Everything in its Place
Report Addresses Curtainwall Fastener Selection
by Dean Lewis
The selection and use of proper fasteners is critically important
to the safe and satisfactory performance of curtainwall systems. A unique
combination of technical data and applications tutorial, the recently
updated Technical Information Report AAMA TIR A9-14, provides necessary
information to select and specify proper fasteners.
The information provided in this most recent AAMA update has never been
more critical. To ensure that their products meet the specifications for
which they are designed, it is essential that manufacturers of fasteners
maintain excellent quality control procedures in their plants, and that
their customers carefully determine that they are, in fact, getting fasteners
that meet their specifications.
“The problem of inferior fasteners
on the market has become serious over the past few years, with potentially
The problem of inferior fasteners on the market has become serious over
the past few years, with potentially disastrous results. Many fasteners
may be found to be substandard mechanically and dimensionally when checked,
even though they are marked as high-performance grades.
Protective coatings on fasteners may also be a problem. As a result of
more stringent environmental requirements and tightening economic pressures,
fewer manufacturers are applying adequate coatings to their products.
The quality and thickness of protective coatings in today’s market, particularly
on low priced fasteners, has become somewhat unreliable.
These concerns became so serious in the 1980s that the United States Congress
passed the Fastener Quality Act (FQA) in 1990 and amended the act in 1999.
This federal law was enacted to protect the public safety where citizens
were at risk due to faulty fasteners. However, the FQA covers only bolts,
nuts, screws, studs and load indicating washers of ¼-inch diameter or
greater or those requiring a grade mark. Products produced under a recognized
quality assurance program such as ISO 9000 are exempt from this act. Architects
and specifiers should consider adding this requirement to all fastener
In order to be certain that the fastener needed to meet design criteria
is provided, the designer must not only specify fastener size and type,
but also material, minimum mechanical properties, thickness and type of
protective coating required. The recently published TIR-A9 document offers
a fastener specification checklist for this purpose.
Given valid marketplace concerns, architects and specifiers must take
into account a variety of factors when selecting proper fasteners to ensure
the proper performance of curtainwall systems.
Updates and Additions
Here’s a quick top-five list of some of the updates and new
information in the document. AAMA TIR-A9:
1. Adds extensive information on hydrogen embrittlement;
2. Includes a safety factors section with a thorough explanation on how
the safety factors were derived for the range of fastener diameters. The
intent being to provide safety factors which are conservative, consistent
3. Updates information in Fastener Load Tables Commentary found in Section
4. Includes tables giving allowable tension, shear and bearing loads
for a range of different fastener sizes, for carbon steel and stainless
steel alloys; the pull-out strength of fasteners in aluminum substrates
is also addressed; and
5. Features updated and expanded information in Pull-out Strength sec-tion
to include equations for thick, thin and transition regions and thread
stripping of internal and external threads.
Dean Lewis is the educational and technical information manager
for the American Architectural Manufacturers Association in Schaumburg,
Architects' Guide to Glass & Metal
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