A A M A A N A L Y S I S  
NAFS Levels the Playing Field  
Use it to Demonstrate Claims of Long-Term Performance  
B Y D E A N L E W I S  
erformance orientation has 2) Determining the likely maximum 2) Water penetration resistance.  
been the key that’s made AAMA/  
WDMA/CSA 101/I.S.2/A440,  
also known as the North American 3) Selection of the performance level  
Fenestration Standard (NAFS) for  
doors, windows and skylights, the  
vehicle for bringing newer framing  
wind speed experienced at the job  
site (consult local codes), and;  
Simulating wind-driven rain, water  
is sprayed at the product at a test  
pressure of 15 percent of the DP for  
all Performance Classes except AW,  
for which it is 20 percent of DP (both  
subject to defined minimums).  
required to withstand the force  
imposed by this wind speed.  
This latter parameter is the proj-  
materials to market on a level playing ect-specific Design Pressure (DP), 3) Air leakage resistance. NAFS speci-  
field. NAFS guides the rating of com- which is the force, expressed in  
pletely fabricated products as to how Pascals (Pa) or pounds per square  
well they perform under prescribed foot (psf), exerted by the peak wind  
conditions, a process that takes into velocity at that location. From this, the  
account the strengths and weaknesses Performance Grade and Performance  
fies the test pressure differential to be  
applied, as well as maximum infiltra-  
tion rates for different Performance  
in L/s • m2 or cfm/sf).  
of all framing materials.  
Class can be determined for fenestra-  
These three criteria, often abbrevi-  
Given the vast combinations of tion that will meet the defined envi- ated within the industry as “AWS” for  
window types, sizes and performance ronmental challenges.  
demands imposed by the design,  
Air,Water and Structural, are the foun-  
dation of fenestration performance  
and the primary elements for basic  
location and function of the building Performance Class  
in which they are to be used, speci-  
NAFS defines four Performance third-party certification. In addition  
fying windows for a given project can Classes (R, LC, CW and AW) with to the AWS ratings achieved, a given  
be a formidable task. NAFS provides a minimum Performance Class require- product must also comply with other  
meaningful yet flexible way to decode ments of 15 (corresponding to a DP of performance requirements, such as  
the various performance parameters at least 15 psf), 25, 30 and 40, respec- maximum operating force and resis-  
and arrive at an appropriate specifi- tively. These are not trivial criteria; by tance to forced entry.  
cation that matches them with unique simple calculation, they are equiva-  
project requirements without sorting lent to the force exerted by winds of The Short Form Shortcut  
through prescriptive material-related 76.5, 98.8, 108.3 and 125 mph, respec-  
Sorting through all these class-  
parameters. As fenestration products tively (note that your local code may es, grades and various requirements  
evolve and diversify in response to vary).  
expanding performance expectations,  
might seem daunting. However, one  
of the primary purposes of NAFS is to  
this guidance becomes more critical.  
Performance Grade  
simplify the job of the specifier and  
The specific performance level cover the essential details by condens-  
in the 2012 International Building of a fenestration product that falls ing all this information to the comple-  
Code and International Residential within a given Performance Class, tion of just two blanks in a short-form  
Code, covers 36 operator types (such designated by the above noted let- specification.  
as double hung, awning and newer ter codes, is defined by the numeric  
As rigorous as the basic NAFS  
configurations) employing all fram- Performance Grade (PG). The latter requirements are, long-term reliability  
ing materials including wood, metal for a given product is the DP (or great- depends on factors other than the ini-  
and various polymeric compounds er if desired) within each Performance tial performance of a finished product.  
such as vinyl, fiberglass and cellulosic Class, so long as it’s supported by all of We will cover how this is considered in  
composites. a continuation of this series, focused  
the following requirements:  
Using NAFS to select and specify 1) Structural performance. A window on components, in future issues.  
a fenestration product involves three  
basic steps:  
or door must withstand a wind pres-  
sure test load equivalent to one and Dean Lewis is technical manager,  
a half times the DP, applied to simu- training and education, for the American  
) Selecting the type of door, window  
or unit skylight desired;  
late the pressure effects of wind.  
Architectural Manufacturers Association.  
Door & Window Market