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Off-Site Modular Construction Improves Quality and Safety of Projects

By Sheryl S. Jackson

Prefabrication is not a new concept for the construction industry. In the early 1900s prefabricated houses were delivered to customers via mail order1 and in World War II Quonset huts were shipped to military sites around the world.2 Customers took delivery, “unboxed” their building and put it together.

A 2011 survey of contractors found that 98 percent of respondents use some form of prefabrication or modular construction but the use is limited to a small portion of the project. Only 37 percent use it on 50 percent or more of the total individual project.3

Of the 800 architecture, engineering and contracting professionals surveyed who use off-site manufacturing:
• 66 percent report that project schedules are decreased — 35 percent by four weeks or more
• 65 percent report that project budgets are decreased — 41 percent by 6 percent or more
• 77 percent report that construction site waste is decreased – 44 percent by 5 percent or more3

Modular construction differs from prefabrication. In prefabrication, a system may be built off-site but it involves one trade, such as plumbing, explains Eric Hedlund, executive vice president and chief operating officer of Sundt Construction. Modular construction involves several trades working together to build a unit such as a bathroom pod, walls with electrical and plumbing installed, or mechanical systems.

Sundt, a member of the Arizona and San Antonio AGC chapters as well as AGC of Texas Highway, Heavy, Utilities and Industrial Branch, Arizona Builders’ Alliance and AGC of California, has a task force that evaluates potential new projects for opportunities to utilize off-site modular and prefabrication construction. “A recent project for student housing was designed conventionally to be built in the fi eld,” he says. “We converted the project to a modularized approach and submitted a bid. This innovative approach served as a competitive differentiator for us,” he says.

Hotels, student housing, highrise residential, factories, office buildings and hospitals are ideal
for off-site modular construction because each building has components that repeat. “We can build 750 identical bathrooms or 125 identical hotel rooms in a factory and transport them to the jobsite,” says Mark Konchar, senior vice president of Enterprise Development for Balfour
Beatty Construction, an AGC member in eight states. Hospital headwalls complete with system components in place – oxygen and other medical gases, electrical, data and plumbing – can easily be manufactured off-site, he adds.

There are a number of benefi ts to off-site modular construction but at this time, direct cost savings may not be significant on many projects, points out Hedlund. “We are all learning how to price modular construction in the fi eld,” he says. “There are costs automatically included for traditional construction that we believe are still added to estimates but will be eliminated once contractors have more experience with modular construction and understand what can be reduced.”

Contractors in the United Kingdom have more experience with modular construction, says Konchar. “Our parent company’s experience in other countries, especially the United Kingdom, has
given us invaluable knowledge as we’ve introduced off-site modular manufacturing in our U.S. projects.”

It makes sense for everyone in the construction industry to consider off-site modular manufacturing, says Konchar. As more companies incorporate lean principles into their business philosophy; introduce technology, such as building information modeling, throughout the construction process; and move toward environmentally sustainable processes, off-site manufacturing makes sense, he points out.

One of the more visible modular construction projects underway today is a 32-story residential tower that is part of the Atlantic Yards development in Brooklyn, NY. A total of 930 modules will be built and fi nished to nearly live-in ready status in a factory, then transported to the site and put together to build 363 apartments.

As off-site manufacturing becomes more common, costs will be easier to control but a significant, immediate benefi t is a more efficient use of employees, says Hedlund. “Many areas of the country have seen a decrease in the labor force,” he points out. “The loss has affected all levels, from trade staff to project managers.” This decrease in the labor force will not change in the near future. “For every 10 people who have left construction, only one will return.”

The ability to bring different trades together in one location to manufacture units for a building
not only provides an efficient, production-line approach to construction, but it can extend an employee’s career, says Hedlund. Experienced workers will fi nd the physical demands less stressful as they work at table-level height rather than on fl oors or step ladders, and less experienced people will develop skills more quickly as they learn in a controlled environment, he points out. “We’ll also
be able to attract more skilled employees who want to work in a cutting-edge setting.”

Manufacturing units that can be put into place at the worksite does have a positive effect on the construction schedule, which translates into savings for the client, says Konchar. Schedules are more predictable because units are produced in a controlled environment that is not affected
by weather, daylight or local restrictions on construction activities. Although increased use of modular construction in a project often shortens construction time, speed is not always the key benefi t for customers. “For some customers, a predictable schedule is more important as they make plans for occupying the building.”

Of course, off-site manufacturing does increase speed of construction when large numbers of components are built in a factory. A 10-story building in the industrial town of Mohali, India holds the speed record for superstructure-plus assembly with the structural-steel subassemblies and other components, without interior fi nishes, completed in 48 hours.

