Overlooking a section of the continuous Metalastic Expansion Joint Covers.

Atlantic Convention Center Hits The Jackpot With Unique Roof System

It would be, by anyone's standards, a massive structure-half-a-million contiguous feet of exhibit space-more exhibit space on one floor than any convention center from Atlanta to Boston.

And despite its location-Atlantic City, the home to numerous world class casinos-the City Fathers were not in a gambling mood when it came to specifying the materials for the roof and selecting suppliers and contractors. The project would ultimately require the coordination of hundreds of workers, and communications and logistics worthy of a military operation. Perhaps more impressive than the 22 acres of roofing was the amount of coordination and cooperation on the part of all involved to get the imposing job done.

The Best of the Best

The new Atlantic City Convention Center, combined with many new hotel rooms now under construction, the expansion of the Atlantic City International Airport, and the resort's history in the convention industry, position Atlantic City once again as a leading convention destination. "The interest in this building is tremendous," said Atlantic City Convention & Visitors Authority executive director Marshall Murdaugh.


Groundbreaking for the $260 million project was February, 1993 with the grand opening scheduled for May, 1997. The Philadelphia architectural engineering firm of C.B.T./S.S.VK. was awarded the contract for the Convention Center with William Cline assigned the challenging task of project architect. Hamada Roofing of Philadelphia was selected to install the 765,000 square feet of roof. GAF Materials Corporation (GAFMC) would supply the roofing materials. C.B.T./S.S.VK. also retained John Willers, P.E. of Raleigh, NC as roof consultant for the project.

The first order of business was to determine the type of roof system that would be installed. The roof would be a Class A, UL approved roofing system. Another consideration was the aesthetics of the roof. Facing a shoreline of highrise casinos and hotels, the roof would be visible from many of the City's 12,000 hotel rooms. The showcase the City Fathers envisioned demanded more than a simple black roof.

Pouring and leveling the lightweight Insulcel cellular concrete.

Specifying An Unusual System

The roofing system C.B.T./S.S.VK. recommended began with a lightweight insulating concrete poured over the steel deck. The material, called Insulcel® cellular concrete, offered several advantages. It could be poured quickly and slopped to the roof drains as it was setting up, thus eliminating layers of additional insulation to provide the roof taper. Also the weight savings reduced the amount of structural steel the structure required.

Because of their expertise in dealing with Insulcel, Miorelli-Kirlin, Inc., of Edgemont, PA was subcontracted to pour the cellular concrete. As if fast and less expensive weren't enough, GAFMC included Insulcel in its 20-year guarantee. This provided the City Fathers with all the reassurance they needed on this high profile, much publicized undertaking.

Insulcel is applied as a slurry of Portland cement, water, and a foaming agent, which is actually pumped through a 3" hose. Two-foot by four-foot panels of expanded polystyrene panel are used as the insulation material. As Jack Kirlin explained, the slurry is poured over the panels, which have 30 holes and 30 slots allowing the concrete to bond to the substrate. Miorelli-Kirlin, working with an 8 to 10 man crew at all times, laid and tapered the 765,000 square feet of Insulcel in 60 working days, none of which were rainy or below 40 degrees F. "Two-and-one-half inches of Insulcel is the industry standard," Kirlin said, "to create the required slope demanded anywhere from 2-1/2 to 6-1/2 inches of Insulcel."

Over top of the Insulcel concrete, Hamada Roofing laid a STRATAVENT® membrane from GAFMC. STRATAVENT is comprised of a moisture resistant and flame retardant glass base felt, asphalt coated, and surfaced with mineral granules. These granules, on the underside of the base sheet, provide positive vent paths for any trapped moisture that may cause blistering, buckling and crackling. STRATAVENT is mechanically fastened to the Insulcel with special GAFTITE® Base Sheet fasteners. STRATAVENT is installed to the top of the base flashing and is fastened but is not sealed to allow for perimeter venting.

The layer over the STRATAVENT was one ply of GAFMC RUBEROID® 20, which was put down using a felt laying machine, which unrolled the material into hot asphalt. The top ply was granule-surfaced RUBEROID Mop Plus FR, for a Class A, U.L. system. Alternating sections of white and buff colors were used to meet the aesthetic requirements. At the height of the roofing operation, Hamada Roofing had between 25 and 30 men and women working on the immense project.

Covering the Capsheet STRATAVENT a venting membrane, with RUBERROID 20, a glass reinforced modified bitumen membrane.

Roof Access Made Easy

Another consideration on this project was the number of structures on the roof and how to access them. There are approximately 45 20-ft by 40-ft air conditioner units (the size of a tractor trailer) and another 45 8-ft by 20-ft units, all of which are enclosed to give the roof an orderly appearance. In addition, there are over 100 exhaust fans and miles of parapets. The bottom line is a lot of flashing was used on the job.

In addition, the building management specified that all of the AC units had to be accessible by golf cart, due to the distances that had to be covered as well as the weight of replacement parts. This necessitated some special consideration for the walkpad material. GAFMC recommended that, in order to protect the roof system, an additional two plies of RUBEROID be set in hot asphalt. Black Granulated RUBEROID was chosen as the top layer to clearly delineate the walkpads.

Where the walkways crossed the 2foot high expansion joints, 20-ft. by 4foot steel bridges were constructed. Two additional precautions were taken here to protect the roof. The Insulcel cellular concrete was poured here to a level surface so that the bridge would lie level. The steel bridges were supported by structural supports through the roof system and properly flashed.

Speaking of expansion joints, there's close to 3 miles of them on the structure including a variety of curb to curb, curb to wall, and different size joint cover applications. Metalastic® Expansion Joint Covers (EJC) were chosen because of versatility, flexibility, and ease of installation. The style used has exposed stainless steel flanges. These provide extra durability in the harsh salt air environment, as well as meeting the architect's aesthetic demands. Metalastic is available in white or black - black was chosen for this roof as an architectural accent to set the expansion joints off from the white and buff roofs.

Metalastic EJC were provided in 50-foot long rolls for 10" wide and 100-foot rolls for 8" wide, which meant that 50 or 100 feet of expansion joint cover could be rolled out before a seam was required. To make the job even easier, GAFMC provided the GAFCart, a wheeled rig that carriers the Metalastic EJC roll, and that two men could roll ahead as they worked.

With remarkable coordination and cooperation among all the contractors, the project is moving smoothly towards on-time, on-budget completion. "Challenges that normally arise," said Hamada Roofing president, Zachary Hamada, "were magnified by the sheer scope of the project."

Overlooking the partially finished roof, the foreground shows the exposed lightweight concrete before installation of the membrane system.

Accessing sections of the roof being worked on and material handling offered new logistical problems. The Convention Center abuts the Atlantic City Rail Terminal, making it convenient for visitors along the Eastern Corridor, but eliminating roof access on that long side of the horizontal building. This necessitated some long hauls of roofing material.

GAFMC designed and fabricated pallets to size that could accommodate the roofing materials and fit the contractor's equipment. Cellular phones became the order of the day-locating someone on a roof over 6 football fields long and two fields wide could take hours-simply too long when problems arose and decisions had to be made.

When the new Atlantic City Convention Center is complete it will be a new, dominating presence on the City's skyline. The City Fathers will look back proudly on their good judgment in selecting the roofing applicators, design professionals and material suppliers. They did what they hope the millions of visitors and conventioneers won't do they didn't gamble - they only bet on a sure thing.