Constructability also affects maintenance of a building. Poor constructability can lead to lower standards of construction. The more complex an assembly or technique, the greater the number of opera- tions involved and specialist trades required. Hence it is important to create designs which are simple to construct and easy to maintain. The two issues bear a relationship with each other and hence it can be concluded that, “easier is the construction process, the easier is the maintenance of the structure”.
The methodology adopted for the achievement of this goal is as follows:
- Preperation of list of factors that should be considered during planning and which effect constructability during execution of the projects.
- Preperation of list of factors, to be considered during planning and execution of projects, and which have adverse affects on maintainability during their service life.
It is a system for achievement of optimum integration of construction knowledge in construction process and balancing various projects and environment constraints to achieve maximization of project goals and construction performance. It is also a measure of the extent to which the design of a building facilitates ease of construction, subjective to overall requirements for the completed project.
While constructability does not necessarily add to, or improve the function or operating reliability of a project, the inclusion of construction knowledge and experience into the planning and design of a project can result in reduced installed cost and improved safety during construction. Labor and materials comprise the two most significant factors affecting project cost, schedule and quality performance. A constructability approach will make use of construction oriented expertise early in the planning and design of a project.
An important characteristic of constructability is that, the earlier the construction program is implemented; the more the costs will be lowered. Therefore in order to achieve more benefits constructability analysis should be performed during the planning and conceptual design phases, rather than in the field.
Factors Affecting Constructability
Mutual consent between the Designer & Constructor at early stage is beneficial
Design as well as drawings should be easy to read and understand with sufficient cross sections, properly cross-referenced. Construction process involves designing & making buildings; the working drawings form a link between the two activities. If the links were weak, then the product would not be worth. The drawing must be carefully thought off and thoroughly dimensioned.
Poor detailing is another major reason. As the design takes place on the drawing board, the designer must constantly check and amend it to ensure that it is workable & buildable. Designer should endeavor to produce simplest possible details, compatible with overall requirement of building; this opens way to efficient defect free work that will satisfactorily perform its end function.
On the other hand, the constructors should not be discouraged from suggesting changes and it is not advisable to dismiss the suggestions offered.
The design of building elements and details should encourage appropriate repetition and standardization, so as to reduce learning time and speed of construction. It is advisable to incorporate readily available standard products in the design and encourage their usage, so as to avoid the errors which may occur otherwise.
Planning and scheduling
Access, storage and distribution must be considered at the drawing board stage. It is often necessary to phase work so as to facilitate use of part of building for storage. It is very important to properly plan and schedule layout and detailing activities since they must be programmed in advance to precede fabrication or installation work with sufficient load time for proper material delivery or for other dependent activities.
The layout should allow the maximum utilization of mechanical plants, particularly for movement of materials. Where possible locations suitable for cranes and their bases should be identified and left clear.
The design should arrange work sequencing in such a way that a trade or specialization can complete all its work at a work place with as few visits as possible. The design should enable work to be carried out in a workmanlike manner without risk of damage to adjacent finished elements and with minimum requirements for special protection. Simple sequencing should enable each operation to be completed independently and without interruption. The sequence should assist the coordination of trades and minimum delay.
Award of works
Most of the projects today are complicated with number of services involved and hence require contractors and many sub-contractors to perform portions of the work. The contractor shall supervise and direct the work, using his best skills and attention. He shall be solely responsible to the owner for the acts and omissions of his employees, sub-contractors and their agents and any other person performing any work under the contract with him. Contractors and sub-contractors should be hired strictly on pre-qualification system for the quality, safety and liability. This should be strictly followed for the sake of uninterrupted work sequence.
Inspection and meetings on site
The project team participants responsible for constructability should be identified at an early stage in the project. The responsibilities should be very clearly defined at the beginning among the engineers, contractors, and fabricators etc. Full time inspection at the site by the engineer in charge is very important. Frequent visits by the designer should be planned to avoid any confusion and keep a check on the work so that the pace of work is not affected and no “short-cuts” are taken.
Sharing of knowledge
The majority of knowledge acquired by an individual during the construction of a project is not effectively communicated because of unreliable channels. Proper records shall be maintained of previously considered solutions or approaches and results of selected actions. This bank of information could be valuable. Knowledge of feasible solutions that were unsuccessful and should perhaps be avoided would be of great help.
