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

or height.

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-

egories:

• 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

were qualified.

• 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

unit.

Sara Neiswanger

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.

www.glassguides.com

Architects’ Guide to Glass & Metal