Volume 36, Issue 2, February 2001
Understanding Impact-Resistant Building Code Changes
The requirement for impact-resistant glazing systems continues to grow as new
building codes recognize the important role glazing systems play in protecting the
structural integrity of a building during a major storm. Studies conducted after Hurricane
Andrew revealed that buildings stood a much better chance of surviving a storm if the
glazing material remained intact and in the framing system. South Florida responded to
these studies by establishing the South Florida Building Code (SFBC), which requires
glazing systems to undergo rigorous testing and certification. The code requires that
glazing systems located up to 30-feet above the ground be capable of withstanding the
impact from large flying debris, and the areas above 30-feet be able to withstand the
impact from smaller debris that might be lifted up by storm winds. The testing includes
impacting both the aluminum framing system and the glass, and then subjecting the entire
system to a cycle test that is designed to mimic the buffeting winds of a hurricane. To
pass these tests, the glass must remain in the framing system and not permit any
significant openings through which wind and water can pass.
The intent of this new code was to encourage manufacturers to develop glazing systems that
did not require storm shutters, yet would provide the desired protection from major
storms. A few manufacturers responded to this challenge and developed entirely new systems
that enabled architects to meet the new codes and still utilize large expanses of glass in
their designs. The new Florida State Building Code and the International Building Code
have accepted the wisdom of the SFBC to require passive impact-resistant
So, How Do the New Building Codes Affect You?
Providing full time protection to buildings from flying debris associated with hurricanes
results in additional costs for glass and glazing installations. The aluminum system
itself must be able to absorb the impact of projectiles and provide glazing details
designed to keep the glass in place. These requirements result in aluminum systems that
are wider to provide sufficient glass bite, and deeper to meet the structural requirements
of the increased design loads, as well as the actual impact. The cost of the glazing
material has also increased dramatically, as new materials were developed that would
survive the impact and subsequent cycling. Several new laminated products and composites
are available, but their cost per square-foot may be as much as ten times greater than
conventional glazing materials. In addition, the cost to fabricate and install these new
impact-resistant systems is also greater.
The additional cost of supplying and installing impact-resistant glazing systems does not
end with the increases in the cost of the material and labor. The cost to provide
submittals for a project will also increase. Explicit anchoring details and schedules must
be included with your shop drawings. The shop drawings may also have to be reviewed and
approved (stamped) by an independent licensed engineer resulting in increased cost and
lead time. Copies of certified test reports will have to be submitted to demonstrate that
the glazing system, the combination of glass and the aluminum systems, have been tested
and will meet the code requirements.
So What Do You Need To Do?
Start by learning more about your local building codes. Codes are changing rapidly and
failure to stay abreast of the code requirements may result in a serious financial loss.
Even if you do not live or work in coastal areas, local building codes are changing to
address inherent shortcomings in structural requirements. For all projects, especially
those along the coastline, be sure to review the project specifications carefully. Review
the installation instructions from your metal supplier and make sure that all of your
personnel understand how to estimate, fabricate and install each system. Monitor field
crews to ensure that they are following the anchoring and glazing requirements as the
installation may be subjected to approval by a local building official. Failure to install
the systems correctly may result in additional labor expense as the building official may
require that you remove the system and reinstall it correctly. If you follow these simple
guidelines you will be able to make the transition smoothly from conventional glazing
systems to those that are designed to provide protection from Mother Nature.
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