Although special codes for impact-resistant glazing, often called hurricane-resistant glazing, started in Dade County, Florida following Hurricane Andrew in 1992, they have spread throughout Florida and are moving north up the East Coast and west along the Gulf Coast. The devastating hurricanes of 2005, including Katrina and Rita, will no doubt push the need for these codes even further inland.

In response to the code requirements, much research and development of specialized hurricane-resistant products has been done by curtainwall, door, window and skylight manufacturers to meet these new code requirements.

The South Florida Building Code (SFBC) was the country’s first building code to mandate windborne debris protection for all new construction, and the Miami-Dade County Building Code Compliance Office (BCCO) also has issued stringent building codes for South Florida. The Southern Building Code Congress (SBCCI) has placed significant weight on the need for impact-resistant glazing in most of its coastal jurisdictions as well. And, of course, the insurance industry is making it a financial necessity for building owners to participate on a voluntary basis.

Preplanning and Partnering

A trend in hurricane-resistant glazing is that manufacturers are being asked to provide more information to architects. Areas of interest for many architects include code requirements, types of glass and their performance levels, door hardware types and limitations and anchorage requirements for various framing systems and substrates.

Manufacturers test their products through standardized test methods, which are established by the American National Standards Institute (ANSI), the American Society for Testing and Materials (ASTM) and the American Architectural Manufacturers Association (AAMA). Once defined performance characteristics are determined for a particular project, the architect can specify products through common guide specifications, which are provided by various sources. Both AIA and the Construction Specifications Institute (CSI) specification guides reference ANSI and AAMA guidelines.

Some of the local code jurisdictions require that the glazing be approved before the installation of the specific building project can begin, so even more emphasis is placed on preplanning during the submittal process. The procedures and processing time for obtaining a code approval, which involve more than a typical AAMA/ASTM mock-up approval, can prove to be a time-consuming and expensive process. 

The reliability of the framing system manufacturer to execute the code approval, as required by the contract documents, becomes critical to the successful completion of the project. 

Preplanning with code compliance offices and partnering with capable, reliable manufacturers, along with a reputable test laboratory, are three of the most important ingredients in the development of successful hurricane-resistant framing designs, whether curtainwalls, storefronts, windows, doors and skylights. Sometimes because the code protocols do not cover all aspects of the framing systems, resolving the unknowns in the design stage can save a lot of time and money. These unknowns could include thermal issues, for example, which might go beyond the hurricane-resistant codes. Other issues could be light transmittance and aesthetics. Another subject that might be addressed is substrates. Is the system being anchored to steel, concrete or wood?

In addition to working with the architect in the design stage, manufacturers are now using more unitized and preglazed systems. Unitized systems are shop-built units that can be stacked and anchored on the jobsite. Preglazed systems (which, of course, have the glass installed in the shop before being shipped to the jobsite) are beneficial because the silicone glazing is handled more easily than in the field. Dry-glazed systems (where the glass is held in place by gasket rather than silicone) also are popular for certain jobs because the silicone drying time is avoided.

New Research 

The 2004 hurricane season prompted the Protecting People First Foundation, an organization set up for the protection of people and property, to start Project Safe Windows, an engineering-based study regarding the impact of these devastating hurricanes on various window-protection technologies. The study, Finding the Breaking Point, found that protective glazing works, but that not all products are equally effective. 

The study is available at www.protectingpeople.org. The research involved site inspection of damaged properties, as well as interviews with property owners, building contractors and insurance adjustors.

Much of this study has to do with technologies developed to provide protection against flying glass and to protect glass windows from wind pressure and windborne debris. When glass is involved, the architect and engineer must consider factors such as light transmittance, thermal transmittance, aesthetics, design loads and assembly. Furthermore, there are a wide variety of window materials and assembly options available to them. 

If many scientists are correct, global warming is increasing the severity of hurricanes. Whether it’s global warming or just a cycle, recent hurricanes have been some of the strongest on record. Architects, manufacturers and contractors can look for more stringent codes in the future to protect life and property against these violent storms. 

Protective Glazing Standards and Specifications

For many years, the fenestration industry has cooperated with government organizations to establish standards that cover security and protective glazing. Currently there are several associations that set standards and develop certification programs for the fenestration industry. 

The Protective Glazing Council (PGC) represents manufacturers of protective glazing products and systems, suppliers to the manufacturers, consultants and testing organizations. This group supports both government and industry in the development of standards and specifications.

The American Architectural Manufacturers Association (AAMA) represents window, door and skylight manufacturers, component and supply manufacturers, as well as service and consulting companies. AAMA is a primary source of performance standards, product certification and educational programs for the fenestration industry.

The Glass Association of North American (GANA) represents the entire glass industry and is divided into six divisions, one of which is Building Envelope Contractors. GANA provides a forum for exchanging information and ideas. GANA’s technical committee is in charge of developing educational resources, informational bulletins, voluntary standards, product specifications, training and work with other industry groups.

Protective glazing standards and specifications that relate to impact-resistant, or hurricane-resistant, glazing include the American Society for Testing and Material (ASTM) International standards E 1886 Standard Test Method for Performance of Exterior Windows, Curtain Walls, Door and Storm Shutters Impacted by Missile(s) and Exposed to Cyclic Pressure Differentials and E 1996 Standard Specification for Performance of Exterior Windows, Curtainwalls, Doors and Storm Shutters Impacted by Windborne Debris in Hurricanes.

Glass Basics

Annealed glass is brittle and breakable, but is easy to cut. Tempered and heat-strengthened glass is less brittle, but cannot be cut. These types of glass can be up to two-to-four times stronger than annealed glass. If tempered glass is broken, it disintegrates into small fragments. For this reason, tempered glass is commonly used in swinging doors, sliding patio doors and storefront windows.

Laminated glass is used in most blast-resistant and hurricane-resistant glazing. This type of glass is composed of a glass “sandwich” of two bonded lites of glass with a plastic interlayer between them. Laminated glass may fracture, but fragments remain bonded to the interlayer and in place inside the window if properly glazed.

Insulating glass is made up to two lites of glass separated by a spacer around the perimeter, with a sealant plied to bond the plates to the spacer to form a sealed unit. Insulating glass is common in multi-story office buildings and is being used more often in residential construction. For hurricane protection, insulating glass provides the added benefit of placing two panes of glass, with the interior pane being laminated, between building occupants and exterior elements. Also, as hurricane-resistant code requirements move north, insulating glass is necessary to meet thermal requirements.

USG
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