Prefabrication building isn’t new. It is believed that some degree of prefabrication was used even in Roman times for constructing administrational buildings in the empire. Prefabricated building also came into use during the industrial area with prefabricated metallic structures and elements.
Since then, prefabrication has evolved and specialised, and could represent the future of construction for their many advantages. Prefabrication can be used for any types of buildings and almost any height. One of the most recent records is located in China in the city of Changsha. A 30-story building was finished in 15 days and can withstand a 9-degree earthquake.
Prefab houses are not necessarily standardised nor mass produced, although the construction industry makes use of some of its advantages .The popularity of this technique is constantly growing in the construction world because of a variety of reasons that will be further discussed below.
- Speed of the process
Different parts of the house can be built off-site, from precast concrete structures or sandwich panels to kitchen or bathroom pods, or even the entire house. Moving the manufacturing of some of the elements of a house to a factory typically means that the time actually spent on-site is significantly diminished. Therefore, the time spent on the design process increases and the architects and engineers needs to be more connected to the manufacturing process.
If various parts of the construction process are moved offsite, less time will be spent at the construction site. Usually, the on-site time consists of installing the prefabricated elements, connecting all the installations and maybe adding some extra finishes. No matter the level of prefabrication, the installation of the elements is quick and requires reduced effort. Besides this, the time can be better managed, there are more reliable site deliveries and the delays due to bad weather are reduced.
- Quality of the final product
On-site traditional building techniques can’t offer the same quality of the final product because the process involves many risks and exposure to human error.
Factories have a better-controlled environment that offers an improved quality of the products that can be easily verified. By moving some part of the manufacturing offsite, the quality can be better controlled, resulting in less site related re-work and a more efficient process, both cost and time-wise. Greater manufacturing precision offers a greater quality of the final product.
- Safer working conditions
The construction industry includes risks for the workers that are usually addressed in the form of safety standards that are constantly updated to cover all the risks involved. Even with these rules followed, the industry still has many risks. In the case of prefabricated building, part of the work takes place in a safer factory environment which resembles the manufacturing industry.
With less time spent on site, the risks of injuries and other work-related health problems and diseases is significantly diminished.
- Less labour needed
The workforce skilled in the construction industry has diminished in many wealthy countries. The existing skilled workforce will soon retire and the young population show little interest in this sector. Therefore, the shortage of labour is a frequent problem.
Because much of the construction process takes place in the factory, the need for a workforce is not the same as in the traditional building techniques. In the case of volumetric modular construction, where the kitchen and bathroom are assembled offsite, there will be no need for specialised labour to deal with all the installation on site.
- Less traffic
In the construction industry, traffic problems related to onsite traditional building techniques is usually a problem for the neighbourhood.
If much of the construction processes are moved offsite and reduce the time actually spent assembling all the elements and components on-site, the impact of the increased traffic in the area of the construction is significantly diminished.
The cost-efficiency of prefabricated building is related to all the principles and characteristics discussed here. More than that, if in traditional construction methods the budget used for unpredictable costs can be only guessed, by moving some of the process offsite minimise the risk of re-work with positive effects on the overall budget. The saved costs can be even invested in better prefabrication techniques and a better quality of the chosen finishes.
- A sustainable technique
The construction industry generates the most waste and pollution, from the beginning of the construction process to the end of the building life, and even after demolition. The waste and greenhouse gas emissions related to the industry need to be managed and reduced as much as possible.
By using prefabricated building, the waste of materials can be reduced to near zero because the processes that take place in a factory are more predictable than on the building site. This means that the materials required can be calculated more precisely and the resulting waste reduced.
The greenhouse gas emissions can’t be totally avoided in the factory environment, but can be diminished as much as possible. One way of doing this comes from the reduction of the traffic and transportation of materials and skilled workforce needed due to shorter time spent on site.
Another sustainable-related advantage of prefabrication is the sustainability of the materials used. Usually, in the traditional construction techniques, the main materials used are concrete or brick mostly due to their lower costs. The offsite production encourages the use of more ecologically friendly materials such as cross-laminated timber or steel.
Depending on the degree of prefabrication, the construction can be easily disassembled and then relocated. The damage made to the site with new constructions can be reduced to a minimum.