· Defination :
Prefabrication is the Practice of assembling components of a structure in a factory or other Manufacturing site and transporting complete assemblies to the construction site where the structure is to / be located.
· Process of Prefabrication :
An example from house building illustrates the process of prefabrication. The
Conventional method of building a house is to transport bricks timber, cement, sand, Steel and construction aggregate etc., to the site, and to construct the house on site from these materials.
In prefabricated Construction. Only the foundations are constructed in this way while
sections of (walls, floors, roof are Prefabricated with window & door frames included).-transported to the site lifted into place by a crane and bolted together.
· Uses of Prefabrication :
1. The most widely used from of prefabrication in building and civil engineering is the use of Prefabricated Concrete & prefabricated steel sections in structures where a particulars part on form is repeated many line.
2. Pouring Concrete section in a factory brings the advantages of being able to re-use moulds and the concrete cab be mixed on the spot without having to be transported to and pumped wet on a congested construction site.
3. Prefabricating Steel sections reduces on site cutting and welding costs as well as the associated hazard's.
4. Prefabrication techniques are wood in the construction of apartment slacks and housing developments with repeated housing units.
5. The technique is also used in office blocks, warehouses and factory buildings.
6. Prefabricated Steel and glass sections are widely used for the exterior of large buildings.
7. Prefabricated bridge elements and systems offer bridge designers & Contractors significant advantages in terms of construction time, safety environmental impact construct liability and cost.
8. Prefabrication can also help minimize the impact from bridge building.
9. Radio bowers for mobile phone and other service often consist of multiple prefabricated sections.
10. Prefabricated has become widely used in the assembly of aircraft and space craft with component such as wings and fuselage sections after being manufactured in different countries or states from the final assembly site
Advantages of Prefabrication :
· Self supporting readymade components are used. So. The need for work shuttering and scaffolding is greatly reduced.
· Construction time is reduced and buildings are completed sooner allowing an earlier return of the capital invested.
· On site construction and congestion is mini mixed.
· Quality control can be easier in a factory assembly line setting than a construction site setting.
· Prefabrication can be located where skilled labour is more readily available and costs of labour, power, materials, space and overheads are lower.
· Time spend in bad weather or hazardous environments at the construction site is minimized.
v Disadvantages of Prefabrication :
1. Careful handling of Prefabricated components such as concrete panels or steel and glass panels is required.
2. Attention has to be paid to the strength and corrosion-resistance of the joining of prefabricated sections to avoid failure of the joint.
3. Similarly, leaks can form at joints in prefabricated components.
4. Transportation costs may be higher for Voluminow. Prefabricated sections than for the materials of which they are made, which can often be packed more efficiently.
5. Large Prefabricated Structures require heavy-duty cranes & Precision measurement and handling to place in position.
6. Large group of buildings from the same type of Prefabricated elements tend to look drab and monotonous.
7. Local jobs are last.