What is Prefabrication?
Prefabrication is the process of casting and assembling components of the structure in a factory, it includes the process of making, transporting and installing the complete assemblies or sub-assemblies of a structure in the construction site.
In the conventional method of construction brick, cement, aggregates, steel are brought to the site. By this material construction of building is carried out. But in prefabricated construction only foundation work is carried out in the site, while the other elements like wall, floor, roofs are prefabricated in a factory, then transported to the site and it is placed by using crane.
Prefabricated structures are very useful where the buildings require more number of repeating or same units or multiple buildings are constructed in the same type. The most widely used form of prefabrication in the building is concrete structures and steel sections. Prefabricated structures are very useful when normal construction process is not possible at the site and material availability is difficult in the site.
Civil engineering requirements:
- Complete the construction within the planned time:
By using prefabricated parts they are largely made and assembled and then transported to the construction site. Hence overall construction time is much lesser than the conventional construction process.
- Cost of the building construction should be less:
Prefabricated building members reduce the overall construction cost by mechanization and automation of manufacturing facilities, utilization of skilled labour reduces the factory made prefabricated parts waste.
- Achieving the required finish and performance of the building:
Using skilled labours in the factories for making the prefabricated parts, it is possible to assure the quality of the product and workmanship. Availability of advanced machinery promotes the quality of manufactured prefabricated element.
- Less construction time:
Manufacturing time of prefabricated element is less when compared to conventional method because works in the prefabricated production is standardized and organized, so the manufacturing time is less.
5 .Project completion in on time:
Seasonal variation affects the work in conventional method, but in prefabrication there is no such a problem.
- Material availability:
In construction places non availability of material creates the major problem in the progress of the construction.
- Quality of building:
Prefabrication is more reliable in the quality of out coming products from plants because of skilled labour testing facilities, processes control procedure, quality control systems.
- Congestion of work site:
The prefabricated parts are made in the factories there by storing of raw material near the site is less, because of this reason prefabrication promotes uncongested workplace environment.
- Skilled labour, power, equipment:
Requirement of skilled labour, power and construction equipment is very less in construction site when using prefabricated parts.
- Rebuild the structure in new place:
In prefabricated disassembling and rebuilding the structure is very simple in new location without any major damage.
- Durability and versatility:
Because of prefabricated elements produced in bulk quantities by using latest machinery. It is possible to improve or incorporate new changes within the minimum time is possible.
Disadvantages of prefabricated structures:
- Prefabrication plants require huge initial investment for infrastructure development.
- Transportation of prefabricated structures from factory to construction site is required hence there is additional cost.
- Large prefabricated structures need heavy cranes for handling and placing the structure in proper position.
- Group of buildings having the same type of prefabricated elements make confusion.
- Jobs for local people may be lost, since prefabrication is out sourced.
- In some cases manufacturing of prefabricated structure may not be reliable in quality or delivery time.
- Planning of building have some restriction, because of standard sizes of prefabricated elements.
- Damage of prefabricated elements is possible while transportation.
- Precautions to be taken for strength and corrosion resistance, leaks in joints.
Types of prefabrication methods:
- Plant prefabrication
- Site prefabrication