Volume 13, Issue 6 - July/August 2012


Tornado-Resistant Products Develop as a Niche
by Megan Headley

The National Oceanic and Atmospheric Administration noted in its 2012 State of the Climate report on tornadoes that the U.S. spring and summer of 2011 will likely be remembered as one of the most destructive and deadly tornado seasons to ever impact the nation. Yet few fenestration companies are finding themselves shipping their impact products to meet a new demand for tornado-resistance.

Certainly tornadoes are getting some notice from code officials. On April 16, 2002, the International Code Council (ICC) announced that it was extending its support to communities affected by severe weather, including the more than 100 tornadoes in the Plains region, with its Disaster Response Network. The database lists volunteers available to assist with building damage assessment, inspections and other code-related functions. But ICC isn’t yet seeing additional adoption of its ICC 500, Standard for the Design and Construction of Storm Shelters, according to code watchers.

When it comes to windows, structures in tornado zones just aren’t yet getting the beyond-code protection that has become more common in hurricane zones.

Dr. Pat Condon, owner of West Tampa Glass in Tampa, Fla., isn’t expecting that to change anytime soon. “As far as I know, the shelter code, ICC500-08 is only approved in Alabama for schools and in Florida for community shelters,” Condon says. “This code incorporates tornado-resistant glazing but is limited to community shelters. ASCE 7-10 and IBC-12 have not introduced any tornado code for non-shelters. Therefore, Risk IV facilities can still be built without impact glazing; even though they are operational during the storm, same as shelters.”

Condon adds, “I do not believe tornado-resistant glazing will advance far until the building code requires it.”

David Barnes, president of ViWinCo in Morgantown, Pa., ships impact windows to hurricane regions along the East Coast, “so I would say that I’m not in the tornado prone areas, so to speak… but it seems to be the [entire] United States now is tornado prone,” he adds. “Our product meets all the impact requirements as far as hurricanes, but I don’t really see a lot of people calling us about impact windows for tornado areas. Obviously, to keep the building intact is what the impact windows are all about, but with tornadoes throwing up to 200 mph winds, usually the impact [windows] only go up to that 170 mph sustained wind requirement.”

As far as a tornado product, Barnes says, “Nobody’s really coming after us looking for it.”

Some experts have heard a smattering of interest in tornado-rated fenestrations and have begun selling their impact products to this region.

“There are definitely a handful of players who are aggressively developing window products to meet the requirements of ICC 500,” says Vinu Abraham, vice president, Southeast region for Architectural Testing Inc. in Riviera Beach, Fla. “I know of at least two that have been successfully passed test requirements. There are several others that are actively trying to develop it. It’s a pretty tough challenge to try to solve,” Abraham adds.

Companies such as Insulgard Security Products are responding to a roused interest for these types of products.

“We haven’t seen any new state mandates but we have seen an increased interest in the FEMA-tested windows for community shelters and safe rooms throughout the Midwest,” says Gerry Sagerman, business development manager for Insulgard.

“With the increase in tornadoes and the bad weather and everything going on in the Midwest, we’ve seen an increase in [interest from] a number of schools and community shelters. I don’t know if it’s that the product is getting out there and people are more aware of it, but we definitely have seen an increase in both the hurricane and really the tornado glazing,” he says. “We’ve even had individuals contact us when they’re looking at putting in a safe room, asking, ‘Are windows available?’”

With the lack of state mandated “incentive,” many manufacturers feel there is still some confusion regarding what constitutes a tornado-rated glazing product. Sagerman adds that confusion on this point is found among design professionals, as well as within the glass and fenestration industries.

“What we still see is a real confusion and maybe not an awareness of what the requirements are for some of these windows, and the requirements for testing. From architects to building owners, just not really knowing what testing needs to be on these windows and so there’s still a little bit of confusion out there as to what needs to be tested. To be honest, there are products that don’t meet all of the requirements of the testing. That’s something we still struggle with as an industry,” he says.

In response to this confusion, the American Architectural Manufacturers Association (AAMA), in collaboration with the National Institute of Building Sciences’ Building Enclosure Technology and Environmental Council, published AAMA 512-11, Voluntary Specifications for Tornado Hazard Mitigating Fenestration Products in 2011. The document provides a system for testing and rating the ability of windows and their anchorage to withstand extreme windloading, debris impact and water penetration typical of tornadoes. Although AAMA 512 drew from the testing parameters, protection levels and geographical wind zones described by ICC 500 and FEMA 361 tornado wind zone charts, it is applicable to the fenestration of any building for which maximum practical tornado protective design is specified.

“There have been no specific questions regarding the document. However, we’ve sold several copies of the document and several of our members are already putting it to use within their own product lines,” says Ken Brenden, AAMA technical services manager.

“We fully expect that awareness and the market will increase as more manufacturers expand their product lines to include options for tornado hazard mitigating framing systems,” Brenden adds.

As AAMA’s specification points out, an EF-4 or EF-5 tornado has the potential to level an entire building, making little difference as to how well its windows perform. However, hazard mitigation opportunities do exist for buildings exposed to the most common tornadoes.

At this point, experts agree that educating the owners and managers of essential facilities as to the tools available to help them build to a higher level of quality is a critical component of advancing tornado-resistant glazing.

As Barnes says, “If I were putting [windows] in my house, they would definitely be impact for a number of reasons.”

Megan Headley is special projects editor for DWM Magazine.


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