Maintainability is a characteristic of design, whereas maintenance is the result of design. It is the ability to maintain in the least amount of time at the lowest cost.A large number of country’s resources are being employed on corrective or remedial measures to buildings and their services due to design and construction defects.
Factors Affecting Maintainability
There are defects that occur in the building if the civil design is inaccurate.
The areas that need attention include provisions for structural movement, effects of aggressive environments and weather conditions, biological effects, structural design of foundations, variations of soil conditions, load impact on structural stability, exceeding allowable deflection, wind effects on structure, inadequate concrete cover on reinforcement.
Maintenance problems can occur due to loopholes at the time of execution of work on site. These include inaccurate measurement, damaged formwork, excavation tools close to the building, painting in unsuitable conditions or on unsuitable surface, inadequate waterproofing and drainage, insufficient reinforcement concrete cover, cold joints, loss of adhesion between materials, premature formwork removal, poor soil compaction, inadequate concrete curing.
Various spaces when ill designed can lead to maintenance problems in the future of the building. Some of these can be listed as narrow stairs, passages and doors, not relating exterior material selection to climatic conditions, specifying finishing that needs to be repaired as a whole (such as wall), not designing the exteriors according to the local climatic condition and inadequate joints between finished faces.
Designer generally leaves the details of his vision to be worked out by draughtsman who are either inexperienced or unqualified to take this responsibility. In many cases, the designer leaves some details to be decided on site. Defects occur due to improper construction drawings i.e. lack of references, conflicting details and often lack of details.
The idea of designer should be communicated efficiently. Poor communication between designer and owner can lead to problems. Construction personnel should be involved from day one of the design because these are the people who will be ultimately constructing the facility. Poor communication, hiring of unqualified designers, lack of field experience of designer, his technical background etc do effect on the maintenance of building to some extent.
Material and manpower
Material and manpower are two critical resources employed in building industry. Therefore, these factors need special consideration. Ignorance of these like; unclear specification, not defining adequate materials, inadequate concrete mix design can lead to problems. Some other defects can occur by the use of non-durable materials, use of expired material, poor material storage and handling. Defects can also occur due to construction equipment by their improper use, its inadequate performance and also at times because of lack of required equipment. Inefficient, unskilled, untrained manpower can lead to lot of increase in maintenance problems during the life of building. Similar to the prequalification analysis of the contractors, the work of the workforce should also be prior tried and tested.
Award of works
Most construction contract documents contain provisions requiring the contractor to provide as-built records as well as maintenance and operational manuals.
Inspection and meetings
A large number of maintenance problems can occur in the later life of building because of inadequate inspection during the construction period. This includes lack of Quality control, lack of proper inspection, unqualified inspectors, and owner’s neglect of inspection and weaknesses of inspection in the implementing corrective action during job execution.
Certain factors that affect constructability were discovered during the research and listed down under different heads and investigation was done. Similarly, factors affecting maintenance were also discovered and listed down.
- In the first phase literature study was done.
- 10 groups were identified as major factors that affect constructability.
- 8 groups were identified as major factors that affect maintenance.
- In the second phase, a questionnaire was developed.
- List of all these factors and their details was prepared.
- In the third phase, survey was conducted.
- A survey was conducted to assess the relative effect of these factors.
The questionnaire survey was completed out by a respondent group as follows:
- Civil Engineers - 25%
- Architects - 25%
- Construction managers - 50%
- Simplicity and standardization of elements should be applied to the design.
- Information and better communication between designers and various constructional personnel involved in the construction process should be taken care of and that too, at an early stage.
- Proper planning and scheduling of various activities should be done by application of management techniques like CPM, PERT or by using softwares like PRIMAVERA.
- Award of works is a critical and deciding factor
- Cautious architectural design and inspection of site by the designer is important.
- Well thought of structural design by the civil and other services personnel like HVAC etc. need to be involved at design stage and they should be regular visitors to the site.
- Efficient contractors, skilled labour/manpower should be selected.
- Study of proper building material properties and their life span should be identified before selection/ application.