FIVE STORIES OF WOOD OVER CONCRETE SLAB

Project: Advanced Individual Training Barracks with Company Operations
Location: Fort Lee, Virginia
Architect/design-build: LS3P ASSOCIATES LTD. and Clark Builders Group
Structural engineer: Michael M. Simpson & Associates, Inc.
Size: 360,000 square feet
Type of construction: Type IIIA wood-frame construction on concrete mat slab
Year of completion: 2011

LS3P ASSOCIATES LTD. and Clark Builders Group designed and constructed the design-build Advanced Individual Training Barracks with Company Operations in Fort Lee, Virginia, as the seed project under a Multiple Award Task Order Contract (MATOC) for the U.S. Army Corps of Engineers. The $68,169,000 LEED Silver project consists of two five-story barracks situated on an 11-acre site. Each 180,000-square-foot building has 600 beds and meets IBC 2006, NFPA 101 egress and life safety provisions, plus Anti-Terrorism/Force Protection Criteria. Set on a reinforced concrete mat slab, the buildings are clad primarily in brick.

“The team provided three structural options: cast-in-place concrete, light-gauge steel framing and panelized wood stud framing,” recalls Chris Ions, AIA, LEED AP, vice president/principal of LS3P ASSOCIATES LTD. “The steel came in $2 million cheaper than the cast-in-place concrete and the wood came in $2 million cheaper than the steel, a significant difference.” The advantage of working as a design-build team was being able to explore a number of framing choices to determine which was the most cost efficient.

To minimize the impact of shrinkage, the walls are balloon-framed with flooring rim beams on the inside, rather than on top of the top plates (platform framing) at each floor of vertical framing. The first floor has the heaviest framing with triple studs of southern yellow pine, selected for its high compression strength.

The first three stories of brick veneer were supported on the foundation; steel relieving angles through-bolted to the wood framing were used to support brick at the fourth and fifth floor levels. “The greatest challenge of wood construction is looking at every assembly, transition and penetration to ensure that fire-rated assemblies are truly continuous,” says Ions.

FIRE SAFETY DURING CONSTRUCTION

Although less than 2 percent of building fires occur during construction, this phase presents unique risk scenarios that make any building more vulnerable regardless of material.

IBC Chapter 33 provides minimum safety precautions for fire during construction and the protection of adjacent public and private properties. The section includes provisions for fire extinguishers, standpipes, means of egress and sprinkler system commissioning. The International Fire Code also contains detailed requirements.

The most common causes of fire in wood buildings under construction are arson and hot work, making site security, rigorous procedures for workers and access to fire hydrants a must. Education is also important, since fires that occur during this phase are also caused when required elements—such as fire doors, smoke alarms and sprinklers—have not been put in place.