In general, modular construction involves the production of standardized structural parts in an off-site facility, which are then assembled on-site. Terms such as “out-of-site construction,” “prefabrication” and “modular construction” are used interchangeably. These concepts cover a variety of different methods and systems, from single components that are clipped together using standard connections and interfaces to 3D volumetric units with complete fixtures.
Modular construction has been a cost-effective alternative at some historic times, but its success has been short-lived. It enjoyed post-war booms in the United Kingdom and the United States, when there was a need for rapid reconstruction and social housing, when wartime factories were vacant, and when there was a shortage of steel and labor. But its popularity decreased as supply and demand began to increase in the United States; the collapse of the United Kingdom’s 1968 apartment-tower also raised concerns about the safety of prefabricated buildings.
Today’s world, modular construction is witnessing a new wave of interest and investment, and a number of factors indicate that it may have renewed durability.
How does Modular Construction Work?
Modular buildings are constructed in parts away from construction sites before being shipped to the desired location where they are assembled in the final design of the building. 60-90 percent of the work is performed in a factory-controlled environment, either as a complete structure or as a modular subassembly for a larger project.
This off-site construction allows the use of lean manufacturing methods to produce prefabricated modules. These modular units can be mounted end-to-end or stacked to build various configurations. The modular construction process is completed on site using inter-module (or inter-connect) connections to link the units together.
Types of Modular Construction
Permanent Modular Construction (PMC)
Permanent modular construction is a sustainable building system that uses lean manufacturing methods to prefabricate single-or multi-storey buildings in modular parts. PMC modules may be tailored to existing buildings or installed on their own. These modules can be completed with MEP appliances and interior finishes in less time than their counterpart.
Relocatable Buildings (RB)
Relocatable Buildings are partial or complete assemblies, assembled in a manufacturing facility using a modular construction process. While these buildings can be moved, they comply with building codes and state regulations. Relocatable buildings are designed to be reused several times and relocated to different sites; they are not permanently attached to real estate, but are constructed in compliance with the manufacturer’s guidelines and local codes.
Some common applications include construction site offices, schools, medical clinics and retail outlets. RBs offer ease of relocation, quick installation, low-cost reconfiguration, versatility and accelerated depreciation for accounting purposes.
The Advantages of Modular Construction
Modular construction is a sustainable, efficient, cost-effective and innovative technique to be considered when designing a project. This section describes some of the benefits of this construction method.
Saves Time
The obvious is that the modular construction allows a portion of the work to be completed in a factory while the site works and the foundations are carried out simultaneously on the site. This time-saving advantage keeps the project on budget and accelerates construction time while still being effective. It is possible to save 30 to 60 percent of the total schedule with a modular approach.
No Possibility of Weather Delay
In addition, by producing modules in a regulated environment, questions about the weather delay in the construction of modular units are practically eliminated. It also provides workers with better and more comfortable environments to be more efficient and to deliver a higher quality product. Also, modules often arrive on-site, usually complete with flooring, cabinets, counters, plumbing and electrical fixtures and appliances, requiring minimal effort and time to be ready for use.
No Need to Store Materials
Another advantage of modular construction is the handling of materials. When a site is tight in space, e.g. in a compact urban environment like Greater London Area, staging and moving materials around is difficult. This causes clutter, slows down work, and creates fear of burglary. By constructing modules in a factory, construction sites can stay cleaner and safer and have more space to function and move about freely.
Lower Labor Costs
The labor economy is a significant and potentially contentious benefit. Skilled labor is in short supply for building in most areas and can be very costly in cities for a number of reasons. Without going into politics, this leads to real difficulties in attempting to build a building for a defined budget and timetable. Modular allows the coveted skilled workers to remain in fixed locations under controlled and safer conditions, as indicated above. Modular plants may be located to attract those competitive workers and take advantage of important access to raw materials and logistic connections, such as highways and rail lines, common in other industries, such as automotive and technology products. Labor savings can vary widely, but there is a potential for up to 25% of construction costs.
Lower Volume of Waste
According to a recent UK study, a reduction of up to 90% in materials can be achieved through modular construction. As the environment is a growing concern in the construction industry, modular strategies to reduce the amount of waste for each project are becoming more popular. Efforts are also being made to maximize recycling in the factories that have put the building portions together.
The Disadvantages of Modular Construction
The main disadvantages of modular construction apply in the housing sector, and they are summarized below.
Size
Modules must be transported from the factory to the construction site, and this must be properly planned. The size and properties of each element must be considered in order to determine the mode of transport that will not cause damage. In the case of prefabricated homes, this may be a drawback, as rooms are usually smaller than those in conventional homes.
Financing
When financing modular homes, banks will normally issue a two-stage loan. They are known as construction-to-permanent loans. In many cases, owners will not be able to obtain a traditional bank loan until the construction of the home is complete. Financing the project up front is a challenge in this case.
Land Restrictions
In certain areas, local authorities will not permit the construction of modular homes. It is therefore necessary to read about local laws before deciding to buy them.
Conclusion
Modular construction produces structurally strong buildings with less time than traditional construction methods. It also maintains a high degree of quality control, decreases site disturbance and reduces vehicle traffic. Another advantage of modular construction is that it increases the overall safety and protection of workers.
It is necessary to consider all construction methods to decide which methodology is most fitting for your project. In general, off-site construction is preferred during the earlier stages of project planning in order to prevent further redesign. This does not, however, prohibit the owner from redesigning a building originally planned for site construction in a modular version. If your main concern is to use more sustainable building techniques, modular construction is certainly a methodology to be considered-provides a managed environment that reduces waste.
