NAFS Exhibits Cross-Border Diversity

The North American Fenestration Standard (NAFS) was jointly developed by AAMA, the Canadian Standards Association (CSA) and WDMA. Specifically, Canadian input is represented by members of the CSA Technical Committee on the Performance Standard for Windows, under the jurisdiction of the Strategic Steering Committee on Building Products and Systems, and by the US/Canada Joint Document Management Group (JDMG).  NAFS is referenced in the National Building Code of Canada, as well as the U.S.-based International Building Code and International Residential Code.

While most of the performance requirements in NAFS apply equally in the U.S. and Canada, there are some differences between the two countries’ requirements. Of particular note are those dealing with operating force, maximum water penetration resistance test pressure and air leakage measurement.

Window and Sliding Door Requirements Specific to Canada

The U.S. caps water penetration resistance test pressures at 580 Pa (12.11 psf), while Canada extends this to 720 Pa (15.04 psf).

Maximum operating forces for sliding doors of all four classes in Canada are the same as for the U.S. requirements in the R and LC classes only: 135 Newtons to initiate motion (30.35 lbf) and 90 N (20.23 lbf) to maintain motion. In the U.S., forces for both CW and AW classes are higher at 180 N (40.47 lbf) to initiate motion and 115 N (25.85 lbf) to maintain motion.

Canadian provisions of NAFS-11 call for tighter air infiltration criteria than for the U.S., especially for fixed windows and doors, and require air leakage exfiltration testing in addition to the standard air infiltration. Two options (A2 and A3 levels) are provided for measuring infiltration/exfiltration for all product operator types. An additional level is provided for fixed windows and fixed doors. At a minimum, operating windows and doors must meet the A2 level air leakage requirements (1.5 liters per second per square meter [L/s • Ÿ m2], or 0.30 cfm/ft2 when tested at a 75 Pa (1.57 psf) pressure difference. A product that successfully achieves the Canadian air infiltration/exfiltration A3 level must exhibit no more than 0.5 L/s • Ÿ m2, [0.10 cfm/ft2] when tested at the same differential pressure. Fixed windows and fixed doors must meet a separately specified air leakage requirement, which is 0.2 L/s • m2 [0.04 cfm/ft2] at the same pressure difference. In the U.S., both operable and fixed R and LC class products must meet the single requirement of 1.5 5 L/s • m2 (0.30 cfm/ft2).

Separate A2, A3 and fixed requirements also apply to Canadian CW and AW class products, as well as separate test pressure differences to measure infiltration and exfiltration. The U.S. does not make that distinction.

Side-Hinged Doors (All Classes)

Because a side-hinged door (SHD) system can be expected to operate a significantly greater number of times and to a greater severity during its design life than a typical sliding door, cycling performance is evaluated.

The basic U.S. and Canadian performance requirements for SHDs are the same at both gateway and optional performance grades, with the previously noted exceptions applicable.

For SHD air infiltration the U.S. makes no distinction between operable and fixed products, while Canada does – as well as applying the successively more stringent A2, A3 and fixed performance levels. At a minimum, operating doors must meet the A2 level air leakage requirements, and fixed doors must meet the fixed level air leakage requirements for both infiltration and exfiltration.Water Penetration Resistance Test

It is not always feasible for side-hinged door systems to meet the substantial water penetration resistance requirements of other fenestration products. For this reason, the “Limited Water” (LW) designation was developed. It should be noted, however, that a LW door system is NOT a door system that can only meet a water rating when tested at 0 Pa (0.0 psf); An LW door system is any where the water penetration performance is less than the equivalent Performance Grade of the system. This does not necessarily mean the door system performs poorly in water penetration testing. As an example, a door system with a structural design pressure of DP65 (65.16 psf) and a water penetration performance of 440 Pa (9.20 psf) (the equivalent water performance of a PG60 door system) would be rated as an LW door system.

There is a misinterpretation in Canada that LW door systems can only be used in weather-protected areas, but this is not the case.

With the specimen closed and locked, all specimens (except those rated for limited water at 0 Pa [0.0 psf]) are subjected to a complete four-cycle water penetration resistance test in accordance with ASTM E547. AW-class specimens are tested in accordance with both ASTM E547 and ASTM E331. Again, for U.S. applications, the water penetration resistance test pressure is capped at 580 Pa (~12.11 psf); 720 Pa (~15.04 psf) in Canada.

When testing for a limited water rating at 0 Pa (0.0 psf), testing is per ASTM E331; if for an LW greater than 0, ASTM E547 applies.

The pressures required for water and structural performance are not necessarily the same for US and Canadian markets. Performance grades (PG) for doors are defined in NAFS, and water and structural test pressures for each performance grade are based upon the PG value. For example, a PG40 system must pass water testing at a pressure of 0.15 x 40 = 6.0 psf, and structural testing at 1.5 x 40 = 60 psf. The US market follows this method for determining the required test pressure levels. CSA A440S1 does not use this method to determine the water and structural test pressures required. Instead, the pressures required to meet Code in Canada are determined either by calculating specific equations, or by utilizing provided tables which are based upon climate design data published by Environment Canada. They provide prescriptive values for both water and wind conditions for each province and for cities and towns within each province, and vary according to building height. As a result, the required water and structural test pressures for a given location are not necessarily multiples of the PG number. For example, in Calgary, Alberta for open terrain locations the water test level requirement is 330 Pa (PG45), while the required pressure for structural testing is 2160 Pa (PG30).

Hardware Standards

NAFS also references several door hardware-related standards, applicable both in the U.S. and Canada. These are:

AAMA 906, Voluntary Specification for Sliding Glass Door Roller Assemblies

AAMA 907, Voluntary Specification for Corrosion Resistant Coatings on Carbon Steel Components

AAMA 910, Voluntary “Life Cycle” Specifications and Test Methods for AW Class Architectural Windows and Doors

AAMA 920, Specification for Operating Cycle Performance of Side-Hinged Exterior Door Systems

AAMA 925, Specification for Determining the Vertical Loading Resistance of Side-Hinged Door Leaves

AAMA 930, Voluntary Specification for the Water Penetration Resistance and Structural Load Performance of Locking/Latching Hardware Used in Side-Hinged Door Systems

This last specification applies only to locking/latching hardware that is not validated for use through testing in the same or equivalent series/model/design side-hinged door system in which it is to be provided to the marketplace.

In addition to the U.S.-Canadian differences written into NAFS itself, CSA publishes a Canadian Supplement to NAFS: CSA A440S1-09, Canadian Supplement to AAMA/WDMA/CSA 101/I.S.2/A440, NAFS — North American Standard/Specification for Windows, Doors, and Skylights. It provides additional requirements for compliance in Canada as prepared by the CSA Technical Committee on the Performance Standard for Windows [and Doors].

Note that while the U.S. is on a three-year building code cycle, Canada is on a five-year cycle. Canada’s current National Building Code, applicable in most local jurisdictions, is dated 2010; hence, it recognizes NAFS-08 (for which the 2009 Canadian Supplement applies). There is technically no Canadian Supplement to NAFS-11, because the latter is not yet formally recognized – although the supplement most likely provides reliable guidance for the Canadian application of NAFS-11.