Prefabrication is the practice of assembling components of a structure in a factory or other manufacturing site, and transporting complete assemblies or sub-assemblies to the construction site where the structure is to be located. The term is used to distinguish this process from the more conventional construction practice of transporting the basic materials to the construction site where allassembly is carried out. The term prefabrication also applies to the manufacturing of things other than structures at a fixed site. It is frequently used when fabrication of a section of a machine or any movable structure is shifted from the main manufacturing site to another location, and the sectionis supplied assembled and readyto fit. It is not generally used to refer to electrical or electronic components of a machine, or mechanical parts such as pumps, gearboxes and compressors which are usually supplied as separate items, but to sections of the body of the machine which in the past were fabricated with the whole machine. Prefabricated parts of the body of the machine may be called 'sub-assemblies' to distinguish them from the other components. The process and theory 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 and roof are prefabricated (assembled) in a factory (possibly with window and door frames included), transported to the site, lifted into place by a crane and bolted together. Prefabrication is used in the manufacture of ships, aircraft and all kinds of vehicles and machines where sections previously assembled at the final point of manufacture areassembled elsewhere instead, before being delivered for final assembly. The theory behind the method is that time and cost is saved if similar construction tasks can be grouped, and assembly line techniques can be employed in prefabrication at a location where skilled labour is available, while congestion at the assembly site, which wastes time, can be reduced. The method finds application particularly where the structure is composed of repeating units or forms, or where multiple copies of the same basic structure are being constructed. Prefabrication avoids the need to transport so many skilled workers to the construction site, and other restricting conditions such as a lack of power, lack of water, exposure to harsh weather or a hazardous environment are avoided. Against these advantages must be weighed the cost of transporting prefabricated sections and lifting them into position as they will usually be larger, more fragile and more difficult to handle than the materials and components of which they are made.
Prefabricated steel and glass sections are widely used for the exterior of large buildings. Prefabrication saves engineering time on the construction site in civil engineering projects. This can be vital to the success of projects such as bridges and avalanche galleries, where weather conditions may only allow brief periods of construction. Prefabricated bridge elements and systems offer bridge designers and contractors significant advantages in terms of construction time, safety, environmental impact, constructibility, and cost. Prefabrication can also help minimize the impact on traffic from bridge building. Additionally, small, commonly-used structures such as concrete pylons are in most cases prefabricated. Prefabrication has become widely used in the assembly of aircraft and spacecraft, with components such as wings and fuselagesections often being manufactured in different countries or states from the final assembly site. However this is sometimes for political rather than commercial reasons - e.g. Airbus
Advantages of prefabrication
1. Self-supporting ready-made components are used, so the need for formwork, shuttering and scaffolding is greatly reduced.
2.Construction time is reduced and buildings are completed sooner, allowing an earlier return of the capital invested.
3.On-site construction and congestion is minimized.
4. Quality control can be easier in a factory assembly line setting than a construction site setting.
5. Prefabrication can be located where skilled labour is more readily available and costs of labour, power, materials, space and overheads are lower.
6. Time spent in bad weather or hazardous environments at the construction site is minimized.
7. Less waste may occur
8. Advanced materials such as sandwich-structured composite can be easily used, improving thermal and sound insulation and airtightness
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 voluminous prefabricated sections than for the materials of which they are made, which can often be packed more efficiently.
5. Large prefabricated sections require heavy-duty cranes and precision measurement and handling to place in position.
6. Larger groups of buildings from the same type of prefabricated elements tend to look drab and monotonous.
7. Local jobs are lost
Prefabricated Building material
Prefabricated building materials are used for buildings that are manufactured off site and shipped later to assemble at the final location. Some of the commonly used prefabricated building materials are aluminum, steel, wood, fiberglass and concrete. Prefabricated metal buildings use galvanized steel and galvalume as the chief materials for building. Galvalume is a form of steel coated with aluminum-zinc.This is to protect the building against corrosion, rust and fire. It also provides a sturdy and protective covering to the prefabricated building. Almost all the components of a metal building such as beams, frames, columns, walls and roofs, are made of steel. Most prefabricated military buildings use steel or aluminum frames. Synthetic materials are used for the walls and roofs. To provide enhanced security, a combination of both metal and cloth materials are used. Plastic flooring materials can be quickly assembled and are very durable. Prefabricated building materials used for small prefabricated buildings are steel, wood, fiberglass, plastic or aluminum materials. These materials are cheaper than regular brick and concrete buildings. Materials like steel, fiberglass, wood and aluminum are used as prefabricated building materials for sports buildings.
