A new study sponsored by the Fire Safe Construction Advisory Council comparing construction costs among five building systems has found that a compartmentalized construction approach using concrete-based methods costs no more than other systems. The 800-page study offers alternatives for designers who shy away from fire-resistant design techniques due to perceptions of elevated cost and other issues.
The Intl. Building Code allows larger buildings to be constructed from wood when they incorporate active fire-protection systems such as sprinklers, explains James G. Toscas, president of the Precast/Prestressed Concrete Institute, Chicago. This has led designers to assume that wood provides a more economical approach than using passive fire-resistance construction techniques, such as compartmentalization and specifying fireproof materials. With no reliable documentation to support or refute this perception, the council decided to study the design options in detail.
The council’s report now has been released and is available through the Precast/Prestressed Concrete Institute’s northeast regional marketing office. The council is a consortium of four groups: The NE/NY Fire Safety Construction Advisory Council, the Pennsylvania Fire Safe Construction Advisory Council, the Mid-Atlantic Fire Safety Construction Council, and the NorthEast Cement Shippers Association.
The study evaluated the impact of building a fire-resistant multi-family residential structure using five different building techniques to meet requirements of the 2003 IBC. The five systems comprised:
- Conventional wood framing with a wood floor system using Type 5A or 5B construction.
- Light-gauge steel framing with a cast-in-place concrete floor system on a metal form deck.
- Load-bearing concrete masonry construction with a precast concrete plank floor system or a cast-in-place concrete floor system.
- Precast concrete walls with a precast concrete floor system.
- Insulated concrete form (ICF) walls or interior bearing walls made with concrete masonry units (CMU) with a precast concrete plank floor system or a cast-in-place concrete floor system.
The evaluated design featured four stories encompassing 25,000 square feet per floor. Two models were created, one with single-bedroom layouts and another with a mix of one- and two-bedroom layouts to “more realistically address the variety of construction configurations commonly found in the multi-family dwelling marketplace,” the report says.
The State College, PA-based team assembled to design these structures consisted of Haas Architects Engineers; Tim E. Knisely, a senior fire and commercial housing inspector for the Centre Region Code Administration; and Poole Anderson Construction, which provided cost estimates. The team chose three geographic locations in which to locate their projects (Framingham, MA; Harrisburg, PA; and Towson, MD) to examine the impact of diversity in labor and material costs.
The study’s consensus was that the costs associated with using a compartmentalized construction method that took advantage of precast concrete’s benefits required less than 2-percent more total construction cost. “Comparatively speaking, this is less than the contingency budget typically recommended for the owner to carry for unanticipated expenditures during the project,” the report notes.
In addition, although the precast option’s initial, in-ground cost was slightly higher, the standardized design that was studied could not fully leverage the advantages offered by a total-precast concrete solution, Toscas points out. The cost evaluation also could not take into consideration that precast’s longer spans and shorter construction schedule could provide substantial savings that might eliminate the cost differential entirely in the overall budget.
The report did note that the use of concrete materials can provide additional long-term benefits. “The minimal increase in construction cost can also help pay for itself over the life of the structure,” it says. “Materials like concrete masonry, precast concrete, and cast-in-place concrete have many other advantages beyond their inherent fire performance.” These include resistance to mold growth and damage from vandalism plus minimal damage caused by water and fire in the event of a fire.
“In many cases, with this type of construction, the damage outside of the fire compartment is minimal,” the report states. “This provides for reduced clean-up costs and quicker reoccupation of the structure.”
A copy of the full report, along with a summary of its conclusions, is available from the Precast/Prestressed Concrete Institute Northeast (www.pcine.org). Headquartered in Chicago with technical and marketing professionals, PCI is an association of more than 2,000 members, including 230 certified producers operating 320 plants and 100-plus supplier members. With more than 1,000 professional members (engineers, architects, and academicians), PCI is a dynamic force in the steady growth of the industry since its inception in the early 1950s. The organization is international in scope and influence. To find out more, visit (www.pci.org) or e-mail ([email protected]).