. For example, tile glue and cement will distinguish from each other when used jointly as thermal development of cement is higher than the tile glue. Selecting the materials must be done carefully as it will have an impact on the building quality and maintenance needs.
