Modular construction has been a hot topic in the construction world in the last few years. What are the advantages and drawbacks of such methodology? Let’s find out.
Modular construction 101
Modular construction is a process in which a building is constructed off-site, under controlled plant conditions, utilizing the same materials and designing to the same codes and standards as conventionally built facilities (often about half the time).
Buildings are produced in “modules” that when put together on site, reflect the identical design intent and specifications of the most sophisticated site-built facility — without compromise.
Just like Legos
Modular construction is shedding the stigma of “prefab,” “manufactured homes,”or the vintage “double-wide trailer.” Upscale homes, apartment complexes, and even major hospitals are going… modular. Case in point: Bouygues Batiment International, in collaboration with their modular construction laboratory Dragages Singapore, has recently celebrated the completion of the tallest building tower ever built from modular construction, the Clement Canopy buildings in Singapore. Standing 40 stories tall, the Clement Canopy is a housing project in the heart of a residential and student district in Singapore. It consists of two towers measuring 459 feet each (the tallest ever to be built in modular concrete). The building is made up of 1,899 modules and offers 505 luxury residential apartments. The majority of the project was manufactured off-site before the modules were assembled on-site.
In this era of automation, the traditional model of constructing homes and buildings (where materials arrive at the project site and are cut and erected by specialists) is being more closely examined due to the waste, complex timelines, and inefficiencies that are often present on a jobsite. Instead, many successful projects are taking an automated assembly-line approach that is different from the manufactured homes and buildings of yesteryear. Manufacturing occurs in a factory environment, with on-site work similar to snapping building components into place, not unlike the ever-popular Lego building blocks.
Modular construction bring many benefits:
Firstly, modular construction gets rid of jobsite issues like access routes and traffic or security and storage of materials. Factories are typically located near shipping hubs, helping the flow of materials while reducing shipping costs. They are also located in neighborhoods where shift work can be the norm, hence construction work can take place “around the clock” if needed.
The modular process also enables some contractors to do foundation work at the same time others are building walls and components. This simultaneous construction setup gets a jump on the structure, with walls going up as the foundation cures. With such schedule advantages, the Modular Building Institute estimates that projects are completed 30 to 50 percent faster than mainstream construction. In the case of modular homes being constructed in California’s Napa Valley by Factory_OS, 1,300-square-feet structures are being assembled in only four hours (from foundation to turning the lights on)!
Reducing on-site measurement and construction work can lead to a much more seamless building process that avoids the sort of mistakes that can grind a whole project to a halt. That being said , building with components requires a new level of design and control. Instead of the typical mechanical, electrical, and plumbing process that takes place before interior and exterior finishes are complete, the modular building depends on chase ways (channels for electrical wire and communication cables) and plumbing components that click together upon assembly. It is absolutely crucial that each component is engineered to high standards so each piece fits perfectly with its neighbor.
Building information modeling (BIM) tools provide the key to much of the advancements in modular assembly as they allow for a detailed 3D visualization of components to make sure that the finished parts fit. BIM also provides the methodologies to detail each component for precise manufacture that may include wall-assembly templates and jigs, sub-assemblies that fit within wall frames, as well as automotive approaches such as robotic welding.
According to a National Association of Home Builders (NAHB) study, an estimated 8,000 lb. of waste is generated from the construction of a typical 2,000-square-foot home. With controlled factory settings, this waste is significantly reduced because the excess materials can be recycled onsite into other processes, and controlled storage reduces material damage from weather.
The factory setting helps maximize labor effort by automating repetitive, simple tasks and assigning workers to smaller and more specialized tasks, helping to speed construction. On-site construction labor costs tend to be higher because the labor is more skilled, with workers responsible for a much wider range of tasks and a greater degree of customization in the end product.
But not everything is perfect…
One of the main drawbacks of modular construction is that projects can be large, but room sizes are usually smaller. The pieces of a modular home cannot be too large to transport, hence they can’t generally be more than 14 to 16 feet wide and 60 to 75 feet long.
Furthermore, modular projects are typically paid for in advance or financed on a step-by-step basis. Such can be a major financial strain on smaller players.
Last but not least, some local authorities may not allow you to build a modular home or facility. Aspiring project leads will want to confirm that the jurisdiction where they want to purchase land and setup the structure will allow such.
It’s important to remember modular construction represents only a small portion of the construction industry. “In the U.S., modularization is only 3% of current construction,” says T.G. Jayanth, Capital Projects Expert at McKinsey & Co. But given its many benefits, it is bound to experience significant growth.