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What are the various window certification agencies and guidelines and associations: 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 (Steve Bliss, J Wiley & Sons) , by Steven Bliss, courtesy of Wiley & Sons.
Photo at left: Florida requires hurricane and wind-resistant windows in some areas.
[Click to enlarge any image]
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.
Window structural ability to resist wind loads - or wind pressure standards for windows
Window resistance to air leakage
Window resistance to air infiltration
Window 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: "Wind resistance".
How
well a window performs when subjected to heavy rains and
high winds is indicated by its performance grade and
design pressure.
The window design pressure (in psf) given below 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).
[Click to enlarge any image, photo or table]
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.
Window Design Pressure Ratings actually combine the window's resistance to water leaks, air leaks, and actual structural loading, where higher psf ratings mean a better window resistance to these three effects.
Window or Door PG or Performance Grade Ratings
A more-recent window performance rating scale are PG ratings.
Window PG-Ratings combine separate evaluations of a window's resistance to water infiltration, air infiltration, and structural loading failure by assigning points to the window's ability to resist each of those forces and then computing a total Window Performance Grade Rating number.
The result is a number that might describe a window that is very resistant to water and air leaks but has less resistance to structural failure - for example.
A hurricane-resistant entry door might score very high for wind resistance against structural failure: the door won't "blow in", but it's PG-Rating might be lowered if the door leaks air or water during hurricane conditions.
Watch out: window and door performance ratings described here do not mean that the window or door has that same level of resistance to airborne objects nor to sudden wind gusts that might occur during a tornado or hurricane.
Note that the latest edition of this standard was published in 2017. Copies of AAMA/WDMA/CSA 101/I.S.2/A440-17 can be purchased from the the associations listed immediately below.
American Architectural Manufacturers Association 1827 Walden Office Square, Suite 550 Schaumburg, IL 60143-4268 USA www.aamanet.org
Window & Door Manufacturers Association 1400 East Touhy Avenue, Suite 470 Des Plaines, IL 60018 USA www.wdma.com
Canadian Standards Association 5060 Spectrum Way, Suite 100 Mississauga, Ontario, L4W 5N6 Canada www.csa.ca
This edition supersedes the previous edition, published in 2005 under the title Standard/Specification for windows, doors, and unit skylights.
- Original source: http://aama-media.s3.amazonaws.com/9d5668a0-571e-11e6-8698-01db683ea9f5.pdf
American Society of Civil Engineers (ASCE) 7, Minimum Design Loads for Buildings (2010) available at https://www.asce.org/publications-and-news/asce-7
Excerpt: Minimum Design Loads and Associated Criteria for Buildings and Other Structures (ASCE/SEI 7-16)
An integral part of building codes in the United States, Minimum Design Loads and Associated Criteria for Buildings and Other Structures (ASCE/SEI 7-16) describes the means for determining dead, live, soil, flood, tsunami, snow, rain, atmospheric ice, earthquake, and wind loads, and their combinations for general structural design.
Structural engineers, architects, and building code officials will find the structural load requirements essential to their practice.
Efficient Windows Collaborative
www.efficientwindows.org
FGIA, Fenestration & Glazing Industry Alliance, 1900 E Golf Rd, Suite 1250
Schaumburg, IL 60173 USA, Email: CustomerService@FGIAonline.org Tel: (847) 303-5664
IRC, International Residential Code (2018) Section R301 provides design loads of all exterior cladding of residential structures—including fenestration or windows & doors
IRC R301, Tables R301.2(2) and R301.2(3) provide design wind loads for glazed openings according to the design wind speed of the location where construction is located, the average building height & the building's wind-exposure.
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 (Steve Bliss, J Wiley & Sons) .
More Detailed Window/Door Design Requirements & Standards
Windows & Doors are manufactured & selected to meet specific building, site, & local code requirements for the following engineering or architectural areas:
Window & Door Air Leakage Requirements - see AAMA/WDMA/CSA 101/I.S.2/A440 (NAFS)-17 or NFRC 400-17
Pass/fail criterion for swinging doors: 0.5 cfm / sq.ft.
Window & Door Wind Loads - discussed in more-detail above on this page
For window mullion design strenght see 2018 IRC (deflection is limited to L/175 of the length of the long edge of the glass)
also see AAMA 450-10, Voluntary Performance Rating Method for Mulled Fenestration Assemblies that may allow exceptions to the above.
Window & Door Dead Loads - see ASCE 7-10 & the 2018 IRC
Window & Door Impact Resistance - See the 2018 IRC Section R301.2.1.2 and see the wind speed maps provided in ASCE 7-16 or ASC 7-10.
Also see ASTM E1886-13a & ASTM E1996-2014a
Also see AAMA 506 testing specifications
Window Energy Performance: see the 2018 IECC and also see the 2018 IRC Chapter 11
Window Sill Heights: See the 2018 IRC and ASTM F2090;
For windows that are more than 6' above the exterior ground level, window sill heights must be at least 24" above the adjacent interior floor
or
The window opening size must be no more than 4"
Window opening force: for Window Opening Control Devices (WOCDs) - see ASTM F2090-17: no more than 15 pounds of force with two single or one dual action and window resets automatically once closed.
Window /Door Emergency Exit or Rescue Opening Size & Location - See the 2018 IRC Section R310 that requires an opening size achieved by "normal window opening" (without requiring special tools or methods) that is
Windows 24 inches high, 20 inches wide and 5.0 or 5.7 square feet in area
Skylights or "roof windows" whose opening bottom edge is within 44-inches of the floor's walking surface
Window Flashing Requirements: see the 2018 IRC R703.
Where mechanical flasigs are used, see AAMA 712-14
Where self-adhered membranes are used for flashing, see AAMA 715-15
Window Safety Glazing: See 2018 IRC R308.4 and also see ANSI Z97.1 (2014)
Site-built windows: see ASTM E330
Skylights / sloped glazing: see AAMA/WDMA/CSA 101/I.S.2/A440 (NAFS-17)
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In addition to any citations in the article above, a full list is available on request.
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.
Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.
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
In addition to citations & references found in this article, see the research citations given at the end of the related articles found at our suggested
Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. Tel: (416) 964-9415 1-800-268-7070 Email: info@carsondunlop.com. Alan Carson is a past president of ASHI, the American Society of Home Inspectors.
Carson Dunlop Associates provides extensive home inspection education and report writing material. In gratitude we provide links to tsome Carson Dunlop Associates products and services.