- By Thomas C. Dolan
- April 1st, 2006
There is a growing trend among many school districts to opt for modular construction, both temporary and permanent, in lieu of traditional site-built schools. There is, in general, an increased demand for these options throughout the country, but especially in the southern belt, from Georgia and Florida to California, says Michele Cunningham, vice president of Marketing and Business Development of Baltimore-based Williams Scotsman. Modular activity is prevalent, especially in the south, Cunningham says, due to the combination of rapid demographic growth and legislation in many states for classroom size reduc¬tion to increase teacher/student ratios to improve educa¬tional outcome.
Portable classrooms work for school systems that are either going through renovations or population volatility where they may want one at the elementary school one year and the middle school down the street the next, Cunningham says.Portables allow for this flexibility. They are certainly less expensive and available in a much quicker time period than other types of construction. When our customers call in late spring or during the summer, having just realized they need facilities for a 100 more kids in the fall, there’ s no way a traditional construction initiative could meet that deadline.
These relocatable classrooms have been around for more than 30 years, Cunningham continues. They came into vogue when the kids of the baby boomers came of age and were en¬visioned as an adjunct to traditional facilities to compen¬sate for this demographic blip. There has been continual product development and improvements in terms of the manu¬facturing, distribution and service of these units.
An important thing to remember is that portables are built with the same raw materials, and subject to the same building and occupancy codes as site-built facilities, Cunning¬ham says.
Moreover, new on the horizon, she adds, are initiatives from Leadership In Energy And Environment Design (LEED) and Collaboration for High Performing Schools (CHPS) in California that envision establishing new and higher thresholds. These would include better site placements, use of sustainable materials, light and atmosphere controls, and better energy efficiency. Though these initiatives are currently in the early states of review and adoption, they appear to be a part of the wave of the future. I recently came back from the annual convention of the Modular Build¬ing Institute, and these initiatives were a very hot topic, Cunningham says. The modular building community is interested in working with officials to raise the bar on learning environments for our children.
The portable buildings are designed and intended for a 20-year use, says Cunningham. The permanent modular buildings, how¬ever, are meant to have the same life cycle as traditional site buildings — from 20 to 100 years. There are so many differing factors, in terms of design, size, maintenance and so on, that a more specific estimate is not practical, she says.
The permanent modular buildings are a more recent phenomenon, explains Cunningham. They’ve come into existence during the past 15 years. There have been some technical challenges that needed to be worked out, and adaptations have varied due to the geography of the area, she says. They’ve been more widely adopted in the wide open spaces, such as Florida and Texas, and less so in the more developed areas of the northeast.
These structures can be used in different ways. We recently finished a project in New Jersey that was a combination of renovation and adaptive use of the existing site buildings with modular additions, Cunningham says. But entire projects are also designed in modular from inception, with different phases to be put into place through time. A key reason for the increased demand for permanent modular, Cunningham says, is that schools work under a very narrow window of optimum building activity, so you want to minimize disruption to operations. When you’re able to build a permanent multistory modular structure in three months, as opposed to six months or a much longer time period needed for traditional construction, the shortened time frame can play an important role in the cost profile of a project.
Permanent Doesn’t Mean Limited
One type of permanent modular construction is called precast. The term precast, explains Corey Greika, sales engineer for the Atlanta -based Tindall Corporation, a manufacturer that specializes in this construction, refers to a kit of components for either school additions or new schools that is made off-site and shipped to the school site to be put together. The advantages over traditional construction, he maintains, are the speed of construction, the quality and durability of the material and the fact that you don’t give up any aesthetic values.
Greika says quality is better than conventional construction because the pre-made aspect of the components reduces the number of joints and minimizes air cavities so you don’t have mold issues. He explains that a typical exterior wall involves a 16-in. brick wall consisting of an inside concrete masonry wall, with an air gap that is then filled with insulation, and the exterior brick wall. Greika says that in the precast version this is replaced with an eight-in. precast wall panel in which the insulation is already encapsulated.
Greika adds that this is a significantly quicker construction schedule. For example, when erecting a two-story building, 150 linear ft. of this eight-in. wall can be put up in a single day, compared to two weeks for the typical masonry wall and two weeks for the brick exterior — a total of four weeks. That’s a lot of time and labor.
Traditional floors are made with metal decking and joist construction. Tindall uses a double-tee or four-plank process. The time factor is equivalent in both types, but the fire rating has already been incorporated into precast, while that’s a separate process for the conventional methods.
The interior standard masonry block walls are replaced by the eight-in. precast walls, which take one day, as opposed to two weeks, to install. The time to install interior ceilings is basically the same in either conventional or precast. Floor systems tend to match the roofs. The precast concrete roof will have fewer joints and will withstand 5,000 lbs. per sq. in. Precast roofs will have far fewer maintenance considerations, Greika says.
Precast combines many trades into one, he adds. One of the reasons this option came about was the lack of qualified masons who could deliver the quality. Even the ones who can can’t match the speed. Greika says the speed factor means cost benefits are seen the day the school opens.
Mansfield,Texas-based Ramtech Build¬ing Systems, Inc., is one of the companies that offers a variation of modular permanent, explains Ramtech President Mike Slataper. The ‘building kit’ aspect of precast gives the impression that it can be disassembled and relocated else¬where, though usually there wouldn’t be a reason for doing so. Ramtech designs buildings with modular concrete slabs that are heavier than the precast ones and, once installed, are totally permanent. Moreover, says Slataper, precast does involve some on-site work, such as electrical, air conditioning and finishings, but all these elements are included in his walls, which are totally put together at the factory.
There is a significant reduction in design and construction fees compared to site construction, but one of the biggest appeals to schools is that these buildings go up in a fraction of the time, Slataper says, a few months as compared to a year to 18 months.
Slataper reports that he focuses on eight states in the southeast, mostly rural districts. ‘We have our niche and don’t get involved with a lot of the big school districts in the cities. These urban districts often stick with traditional methods due to institutional habit, working with the same architects, perhaps with access to more money and other factors, such as a desire for high ceilings, which modular typically doesn’t provide.
We might build an entire school and do the cafeteria and gymnasium in conventional fashion, because it’s not cost effective to do high ceilings in modular fashion, Slataper says. But then we’ll make the classrooms modular.
Slataper’s company also does site construction and portable, sometimes simply leasing the latter. Because we are involved in all three types of construction, we have a pretty good handle on costs, Slataper says. In this part of the country, a temporary classroom building runs about $25 to $30 per sq. ft., a permanent modular costs about $75 to $85 per sq. ft. and a site-built facility $105 to $125 per sq. ft.
So, modular school construction comes in a variety of packages. Which package would be best for your district will depend on the needs of each individual project.