G l a s s T e c h
Trying to Reason with Hurricane Season”
Substitutions That Meet Hurricane Codes
by Sara Neiswanger
housands of impact-resistant windows, doors
and skylights have been tested and certified since
Hurricane Andrew made landfall in 1992. As a
consequence of the billions of dollars in prop-
erty damage Andrew inflicted, more stringent
standards for window systems were adopted. The
General Rules for Substitution
General premises for substitution require that
three out of four initial specimens have passed all
the appropriate criteria in ASTM E1996 and that
the original specimens are identical in every way,
including anchorage and mounting. The general
premises that apply to any substitution are:
• Large size qualifies smaller as long as dimen-
sions do not exceed dimensions of tested width
requirements put into place called for testing of
window and door systems and changes to any
component, including framing materials, glazing,
sealants, weatherstripping, hardware and anchors.
In order to meet these testing requirements
while keeping down cost, manufacturers and
suppliers may consider various glazing and fram-
ing substitutions. Rules about what component
changes required retesting and what retesting was
required were developed by Miami-Dade Product
Control. (Miami Dade component substitution
rules are not contained in a single document and
are therefore not addressed here.)
ASTM International developed a formalized
system of component substitution similar to the
Miami-Dade rules. This is contained in the appen-
dix associated with ASTM E1996.
It covers general substitution principles and
detailed substitution allowances for glazing and
framing systems. There are three substitution cat-
• Small missile – all elements that are not infill
elements shall be allowed automatically.
• Automatically substituted elements shall be
allowed to be combined into a system without
requiring engineering analysis or testing.
• New components shall be equal to or stronger
than the components originally tested.
• Substitution shall not raise the design pressure
above that at which the three initial specimens
• Substitution is not allowed if a failure occurs
for any reason.
• No more than three substituted elements can
be combined before retest.
• Glazing tapes, sealants, adhesives and back bed-
ding substitution requires a single test.
• Glazed products must be impacted twice per
1. Automatic – requiring no additional testing;
. Engineering Analysis – requiring demonstrat-
ed or documented performance through a
review of materials that predicates a minimum
of equivalent performance; and
Glass Infil Panels Rules:
• Color change is automatic.
• Substitution of a glass coating is automatic once
it is determined that the product is durable and
compatible with all the components of the system.
• Individual glass ply thickness increase shall
require the testing of one additional specimen.
A substitution with a decrease in glass ply
thickness shall not be allowed.
• A glass type change from annealed to
heat-strengthened or chemically-strengthened
requires the testing of one additional specimen.
• Glass type change from heat-strengthened to
annealed or heat-strengthened to chemical-
ly-strengthened shall not be allowed.
. Single Specimen – requiring one specimen,
identical to the original specimen qualified with
the only difference being the element to be sub-
stituted (i.e. interlayer type for laminated glass).
Full qualification is defined as a minimum of
three new specimens being qualified with no credit
given for any past test specimens. Full qualification
is not considered part of the substitution parame-
ters as it is required when the desired substitutions
are too extensive for a single product and have
multiple variables that cannot be tested in a single
test. Full qualification is a new test program that
allows unlimited changes to any product as it is not • Glass type change “to” or “from” fully tem-
limited by previous design parameters. pered shall not be allowed.
Architects’ Guide to Glass & Metal