In Los Angeles, a 102-unit apartment complex for the formerly homeless is entering the fi nal phase of construction with the modular units hoisted into place at a rate of six to eight units per day. The architect for the project estimates traditional construction timeframe of 18 to 22 months compared to the estimated 13 months projected for the modular construction.

Quality is another key benefi t of manufacturing components offsite, says Konchar. “We are meeting manufacturing standards in construction with the production of modular units,” he says. This high quality translates to cost savings. “For example, with fewer defects per million joints welded, a team avoids wasted time in chasing issues during fi nish work phases.” The controlled environment of a manufacturing plant lends itself to more thorough quality testing and traceability of  components that enables the team to correct problems before the unit or system arrives at the worksite. Getting it right the fi rst time saves all parties money and time.

Balfour Beatty has many projects in which the company is both the contractor and a partner with ongoing responsibilities for managing and maintaining a building, says Konchar. “Quality is very important to us and to customers who maintain their own building. If original construction is high quality, you have fewer maintenance issues.”

“Safety is perhaps the most important benefi t of off-site manufacturing,” says Konchar. Not only are employees working in a safe environment, with less risk of injury, but safety on the jobsite is improved. “We are looking closely at the impacts on safety such as less trades working on-site and how we eliminate risk,” he says. Not only are fewer people working in and around each other, but we see less debris or stored materials, less construction traffic, and safer installation practices being put into place. Moving components of the construction off-site not only improves safety for the contractors’ employees and supply chain partners but also for the general public. “We were building student housing on a site with space constraints and students walking by the construction site all day,” he says. “We did not have to take up space storing materials and the reduction in traffic improved the safety of people walking in the area.”

Off-site manufacturing can also play a role in bridge construction as Sundt Construction demonstrated with the replacement of a Fort Worth, Tex. bridge. The bridge’s 12 24-ft tall, 160-ft long concrete arches were built in a casting yard about three blocks from the bridge. “We were able to construct the arches in a controlled, safe environment that resulted in a quality product,”
says Hedlund. Because Sundt chose to manufacture the arches as opposed to hiring another company, there was a cost savings. “Our bid was still about 6 or 7 percent lower than the second bid and the customer felt our plan for off-site manufacture was better.”

There are a number of challenges contractors must overcome when introducing off-site manufacturing.

Perception of public
Unfortunately, when many people hear the term “modular construction,” they think of portable or temporary trailers or buildings. The growing body of information about the success of  manufactured building modules will help contractors educate customers. At the same time, people throughout the industry need to educate each other to explain the benefits of off-site construction.

Need for collaboration
One difference between the U.S. construction industry and the U.K. or European industries is the advanced integration of the different components of the construction process. “In other countries designers and architects think in terms of pre-fabrication early in the process,” explains Konchar.

“As design-build becomes more common and as builders are included in the planning process, here will be more opportunities to identify off-site manufacturing opportunities,” says Hedlund. “It’s important to make the decision to produce modules at the start of the project so the design is prepared with modularization in mind.”

As construction companies such as Sundt and Balfour Beatty incorporate more modular construction into projects, their knowledge base grows. Another effort to research off-site modular manufacturing in construction and identify proven best practices is underway with a study led by Ryan Smith, associate professor and director of the Integrated Technology in Architecture Center, an interdisciplinary research consortium at the University of Utah in Salt Lake City and author of Prefab Architecture: A Guide to Modular Design and Construction.

“Modular construction is more common in the U.K., where land prices have skyrocketed, labor costs have risen and the construction industry began shrinking sooner than the U.S. industry,” says Smith. Environmental requirements to reduce the carbon footprint of a project are not voluntary in the U.K. and European or Asian countries as they are in the U.S., so there was more impetus to utilize off-site manufacturing to reduce waste, he adds.

Smith’s study will include 18 off-site modular construction projects, comparing key performance indicators of the modular projects to traditional projects. Cost, schedule, scope, quality and risk for each project will be evaluated. Interviews with key stakeholders in the projects will also be conducted.

The goal is to describe best practices and provide builders with information that will help them make informed decisions about modular construction, says Smith. The two-year study will be completed and the report issued the first quarter of 2015, he says.

As one of the funding partners, AGC of America will make the research results available to members, says Michael F. Stark, CAE, senior director, Building Division of AGC. Although off-site modular construction may not be appropriate for all projects, the concept of collaborative planning at the beginning of the process is important. “Our members have to do more with less and we want to provide resources that help them identify best practices that can help them succeed.” ◆

1. The Encyclopedia of Chicago. Housing. Mail Order. http://www.encyclopedia.
chicagohistory.org/pages/611.html. Accessed December 2012.
2. The Steel Master Building System. Quonset FAQ’s. http://www.steelmasterusa.
com/quonset-faqs/. Accessed December 2012.
3. McGraw-Hill Construction. SmartMarket Report. Prefabrication and Modularization:
Increasing Productivity in the Construction Industry. 2011.