Construction companies looking for ways to improve their rates of return and enhance their efficiency are increasingly turning to offsite building methods for all or parts of their projects, especially when time is a critical factor and access to a site is limited. For certain projects in particular, constructing components offsite can save money, streamline scheduling, improve quality, reduce safety risks, and minimize the environmental impact of the project.
Offsite construction may be defined as any building method in which the building components are fabricated to a greater degree of finish than the materials used in traditional forms of onsite construction, and are then transported to the site for assembly. There are several types of offsite residential building, including manufactured homes that are fully built offsite; and modular homes that are constructed in three-dimensional units, or “modules,” in a factory, which are then joined together and anchored to a foundation at a permanent site. But it is also possible to supplement conventional construction methods with components made in factories offsite, such as wall panels, precast concrete, MEP (mechanical, electrical, plumbing) systems, and bathroom pods. Homes built with modular or panelized methods are generally constructed to meet the same code requirements that apply to stick-built homes.
A key advantage of offsite construction is that it shortens build times and makes construction schedules more predictable than building onsite. The components of the home can be constructed in the factory while the site is being prepared and the foundation work is being done. As soon as the foundation is complete, the home can be assembled, generally in a matter of weeks or even days. This accelerated process can greatly reduce the interest payments on a construction loan, and can lower the risk of costly scheduling delays.
Building in a factory-controlled setting also has the potential to reduce costs because the materials are used more efficiently. As the building components are not exposed to the elements until the final phases of the project, they are far less likely to be damaged or compromised than if they were put together outdoors over a longer time span. The costs associated with waste and waste disposal are also reduced. Thus, offsite construction can help a project meet higher environmental standards and earn certifications from green building programs. In addition to generating less waste than conventional building, the factory-controlled construction process minimizes site disturbances, and allows for the construction of a tighter building envelope, which improves the energy efficiency of the home.
Constructing large parts of the structure offsite can also greatly reduce onsite safety concerns. As much of the construction is done in the factory, the tasks workers have to perform onsite tend to be less complex. Workers also spend less time onsite, and are therefore less exposed to hazardous conditions and to adverse weather. And because the assembly of the components is standardized, workers can become more specialized in their tasks both in the factory and onsite, which increases their precision and lowers the risk of making mistakes.
From the perspective of general contractors, offsite construction can alter the traditional project workflow, as it front-loads the planning and design decision-making process, and demands close cooperation with manufacturers of prefabricated components. Modular projects typically use the design-build project delivery system, which is more streamlined than the design-bid-build process.While this delivery system can minimize risks for the contractor, it can also increase the responsibilities associated with the project. Contractors who are unfamiliar with this approach to construction may wish to hire a consultant who can guide them in adjusting their scheduling and supply chain management methods, help them establish relationships with local building component manufacturers, and ensure compliance with state and local code and other legal requirements.