Guide to Window Certifications, Standards, Ratings
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Window ertification from American Association for Window Manufacturers (AAMA)
:Window or door certification from the Window and Door Manufacturers Association (WDMA, formerly the National Wood Window and Door Association, NWWDA).
Window certifications & standards - what are the minimum window & door performance grades
Questions & answers about window performance, certifications, & grades

In this article series we discuss the certifications and standards for the performance of windows.

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Window Certification & Standards

In this article series we discuss the selection and installation of windows and doors, following best construction and design practices for building lighting and ventilation, with attention to the impact on building heating and cooling costs, indoor air quality, and comfort of occupants. This article includes excerpts or adaptations from Best Practices Guide to Residential Construction, by Steven Bliss, courtesy of Wiley & Sons.

Also see WINDOW EFFICIENCY Features & Ratings. See WINDOWS & DOORS our home page for window and door information, and also see WINDOW TYPES - Photo Guide for a photographic guide to window and door types and architectural styles.

It is always best to choose windows with third-party certification from American Association for Window Manufacturers (AAMA) or the Window and Door Manufacturers Association (WDMA, formerly the National Wood Window and Door Association, NWWDA).

Both the AAMA and WDMA are trade associations representing manufacturers of windows, doors, and skylights. The WDMA is limited to wood windows and doors, while the AAMA encompasses a wide range of materials, from wood, aluminum, vinyl, and fiberglass to the newest composites.

Voluntary Standards for Window Manufacturers

In 1997, the two groups joined forces to establish a unified standard for evaluating fenestration products, known as AAMA/NWWDA 101/I.S. 2-97 “Voluntary Specification for Aluminum, Vinyl and Wood Windows and Glass Doors.” It establishes four performance requirements for a completed window or door.

Structural ability to resist wind loads
Resistance to air leakage
Resistance to air infiltration
Resistance to forced entry

Products that are certified under 101/I.S. 2-97 are designated by a four-part code that denotes the type of window, the performance class, and performance grade. For example, the code C-R15 indicates a casement window (C) recommended for residential applications (R), with a performance grade of 15.

Performance Grade and Design Pressure for Windows

How well a window performs when subjected to heavy rains and high winds is indicated by its performance grade and design pressure. The design pressure is a structural rating only, while the performance grade also indicates that a window has met the water resistance and air infiltration standards for that grade (see Table 3-2 below).

The minimum recommended design pressure for residential doors and windows is 15 psf. A design pressure of 15 means a window has been tested to withstand sustained wind pressures of 22.5 psf, roughly equivalent to a 95-mph wind, applied to either side of the window, simulating both positive and negative wind pressures.

The test pressure is always 150% of the rated design pressure to provide a safety factor. To earn a performance grade of 15, a window must also pass a water pressure test of 2.86 psf, which simulates rainfall of 8 inches per hour with a wind speed of 34 mph. In coastal areas or other areas prone to heavy winds or hurricanes, higher grade windows are recommended and may be required by code.

Also see WINDOW TYPES - Photo Guide.

Industry Associations for Windows & Doors

American Architectural Manufacturers Association (AAMA) www.aamanet.org

Efficient Windows Collaborative www.efficientwindows.org

National Fenestration Rating Council (NFRC) www.nfrc.org Sustainable by Design www.susdesign.com

Shareware calculators for sun angles, solar heat gain, and shading

Window and Door Manufacturers Association (WDMA) www.wdma.com

-- Adapted and paraphrased, edited, and supplemented, with permission from Best Practices Guide to Residential Construction.

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Steven Bliss served as editorial director and co-publisher of The Journal of Light Construction for 16 years and previously as building technology editor for Progressive Builder and Solar Age magazines. He worked in the building trades as a carpenter and design/build contractor for more than ten years and holds a masters degree from the Harvard Graduate School of Education. Excerpts from his recent book, Best Practices Guide to Residential Construction, Wiley (November 18, 2005) ISBN-10: 0471648361, ISBN-13: 978-0471648369, appear throughout this website, with permission and courtesy of Wiley & Sons. Best Practices Guide is available from the publisher, J. Wiley & Sons, and also at Amazon.com.
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WINDOWS & DOORS - see detailed links at page left
BEST PRACTICES GUIDE: WINDOWS & DOORS

Basic Housing Inspection, US DHEW, S 352.75 U48, p.144, out of print, but is available in most state libraries; New York State version, ca 1955, source of our window parts and window repair sketches.
Best Practices Guide to Residential Construction, by Steven Bliss. John Wiley & Sons, 2006. ISBN-10: 0471648361, ISBN-13: 978-0471648369, Hardcover: 320 pages, available from Amazon.com and also Wiley.com. See our book review of this publication.
Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. (416) 964-9415 1-800-268-7070 info@carsondunlop.com. Thanks to Alan Carson and Bob Dunlop, for permission to use illustrations from their publication, The Illustrated Home which illustrates construction details and building components. Carson Dunlop provides home inspection education including the ASHI-adopted Home Inspection Training Program (home study course), publications such as the Home Reference Book, report writing materials including the Horizon report writer, and home inspect ion services. Alan Carson is a past president of ASHI, the American Society of Home Inspectors.

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Decks and Porches, the JLC Guide to, Best Practices for Outdoor Spaces, Steve Bliss (Editor), The Journal of Light Construction, Williston VT, 2010 ISBN 10: 1-928580-42-4, ISBN 13: 978-1-928580-42-3, available from Amazon.com
The Journal of Light Construction has generously given reprint permission to InspectAPedia.com for adaptations, quotations, or reproductions used at this website. All rights and contents of the JLC material are ©Journal of Light Construction and may not be reproduced in any form.
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Window Certification & Standards

Voluntary Standards for Window Manufacturers

Performance Grade and Design Pressure for Windows

Industry Associations for Windows & Doors

Questions & Answers regarding this article

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Technical Reviewers & References

Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair