The architectural firm, A. Epstein & Sons International, actually specified the light-colored PVC membrane prior to the energy code going into effect in 1996.  The firm already was at the forefront of energy-conscious design.

Berger said they wanted a single ply roof application that could fulfill a variety of conditions in a modern design sense, which also maintained a low profile along the perimeter of the roof itself.  Other important factors in the selection of the membrane and manufacturer were having one source of supply for such a large quantity of roofing material and the manufacturer’s ability to get the material to the job.

Dave Trolian, the general superintendent for Clark-McHugh-Rausch, a Joint Venture, the Chicago-based general contractors for the project, felt this type of membrane provided a number of advantages as well.  Portions of the Midway Airport structures are being built while others are being torn down. Throughout the project, the airport remains open.  This creates some scheduling challenges.  Trolian said that because PVC is very durable, using it helped with scheduling since other contractors can work on top of it. If there are any penetrations, they can quickly identify and repair them as work continues. He also said it allowed for some very clean details.

“I’ve been on some of the largest projects in Chicago in the last 10 years,” Trolian said. “But I’ve never been on a project of this size with such few problems.”

The roofing installation, while challenging, did not present a problem to veteran roofing contractors, Roofs Inc. of Lyons, Illinois, a Chicago suburb. The project, which consists of the terminal, concourses and pedestrian bridges, provided a variety of conditions, with some roof surfaces being flat and others sloped. In some cases, the membrane was fully adhered over portions of the concrete deck. However, most of the deck is metal and most of the membrane is mechanically attached.

Some acoustic roof areas required the installation of 3-inch polyisocyanurate (psi 25) tapered insulation over the metal decks with the UltraGard PVC membrane mechanically attached over the insulation. On the concourses, the metal deck is fluted and exposed to view inside the terminal.  To provide the appropriate acoustic properties, wire screening and strips of fiberglass insulation were applied between the flutes on the exterior roof.  This was then covered with rigid insulation board before the membrane was installed.

According to Tom Elander, sales engineer for Roofs Inc., there were a number of unique details required on this project.  There was extensive use of JM Presto Lock® Fascia and Coping Systems, which are included in the warranty.  There also was extensive use of Expand-O-Flash™ expansion joints. The perimeters required an overlay of half-inch plywood over the insulation.  Because there was little or no parapet on the perimeter and the clearance was low, there was not much height clearance to accommodate the depth of the insulation.  Therefore, it was necessary to further taper the insulation.

The project also has 20,000 feet of linear walkways. The owner wanted a grey color for these walkways, which Johns Manville was able to accommodate.

The fact that this is an airport also presented its own set of challenges. Being located on a wide-open plain, wind uplift exposure was significant.  Therefore, the mechanically attached membrane had to meet an uplift FM 1-60 rating.  Because of jet engine dynamics, the building needed flexibility to move and vibrate, which was true for the roofing system as well. The normal detailing and the PVC system had the inherent characteristics to provide sufficient flexibility.

Not only has the airport remained open throughout the project, but also the work was underway on September 11.  This delayed the project for a month while safety and security concerns were addressed. Everyone agreed that the project has gone smoothly. Berger said there was not a single problem with a roof failure or leaking, or any deterioration in the course of the operation of the building. 

“This system has performed extremely well even as the building has been under continual construction,” he said. Berger also said that there was no problem in getting the roof system to marry when attaching it to an existing portion of the building. 

Trolian was very impressed with the professionalism of Roofs Inc. “Roofs Inc. was very diligent about reviewing potential damage from construction and made sure no cuts were overlooked,” he said.   “They always made us aware of any compromises.”

A senior Roofs Inc. team is involved with the project, including Joseph B. McDevitt, president.  Ted Hehn, the roofing foreman, ran the job and Richard Sterner, the roofing superintendent, has been involved throughout the 4-year project.

Roofs Inc., which has been in business for more than 30 years, specializes in single ply roofing.  They are Summit Club members of the Johns Manville Peak Advantage™ program, a distinction that only 10 percent of Johns Manville Peak Advantage members achieve.  The company likes taking on challenging projects with a constant focus on safety, which is headed by its safety director, Paul Prost.  In addition to Prost, Roofs Inc. also engages an outside firm to help monitor safety.

Johns Manville, a Berkshire Hathaway company, is a leading manufacturer and marketer of premium-quality building and specialty products.  In business since 1858, the Denver-based company has sales in excess of $2 billion and holds leadership positions in all of the key markets that it serves.  Johns Manville employs about 9,000 people and operates 43 manufacturing facilities in North America, Europe and China.  Additional information can be found at www.jm.com.