For decades, the idea of prefabricated, manufactured or modular homes has conjured images of trailer parks and low-income mobile home communities. In fact, many subdivisions have zoning restrictions against these types of structures in order to protect property values within the neighborhood. That, however, may be starting to change as the benefits of modular construction are more widely recognized, not only for housing but also for a variety of business and government applications. One notable example: Google recently announced plans for a significant investment into modular housing units for its employees in the San Francisco Bay area, where housing is both extremely limited and incredibly expensive.

What is Modular Construction?
Simply put, modular construction refers to structures that are built in a factory and delivered to the location where they are assembled and/or finished for either temporary or permanent use. Modular units may be up to 95 percent complete when they are shipped.

Modules are employed for a variety of purposes. Relocatable modules are suitable for temporary classrooms, job-site offices and showrooms. Permanent modular construction (PMC), a growing market in the U.S., is used for schools, government buildings, housing, health care facilities and hotels. Modules can be constructed from a variety of materials including wood, concrete, cold-formed or hot rolled steel or a combination of materials. Most manufacturers specialize in a particular type of construction. Depending on the requirements of the project, a hybrid solution in which modules are incorporated into traditional site-built construction may also be appropriate.

While most people involved in the construction trades are well-versed in traditional building practices, off-site construction requires learning new processes and new ways of thinking about how a building gets built. In modular construction, for example, dealers typically serve as the general contractors. As projects become more complex, both the manufacturers and the dealers become indispensable resources for project teams and building owners.

In the traditional construction model, temporary teams are assembled to handle the various aspects of each unique project. Because the contractors each have their own interests to protect, risk-aversion takes priority over collaboration. The end result is more waste and less productivity without an increase in quality or innovation of design. Modular construction reverses those results by replacing fragmented and unique, site-specific construction processes with streamlined manufacturing processes. Off-site manufacturing, rather than on-site constructing of structures, offers greater control over workflow as well as over the entire building design and production process. Teams stay together from project to project, improving efficiency and collaboration.

The Many Benefits of Off-site Construction
Compared with traditional buildings, which are fully constructed on-site, manufactured modular buildings offer many advantages:
• Weather isn't a factor. Because manufacturing takes place in a facility with a controlled environment, weather impacts and delays are not an issue. Workers, tools and materials are not subjected to extreme temperatures, wind or moisture.
• Construction schedules are shorter. Greater control over all aspects of the project reduces the time to completion.
• Costs are more predictable. Streamlined processes and greater coordination reduce mistakes, variability and material waste.
• Environmental impact is smaller. Cutting down on the transportation of materials, contractors and laborers to and from the building site reduces carbon emissions. Additionally, site disturbance is minimized (fewer trees are cut down, fewer natural elements are uprooted).
• Workers and equipment are safer. Factories and manufacturing plants eliminate unpredictability (weather, terrain, etc.) of the job site.

What to Consider
Despite its many positive attributes, modular construction will not be right for every situation. When considering off-site versus traditional construction, first evaluate the project based on performance factors including operational and capital costs, availability of skilled and unskilled workforce, the project's scope, the design, construction goals and the risk of financial loss.

According to the National Institute of Building Sciences - Off-Site Construction Council, modular construction is well-suited for projects with restrictive schedules (buildings must be operational quickly), projects that include multiple identical units (box forms with uniformity), and projects that allow for stakeholders (owners, designers and builders, in partnership with dealers and/or off-site product manufacturers) to be involved in early fabrication decision-making so that they are familiar with and prepared for the process.

Location also plays a part in the decision to build on-site or off-site. The National Institute of Building Sciences advises that the greatest benefit of off-site construction comes with "remote sites and highly dense urban sites, where on-site construction would be difficult to access, sites with a short build season, or sites with expensive land that require any means possible to reduce overall construction budgets." Furthermore, working within a building code jurisdiction that is open to off-site construction is extremely helpful. Some that are not as receptive may require extra steps for permitting and inspection that result in longer review and reporting cycles than on-site construction.