Vinyl Tops Canada’s Busiest Airport

Architects challenged with covering a 320,000-square-foot, vaulted U-shaped roof at Canada’s busiest airport turned to the one material with the flexibility, durability, aesthetic quality and fire resistance standards needed – vinyl.

In the $4.4 billion redevelopment of Toronto’s Pearson International Airport, the project specifications for the new terminal design were based on vinyl from the start, said Bruce Merstorf, vice president of sales and estimating at Bothwell-Accurate Co. Ltd. (www.baroof.com), a Toronto roofing and sheet metal contractor.

“Vinyl suited the barrel-like, curved roof design that the architects had,” Merstorf said. “Not too many materials can do that.”
The durability and reliability of the 1.5-millimeter thick, single-ply vinyl roof membrane will serve the state-of-the-art terminal well at Pearson International Airport. An average of 28 million airline passengers pass through annually, and that volume is expected to grow to 50 million passengers by 2020.

Three architectural firms worked together on the terminal project – Skidmore, Owings & Merrill International Ltd. (www.som.com); Moshe Safdie & Associates (www.msafdie.com); and Adamson Associates (www.adamson-associates.com). Aside from all the functionality they needed from a roofing material, they wanted one that would give them the clean, modern aesthetic desired. It also had to provide a surface that would minimize, if not eliminate, any glare for pilots during their final approach.

“We needed a smooth material that, from a distance, would create an impression of an immaculate thin gray slab segmented by ribbons of skylights – and yet be flexible enough to follow the integrated parapets and gutters in the roof lines,” said Rainer Goeller, principal architect of Moshe Safdie & Associates in Somerville, Mass.

Goeller led a four-person team working on the terminal roof project, and architects paid particular attention to the detailing of the roofline at the perimeter of the terminal building. The layers of the 2.5-meter deep roof assembly include roof sheathing on steel deck on trusses and beams. Despite the depth of the roof structure, however, designers succeeded in creating an elegant and subtle-looking overhang.

Set back from the upper gray sheet, the lower layer features white metal panels that match the interior metal ceiling. The effect is impressive: Travelers approaching the terminal by car notice the building’s elegant glass end gable with the layered bold roof overhang and the curved glass façade above the entrances to the Departure Level.

“Vinyl goes everywhere on the roof – vertically and horizontally,” added Goeller.

The vinyl membrane, which was manufactured by Massachusetts-based high-tech plastic polymer maker Sarnafil (www.sarnafilus.com), was bonded to the vapor retarder at the roof perimeter and at all penetrations in order to create a tightly-sealed airspace between the two layers. This helps prevent moisture ingress into the envelope between the vapor retarder and the loosely laid membrane whenever the membrane moves due to the action of wind forces.

This method also prevents air infiltration and exfiltration, and helps reduce possible leaks at necessary penetrations in the roof assembly. The roof membrane can move up and down even with strong wind gusts without affecting the integrity of the vapor retarder.

“Vinyl lies flat, is very pliable, and is great for any shape and contour design,” said Brian Jamison, operations manager of production for Bothwell-Accurate.