Hurricane-Resistant Fenestration Should Combat Both Wind And Debris

Proper specification and installation of windows, skylights, and related products protects facilities during extreme weather events.


https://facilityexecutive.com/2020/06/hurricane-resistant-fenestration-should-combat-both-wind-and-debris/
Proper specification and installation of windows, skylights, and related products protects facilities during extreme weather events.
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Hurricane-Resistant Fenestration Should Combat Both Wind And Debris

Proper specification and installation of windows, skylights, and related products protects facilities during extreme weather events.

Hurricane-Resistant Fenestration Should Combat Both Wind And Debris

By Jason Seals

The need for hurricane preparedness should never be underestimated. In 2017, the first instance of three Category 4 hurricanes hitting the U.S. in the same season occurred, causing approximately $265 billion in damage.

In the aftermath of this devastating storm season, teams of construction engineers under the direction of the National Science Foundation, the National Institute of Standards and Technology, the Federal Emergency Management Agency, and the American Society of Civil Engineers assessed the current building standards to see how they could be improved. The fenestration industry launched its own investigation into how damage to fenestration products (including windows, doors, curtain walls and storefronts) impacts the level of damage caused by hurricanes. Results from these assessments concluded that stronger building codes and better preparation greatly reduce the damage caused by major hurricanes.

hurricane-resistant
In 2018, a Category 5 Hurricane was responsible for heavy damage in Kowloon, Hong Kong. Seen here is a damage high-rise building.

According to former National Oceanic and Atmospheric Administration (NOAA) meteorologist professor David Dilley, of Global Weather Oscillations (GWO), the 2020-2021 hurricane season will be severe, with 11 hurricanes predicted, five of them major. Dr. Dilley led the team that launched the proprietary “ClimatePlus Technology,” which uses environmental cycles to predict hurricanes. The system considers influences like intermittent El Niño (area of warm water) and La Niña (area of cool water) presences in the Eastern Pacific, the Atlantic Ocean’s water temperature and 72-year climate pulse cycles to predict hurricane landfalls with a six-month lead time.

The approach taken by GWO successfully predicted all nine hurricane landfall locations between 2016 and 2019. They had 91% accuracy when predicting named storms in the 2019 season.

The 2020-2021 conditions indicate an active and potentially destructive season due to the warm ocean, lack of or very weak El Niño and the 72-year climate pulse, which all lead to a greater number of hurricane landfalls.

Of the coming season, Dr. Dilley said, “We are coming into a very bad cycle. What’s the bottom line? Don’t get caught by surprise. More of your industry’s [hurricane-resistant] products are needed.”

Evaluating Hurricane Resistance For Windows

The role of hurricane-resistant fenestration in preventing catastrophic damage to buildings cannot be overstated. These products must possess enough structural strength to resist extreme winds, impact from wind-borne debris and water penetration.

Current codes for buildings to resist damage due to wind pressure proved to be mostly adequate, preventing high-velocity winds from entering buildings and causing extreme structural damage. However, breakage caused by windborne debris appeared to be a greater concern, with the added risk of penetrations in the building envelope caused by debris leading to building collapse due to over-pressurization of the interior. The study showed that the building codes enforced at the time of the storm did not account for the size and speed of all possible debris. Additionally, in buildings with an otherwise intact building envelope, water penetration appeared to be the most damaging effect of a major storm.

How should adherence to industry standards for hurricane-resistant fenestration products be determined? They should be independently tested by an accredited third-party laboratory and certified by an accredited certification body. Hurricane resistance can be maximized by using impact-resistant windows and doors featuring impact-resistant glazing, a robust framing system and appropriate integration into the building envelope to resist structural loads and windborne debris, as well as water penetration.

Hurricane-resistant fenestration products are subject to testing in the laboratory under simulated storm conditions per Miami-Dade protocol TAS 201/202/203 or AAMA/WDMA/CSA 101/I.S.2/A440 and ASTM E1886/1996. To pass these tests, the product must meet the specified limits for air infiltration and structural performance, not allow water to penetrate through the product to the interior of the test chamber, and remain intact after 9,000 pressure cycles after withstanding impact from simulated windborne debris.

hurricane-resistant
This is an example of large missile impact testing of commercial glazing. The impact locations are visible on the product and the 2×4 missile is captured mid-flight. (Photo: Architectural Testing)

Features of impact-resistant fenestration include laminated glass with a heavy interlayer, often polyvinyl butyral (PVB) or polycarbonate, between two pieces of glass bonded by heat and pressure. Anchorage to the building is also critical for proper function, and additional fasteners often are used to secure the product to the rough opening and ensure maximum stability.

Proper installation is of the utmost importance. Even hurricane-resistant windows may leak if not properly flashed and sealed. To prevent water penetration, a robust integration of the fenestration product into the building envelope is necessary; the frame must join with the exterior sheathing and water-resistive barrier (WRB) to form an integrated drainage plane. Water that passes through exterior cladding does not penetrate the WRB and is sluiced down the inner cavity to the exterior.

Market research by the Fenestration and Glazing Industry Alliance (FGIA) has shown a shift in understanding of hurricane-resistant glazing versus other types of glazing in the industry. The market for non-residential hurricane-resistant glazing systems in the U.S. showed a steady 4% increase from 2017 to 2019 as the demand for non-residential impact-resistant products grew. Of the current non-residential applications, Florida comprises 91% of impact-resistant product usage.

Within the Florida market for hurricane-resistant glazing, 40% is comprised of non-impact glazing, compared to the larger section of the market at 60% for impact glazing. All other states predominantly chose non-impact glazing, with impact glazing making up less than 1% of the market.

Testing And Building Codes Protect Facilities And People

The assessments conducted in the aftermath of the unprecedented 2017-2018 hurricane season concluded that the stronger building codes developed in Florida following Hurricane Andrew in 1992 greatly reduced the level of destruction compared to other states. Newer buildings experienced less damage due to the installation of upgraded glazing systems, which provided the most resistance to wind pressure, water penetration and windborne debris. The greater percentage of impact-resistant hurricane windows installed in the Florida market due to these strengthened building codes, led to lower levels of devastation in the region.

The recognition of and need for hurricane-resistant fenestration appears to be on the rise as the ability to predict the severity of hurricane seasons becomes more accurate and the understanding of the necessity of hurricane-resistant products grows. The information gathered post-hurricane season has led to greater application of effective building codes resulting in less damage and devastation. The predicted severity of the 2020-2021 season could offer better insight into the success of these measures.

Seals is certification services manager, fenestration for the Fenestration and Glazing Industry Alliance (FGIA). He started his career with the association in 2014. He oversees all aspects of all AAMA Certification programs.

 

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