Reviewing Window Test Reports
Project specifications almost always include requirements for submittal and approval of product test reports. For the design professional charged with submittal approval, the following checklist may be helpful, especially when assessing a window manufacturer's qualification to bid:
- Compare project configurations and details carefully against those tested. It is unreasonable to expect a perfect match, but basics such as glazing, weathering and maximum lock spacing should be consistent.
- Make sure test reports were issued by an American Architectural Manufacturers Association (AAMA)-accredited test laboratory, ensuring capability and independence.
- AAMA's "Architectural" AW Performance Class designation defines the most stringent requirements, and Wausau recommends it as the basis for operable window specifications. R, LC and CW Class windows are tested to much less stringent standards. Detailed requirements for all Classes are contained in the AAMA/WDMA/CSA 101/I.S.2/A440-11 North American Fenestration Standard (NAFS-2011) document, referenced in the International Building Code.
- Single-lite test units do not qualify commonly used combination units with fixed lites adjacent to vents, and should not be accepted as proof of compliance. Examples of combination units include fixed-over-fixed, double casements, fixed-over-projected or casement-next-to-fixed. Demand AW test results on meeting rails and stacking mullions.
- Required AW Class AAMA 910 cycle testing was made more stringent in the 2010 version, by increasing the number of operating cycles from 2,500 to 4,000, and adding thermal cycling. Demand AAMA 910-10 compliance, and be especially suspicious of any product that was tested to previous versions after the issuance of the 2010 version.
- "Downsize" testing of units smaller than the AW Class minimum gateway size is not allowed, unless the gateway size is first qualified at the minimum AW test pressure of 40 pounds per square foot.
- U-Factors determined in accordance with National Fenestration Ratings Council NFRC-100 are the basis of prescriptive compliance path requirements in Model Energy Codes. Do not accept results based on sizes other than NFRC standard sizes; this is an all-too-common, but potentially misleading practice. All U-Factors in Wausau's technical information are based on NFRC standard sizes.
- Unrepresentative edge-of-glass conditions, such as foam spacers, non-silicone insulating glass sealant and increased glass bite, can be used to make the reported thermal performance look better than it actually is. Make sure that the submitted U-Factors represent the specified edge components, not the residential-grade alternatives.
- Do not accept acoustical test results for "glass only," as rigid support provided by frames can have a significant, but unpredictable, effect on rated sound attenuation.
- Do not accept shock tube testing on standard size units as the sole proof of compliance with blast hazard mitigation requirements, unless all of the units on the project are within the size and configuration ranges established in the Department of Defense Unified Facilities Guide Specifications. Be aware that it is almost always necessary to prepare supplemental blast calculations.
While the checklist above advocates for stringency, some differences between the tested units and the units required for a given project are inevitable. Apply engineering judgment in the assessment of all conditions and testing criteria, including but not limited to:
- Because commercial windows are subject to almost unlimited anchorage and substrate variations, use structural calculations rather than test results to verify adequacy.
- Performance Grade as included in a standard product rating (e.g. AW-PG100) represents test pressure, not a given project's design wind load. Mullions and anchorage specific to the project should be designed for the latter.
- While most test laboratories now cite only a "records retention date," some laboratories still list an expiry date on their test reports. A test report is a snapshot in time, describing performance of a specific product on a specific test date, based on concurrent versions of the specific standards cited. A test report does not "expire" unless the product is changed or the standards are revised - however, certain residential certification/labeling programs require periodic retesting, most often at four- to 10-year intervals.
Wausau's registered professional engineers help navigate the technical and administrative details of codes and testing requirements for specific projects, ensuring compliance verification in a timely manner. All of Wausau's products support sustainable design goals and may contribute to meeting criteria for U.S. Green Building Council's LEEDŽ rating systems.
Salt Lake City Public Safety Building
Location: Salt Lake City, UT
Architect: GSBS Architects
Product(s) Used: 6250i and 7250i INvision Unitized Curtainwall
4250-Z Zero Sightline Operating Vents
ClearStory Sun Control system