Balcony railings made of a safer, laminated glass and framed in stainless steel are expected to be installed soon at the W Austin Hotel and Residences, the building's developer told the American-Statesman on Thursday.
Nearly 1,000 glass panels were removed from the 37-story building last week after a total of eight panels fell on three separate occasions in less than a month. The panels were made of tempered glass with exposed edges, secured by a pair of brackets on each side.
With temporary wood panels now in place on all the building's balconies, the hotel anticipates reopening its restaurant and bars Saturday, pending a city review, followed by guest rooms on Sunday or Monday, said its developer, Stratus Properties.
Engineers from two firms are scheduled to finish their inspections of the temporary panels by this afternoon, and a city inspector is performing spot checks.
But the new laminated glass panels, which Stratus CEO Beau Armstrong said could cost twice as much as the tempered ones, cannot be installed until investigators determine what caused glass to rain down from the building last month.
"They just don't know yet," Armstrong said. "Heat may have played a role. Wind may have played a role. Design may have played a role."
As the American-Statesman reported Sunday, glass experts consider laminated glass, which is considerably more expensive, to be safer than the tempered glass originally used in the W's railing systems. Laminated glass contains an inner layer of polyvinyl resin that keeps panels together when they shatter, preventing shards of glass from falling.
According to construction experts, the latest version of the international building code requires glass railings to be made of laminated glass if they don't have a protective top rail or frame.
The tempered glass railings on the balconies at the W, which lacked metal frames, were built under an earlier version of the code that many designers and builders interpreted as not requiring laminated glass. However, some cities in earthquake or hurricane zones, such as Miami, have prohibited tempered glass from high-rise buildings.
Though city officials have not signaled a move to prohibit tempered glass, which makes up the vast majority of exterior architectural glass in American cities, the incident at the W could spark a change in building practices in Austin.
Dan McNabb, division manager for building inspections, said the city planning department would "most likely" begin requiring special inspections of railing systems that use glass, such as the one at the W and several other downtown high-rises. Regardless, the city will require an engineering inspection for replacement railings at the W after they're in place, McNabb said.
A specific glass railing inspection is not spelled out in the international building code — the basis of Austin's code — but the code does allow local building officials to require any inspections they deem necessary for public safety. Such inspections, by outside consultants hired by the developer, are required for some other structural elements, such as concrete and welding.
Armstrong said it made sense to replace the railings with laminated, framed glass.
"That one really is the most conservative, so that's what we are going to do," he said. "It will be the same aesthetic, the same look, but just with a different frame and a little bit different design."
Engineers also inspected the concrete slabs of the balconies after they learned that an interior cable of strengthened steel, called a tendon, failed near the first glass railing that fell June 10. A Curtainwall Design Consulting report concluded that concrete and grout from near the failed tendon may have fallen on the exposed top edge of a glass railing, causing it to shatter.
The report recommended a survey of other slab edges "to determine if other damage or potential debris is present which may pose a risk for additional breakage."
On Thursday, Armstrong said that it wasn't yet clear why the tendon on the 27th floor failed but that subsequent inspections did not reveal any more problems with failed tendons. McNabb said he wasn't aware of any other incidents of tendon failure at the W.
"We've inspected every balcony since then and have not seen another incidence of a failed (post-tensioned) cable," Armstrong said. "In my opinion, we really know it's the railing system. It has nothing to do with the failed PT cable."