These materials provide flexibility and are preferred for making structures and accessories like stands and seats for stadium and gyms. For making low cost houses, prefabricated materials likestraw bale, Ferro cement,Calcium silicate products,composites and other cheap wood based materials are currently being used. Calcium silicate bricks are strong and durable. Ferro cement consists of a cement matrix reinforced witha mesh of closely-spaced iron rods or wires. In this type of construction, the techniques used are simple and quick. Using prefabricated materials one can make durable, water and fire resistant and cheap prefabricated buildings. Most of the prefabricated building materials are eco-friendly and affordable. Prefabricated Buildings provides detailed information on prefabricated building,prefabricated metal buildings, small prefabricated buildings, prefabricated building manufacturers and more. Prefabricated Buildings is affiliated with Manufactured home floor plans
What Are Prefabricated Building Materials
These are construction materials specifically designed to be manufactured offsite but later brought on to the real site.They are made up of factory built components which are assembled away from the main location. The most considered types are the Galvavolume and the Galvanized steel. Steel coated with aluminum zinc are the most commonly preferred prefabricated building materials. They prevent corrosion, fire and rust from destroying the building. This greatly reduces the construction cost. Fabricated building materials are commonly used in the military buildings to improve on the security. The builders normally combine both cloth and metal materials when flooring. These materials are very durable and can easily be assembled. The ceiling is commonly made up of frames, beams, walls and roofs of steel. Most commonly used fabricated materials are fiber glass, concrete, steel and aluminum. They are given consideration because of the hardness..
is a building process in which elements or modules of the structure are prefabricated at plants, then transported to the construction site for installation. Using this method can reduce the time of building, also saving construction cost. Prefabricated construction is now widely applied for new houses or other building structures like bridge, tunnels, culverts, water supply system… The benefits of prefabricated construction method is from the fabrication of standard components on factory floor. This production is less time consumption compared to actual condition of construction process. The prefabricated elements are transported to the site for installing process. At the site, the modules are unloaded, moved into position with the support of heavy cranes, and assembled to form a designed building.
Together with the fast assembly,prefabricated construction also saves a lot of money on the construction project. By using standard patterns, the building materials are saved at the manufacturing factories. This help to reduce the waste in formwork and other materials that can occur during traditional building procedures. Another considerable profit using prefabricated construction method is the energy efficiency. Because the prefab elements of a panelized home are precut, they fit snugly together, making for a tighter edifice. This means less effort for heating and cooling, resulted in lower energy bills.
The rapid development of prefabricated houses has led to the increasing of construction templates that homeowners have more choice for designs of their houses. By combining these templates, it is possible to design the layout of the house, specify the dimensions of each room, and build a home that is exactly to the specification of the owners.
There are also complex building plans for prefabricated construction that can be adjusted slightly and still have the benefit of using materials of standard lengths, widths, and textures. Prefabricated houses are not the only type of construction structures that can be produced using prefabrication construction method. As mentioned above, this method is widely used in many types of constructions like bridges, culverts or even swimming pools.
Prefab Housing Cost:
Buyers can typically expect to pay less for a prefab home than they would for stick-built construction. Modular homes do offer pricey customization, but the material costs still decrease with assembly-line construction. Because prefab home parts like windows and walls are made uniformly, there is no need for skilled workers to manufacture parts individually, which drives down costs. Also, factories, unlike most individual tradesmen, can buy the supplies in bulk. Prefabricated houses are constructed indoors and away from the weather, which also reduces delays and subsequent costs.
Prefabricated houses, like stick-built homes, do not have fixed prices, so buyers can negotiate. In general, they can expect to pay 10 to 25 percent less for prefabricated houses over stick-built construction. Typically, land is the biggest cash outlay for a prefabricated house. And, depending on your skill level, construction could be the other big expense. People who ordered Sears, Roebuck and Co. homes in the 1900s usually possessed carpentry skills, but mostmodern homeowners wouldn't feel comfortable laying their own foundation.
There are other regulations for building, including zoning restrictions, survey requirements and electrical and water hookups. Some companies offer their own services – for an extra fee, of course. Once buyers have the land and the house they want, financing can be a hurdle. Manufactured homes aren't considered real estate until they are permanently installed, so it can be more difficult to get financing for them. Even then, manufactured homes can depreciate in value, so lenders are less likely to give out loans. Modular homes, however, do not suffer as much from this lower- quality stigma, so financing for them is more similar to that for stick-built houses.