Safety behind the glass curtain
In Florida, Enclos Corp., a Minneapolis-based manufacturer of custom-designed curtain wall systems, offers an NOA-approved curtain wall. While Miami–Dade County only requires large-missile impact glass on the first 30 feet of building height in hurricane zones, some building owners choose to install the stronger glass over the full building height for added protection.
Such was the case at 1450 Brickell, a 35-story office tower in downtown Miami. The entire building is wrapped in a curtain wall system using large-missile impact glass, and arguably may be the strongest curtain wall in any commercial building in the U.S., says Adam Peine, general manager of sales and operations for Enclos. It was designed for very high wind loads: 185 lb/sf, compared to 130 lb/sf for a standard curtain wall. “In the event of a major hurricane, there will be less broken glass, less penetration of water and debris, and less cleanup,” at 1450 Brickell, says Peine. “The tenants can be back to work the next day.”
The curtain wall for 1450 Brickell did come with a cost premium. Peine says the cost differential for large-missile impact glass over small-missile impact glass is in the 10-15% range. That’s because custom curtain walls require testing, custom dies, heavier metal components, and additional engineering. Buildings located further inland can utilize Enclos’s standard NOA-approved system, which is pretested to 130 lb/sf. Peine cautions, however, that “standard, NOA-approved products can be economical solutions, but they are limited in application to the design parameters they have been tested to. Custom solutions can be fine-tuned to exact project requirements, and then tested to obtain NOA approval—a more practical strategy for high-rise buildings in coastal zones.”
One further piece of advice from Peine: When selecting a curtain wall for a project in a hurricane zone, Building Teams should look for a unitized, pressure-equalized system that is delivered to the site already caulked and glazed. This will minimize the amount of time spent in the field assembling the system.