Four acre roof along Atlantic City boardwalk will soon receive stainless-steel sheathing.

Designing Against Salt, Seagulls And Weather

Strong coastal winds, salt air and seagulls were among the factors considered by the designer of a $1million-plus stainless-steel replacement roof. The sheathing will be installed on the four-acre, barrel-shaped roof of the main hall at Atlantic City's 63-year old convention center.

"We wanted a material that would survive for 30 years or more" without leaks in the New Jersey city's hurricane-prone, oceanfront locale, says John Willers, director of roof engineering services at Raleigh, N.C.-based SM&E Inc. SM&E was known until this month as Westinghouse Environmental & Geotechnical Services Inc.

While the local building code requires roofs to withstand only the 85 mph winds expected in a 50-year storm, the convention center and SM&E decided it would be prudent to design the replacement roof to stand up to the 105-mph winds expected in a 100-year storm.

As for the seagulls, Willers says they crack open shellfish on the roof and "broken shells tend to accumulate." Maintenance workers on the roof tend to walk on the shells and the sharp edges tear all but the toughest of roof materials.

Declining to compare costs, Willers says that other roof types would be "workable" but not as ideal. For example, 40-deg slopes would have made it difficult to install hot asphalt for a built-up roof. Also, the stainless roof's 30-year warranty against leakage and uplift was the best offered. That was important because of problems with the current 10-year-old membrane roof, says Joseph M. Dolan, convention center director of facilities and operations.

The project, going out for bid in a few weeks, will be completed late this year. First, workers will remove the old roof. The new roof, which will bear on a previously installed built-up roof, will consist of three 1/16-in.-thick (ASTM 316) sheets of stainless steel atop a rosin paper slip sheet, a synthetic rubber membrane and an ice shield adhered to a strand type of particle board.

The new roofing system has joints between the metal panels, "because of temperature changes and because there are no expansion joints in the barrel of the roof itself," say Willers. He adds that the 4-ft-wide, 12.5-ft-long panels are "interlocked" with fasteners that "allow some movement" without undue stress.