Building production
is the organization and management of the plans, equipment, materials and labour involved in the construction of a building, while at the same time complying with all codes, rules and contractual stipulations.
The procedure should be designed to run efficiently, to keep the costs low and to allow returns on the investment to be realized as early as possible.
Industrialised Building
a technique of construction where by components are manufactured in a controlled environment, either at site or off site, placed and assembled into construction works.
Open Building
is an approach to the design of buildings that is recognized internationally to represent a new wave in architecture, but a new wave with roots in the way ordinary built environment grows, regenerates and achieves wholeness.
Rationalization of Production
the process of improving the means and methods of social production in order to improve production efficiency. The rationalization of production includes an improvement in equipment, production processes, and the organization of labour, production, and management
The building production commences when the client starts to seriously consider investing in a structure and does not end until the finished building is in use.
The process is divided into stages which follow in logical sequence. Each stage is terminated by a decision. See tables.
Methods of construction
The methods of constructing buildings refers to the way in which units and components of the building structure are produced and assembled. The manner of organizing this process differs from region to region and depends on the level of technology and the materials available. The following are methods of construction:-
1. Traditional Building
In traditional building, forms of construction are those evolved by the traditional building crafts, particularly those of walling, roofing, plastering, carpentry and joinery. This method is a process of combining many small units. Most of the fabrication and assembly takes place at the site and usually in the position that the unit is to occupy in the completed structure. Within each tribal culture, traditional building results in structures that are similar but differing slightly, depending on the specific requirements and site.
2. Post-traditional Building
The post-traditional or conventional method of building mixes traditional and new forms of construction, involving both the old crafts and newly developed techniques based on new materials. To some extent traditional building has always been in a state of change, but the introduction of Portland cement and mild steel has made it feasible to construct large and complex buildings and with this arises the need for efficient organization of the construction process.
The amount of on-site fabrication has been reduced by the introduction of prefabricated, factory-produced components, especially in the field of joinery and carpentry (windows, doors, cupboards, roof trusses, etc.). Reinforced concrete and preformed steel lend themselves to off-site fabrication of parts and only their assembly on site.
Post-traditional building varies from the traditional mainly in the scale of the work carried out and in the use of expensive machinery for many operations. The use of prefabricated, standardized components reduces the amount of skilled labour, but at the same time reduces the freedom of the designer in meeting varying design requirements.
3. System Building
System building is a method in which most of the building's component parts are factory-produced and siteassembled.
The main advantages in system building are the possibilities for efficient factory production of large numbers of similar building elements and the reduced period of time necessary for assembly at the site.
A disadvantage with this method is the high level of accuracy required for setting out and foundation work since the nature of the components and the principles of the system are such that mistakes are difficult to correct during the assembly process. The components (e.g., wall, floor, ceiling and roof elements) are usually related to a specific building type, such as houses, schools or warehouses or to a restricted range of types. The design of buildings produced by this method is inflexible and limits the possibility of adjusting to specific requirements at a certain site or to a local building tradition.
The methods of System Building through Prefabrication
Prefabrication is the manufacture of building components either on-site (but not in-situ) or off-site in a factory. The use of prefabricated components can reduce the need for skilled labour at the site, simplify construction by reducing the number of separate operations, and facilitate continuity in the remaining operations. However, prefabs are not necessarily timesaving or economical in the overall construction project. For example, the use of prefabricated lintels may save formwork and result in continuity in the bricklaying work, but would be uneconomical if a lifting crane is required at the site to place them, when it is not required for any other purpose on the job.
-On-site Prefabrication
On-site prefabrication may be of advantage where a number of identical components such as roof-trusses, doors, windows, gates and partitions are required. Once a mould or prototype has been made by a skilled craftsman, a number of identical components can be produced by less-skilled labour. Prefabrication of such items as roof-trusses will also make for more convenient and effective production than construction in-situ.
It is advantageous to prefabricate some concrete components. Components for elevated positions require simpler formwork if cast on the ground or in the ground so that the soil can be used to support the formwork. Prefabrication eliminates the waiting time for concrete components to harden sufficiently for subsequent on- site operations to continue, but the weight and size of concrete parts may make prefabrication impractical.
Local production by farmers of adobe bricks, burnt bricks, soil blocks, etc. is not normally referred to as prefabrication although similar planning and organization are required for the production of these units as for production of prefabricated building components.
-Off-sitePrefabrication
Factory production of components requires capital investment in machinery and premises, a high degree of organization of work, standardization and a steady demand for the products. Building components, which can be economically produced in a factory, essentially fall into three categories:
§ Those which have a high degree of standardization and are in great demand, so that mass production, utilizing the greater efficiency of modern factory production, is feasible, e.g., bricks, blocks, pipes, windows, doors and building hardware.
§ Those which incorporate materials or finishes that are exclusively or more efficiently produced with factory based techniques, e.g., metal components, plastic items, galvanized items and baked-paint finishes.
§ Those which make use of new factory-based techniques and machines, e.g., laminated-wood beams, prestressed concrete beams and insulated-sandwich panels.
In order to limit the variety in size of similar components, to facilitate their assembly at the site, and to make them interchangeable between different manufacturers, building components are manufactured in standardized dimensions based on an accepted system of dimensional coordination. Such preferred dimensions are given in standards together with specifications for minimum requirements of technical performance. When the experience gained in factory production of components increases, the technique will be applied to components of increasing size and complexity (e.g., wholly finished wall elements) and this will increase the need for dimensional coordination.
One system of dimensional coordination uses the international basic building module of 100mm. The reference system establishes a three-dimensional grid of basic modules, or very often multi-modules of 300mm, into which the components ft.
The modular grid does not give the size of the component but does allow space for it. In order for the component to fit correctly, it will always be slightly smaller than the space allowed for it. The system must allow for some inaccuracy in the manufacturing process and changes in size due to changing temperature and moisture conditions.
This is expressed as a tolerance in size. For example,
a window which is allowed a basic size of 1200mm for its width is produced with a working size of 1190mm and a manufacturing tolerance of 5mm, which is expressed as 1190 + 5mm. The actual dimension of a window delivered to the site would be somewhere between 1185mm and 1195mm. The joint would be designed to take these deviations into account.
Modular-size concrete blocks are 290mm long and modular format bricks are 190 x 90 x 40 or 90mm actual size to allow for 10mm mortar joints and plaster.
The actual size of openings will then be 1220mm. In this process the designer has a responsibility to specify tolerances that can be achieved with available craftsmen and factories. It will be easier to fit factory produced window and door casements, which are made to standard modular sizes, if these sizes are also used when bricks and blocks are manufactured locally.
The common brick size of 215 x 102.5 x 65mm allows for laying four coarses to 300mm vertically and four brick lengths to 900mm horizontally, if 10mm joints are used. See figure attached for dimensional of a window of its width being 1200 mm
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