NAFS User Guide 2014: A Lot of Work…and Worth the Effort

Paul Gary
August 20, 2014
COLUMN : Legal

AAMA, WDMA and the CSA recently released the user guide to AAMA/WDMA/CSA 101/I.S.2/A440 NAFS 2011. There, I just got through one of the longer acronym-laden titles ever known to the fenestration business. The NAFS 101 standards and guides represent the backbone of the window and door business in North America. The user guide must have taken a lot of effort to create, and you should become familiar with the work product. Kudos to those involved.

Over the years, what is now the NAFS 101 has provided the common basis for fenestration performance specifications in all relevant markets, and NAFS 101 provisions have been melded into the International Codes. NAFS 101 provisions also have become more numerous and complex. The array of titles and extended areas of NAFS 101 coverage has become as tough to track as the characters in a Dostoyevsky novel. At times, this has resulted in misinterpretation, disagreement and mistakes—all of which can increase costs as they can lead to unsatisfied consumers and bring on plaintiff lawyers.

AAMA describes the guide as “the latest product of the ongoing effort to harmonize fenestration standards in North America.” True, but it is more
than that. It provides an organized commentary on relevant issues either not explicitly addressed in the NAFS 101 or about which there has been lingering disagreement in the marketplace.

For instance, the guide clarifies that the air water structural tests within NAFS 101 are not designed to test product installation.

9.2.5 Test specimen installation. Evaluation of actual field installation details (anchorage, perimeter seals, etc.) and attachment to various rough opening materials is not part of [NAFS 101]…. The air, water, and structural tests required by [NAFS 101] are performed on test specimens installed in a fixture that permits installation in accordance with the manufacturer’s documented instructions. These tests are used primarily to evaluate the performance of the fenestration product and are not intended to test the performance of the installation, particularly the perimeter sealants between the fixture and the test specimen and the anchoring of the test assembly to the test fixture…

With respect to a lingering “debate” as to whether use of a design pressure reference necessarily includes any associated water resistance performance level, the guide reiterates that “DP does not include water.” Positive design pressure. Users of this standard/specification are advised that the positive design pressure is not an indication of water penetration resistance performance. To determine water penetration resistance performance, the user is referred to the Performance Grade (PG) portion of the primary designator and/or the water penetration resistance test pressure portion of the secondary designator...

Should an issue arise regarding downstream field mulling of product and the impact on the NAFS rating, see:

  • 4.6.4 Field mulling without manufacturers' involvement. NAFS Clause 4.6.4 establishes that field mulling without the manufacturers' involvement is not covered by NAFS.
  • 9.2.2 Composite units and combination assemblies. This standard/specification recognizes the option to rely upon individual testing of elements within a composite window, but states that the “user should be aware that other performance criteria (air leakage, water penetration resistance, etc.) can be affected at the interface of these products.” With this, manufacturers and resellers should consider communicating that reality downstream.


Section 11 contains a number of useful reminders from the basic mandatory testing of fenestration components, to testing by manufacturers of components to which the consumer will come in contact for the presence of lead. It also clarifies the elements of code-required window opening control devices and fall prevention devices.

I have highlighted just a few parts of the document. The User Guide is technical—not a good “summer read”—but is a must for your reference materials bookshelf. You need to become sufficiently familiar with it to recognize it as your road map into the meaning and required application of NAFS 101. If you are making windows and doors but not meeting the specific NAFS 101 requirements, and I suggest their logical extension, you may be held accountable for falling outside the industry standard.

Paul Gary is the principal of The Gary Law Group, a law firm based in Portland, Ore., emphasizing legal issues facing manufacturers of windows and doors. Write him at