Sundeck roof dangerous
A decision to use a copper roof on the reconstructed Sundeck Restaurant last year has proven costly and potentially dangerous for the Aspen Skiing Co.
The Skico, its architect and contractor scrambled this summer to try to solve two problems on the roof – snowslides and the build-up of ice dams. The ice dams threatened the structural integrity of the edge of the roof; the snowslides threatened the safety of Sundeck customers.
“When you build a building of that scale, at
that kind of site, on that time line, there are several things that aren’t anticipated,” said Susan Touchette, an associate at Cottle, Graybeal, Yaw Architects and project architect on the $14 million Sundeck.
The performance of the roof is biggest among those unanticipated items. The roof was designed to hold rather than shed snow to convey the feeling of a European mountain refuge – cold and snowy on the outside, warm and inviting on the inside.
To hold the snow but avoid the build-up of ice dams, the Sundeck has a super-insulated roof to prevent the transfer of heat. A small amount of heat is somehow getting lost, causing snow to melt and water to trickle down to the edge of the roof. The freeze-and-thaw cycles created ice dams of up to a foot thick last season, said Touchette.
The weight of the ice could have created problems for the edge of the roof, although the overall roof wasn’t threatened with collapse, she said. Skico wanted copper The snowslides are an unrelated problem. Touchette said her firm’s original design proposed use of corten steel as the main material on the roof. That’s a steel alloy that quickly rusts and creates an appearance that many local architects feel meshes with Aspen’s mining history.
Since the roofing material plays such a critical role in the building’s appearance, the Skico’s ownership and management spent a great deal of time debating what looked best, said Touchette.
“The Ski Company asked us to consider other materials,” she said. The decision to go with copper was made “right before construction. It was an important decision that was not made in the proper design sequence.”
As it turns out, it might have been the wrong decision. Copper has a lower coefficient of drag than corten steel. Therefore, the snow starts sliding more readily than anticipated, said Touchette. However, she said she couldn’t say with certainty whether corten steel would have completely eliminated the snowslide problems. `Spiffed-up heating tape’ To solve the problem of the ice dams, the Skico has installed a Bylin heating system along the entire length of the eaves and up the main roof for 10 to 15 feet on either side of the main entrance on the eastern side of the building – facing the Silver Queen Gondola.
“It’s basically a spiffed-up heat-taping system,” said Touchette. Evidence of the heating system can only be spotted upon close examination. Most of the system is underneath the copper.
While that eliminated the ice dams and the threat of ice on the roof’s edge, it did little to solve snow sliding on the east or west sides of the roof.
The Skico has created a no-man’s land on the ground beneath the east side of the roof by using chains to prevent people from entering. The ski racks have been moved away from the building, creating a slight inconvenience with their perch on a slight slope. Blue spruces were planted last summer to further offset the forbidden zone.
It’s an unfortunate but wise business decision on the part of the Skico, said Touchette.
“Since the snow slid several times last season, there’s potential for that to happen again,” she said. “It could take a few years before they consider the situation 100 percent safe.” No cheap remedies An immediate solution was needed to deal with slides on the west side of the building. Although snow fences were part of the roof design on that side of the building, a small amount of snow was still sliding onto the decks below, according to Eric Calderon, who oversees the Sundeck.
Two snow fences were part of the west roof design. The roof was built after considerable engineering to anticipate snow loading.
A third snow fence was added by contractor Shaw Construction last summer to prevent snow that was sliding through gaps underneath the two previous sets, said Calderon.
The solution for the east side isn’t as simple as installing snow fences or replacing the copper with asphalt shingles.
The east side of the roof wasn’t engineered with snow fences in mind. “We would have to remove the entire roof and start from scratch,” said Touchette.
And while the slope of the roof is steep enough to send snow sliding down copper, it may not be steep enough to shed water off asphalt shingles, said Touchette. Retrofitting the roof with shingles would require extra water barriers.
Neither solution is cheap, so for now the Skico will live with a situation where its restaurant is one of the biggest avalanche threats on the mountain.
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