Guide to Window Certifications, Standards, Ratings

Window standards:

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.

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.

Industry Associations for Windows & Doors

Fenestration Performance Classes, Sources, Standards.

• American Architectural Manufacturers Association (AAMA) www.aamanet.org
  
  AAMA/WDMA/CSA 101/I.S.2/A440 (Second Edition) [PDF] (2008) [Excerpt Edition] North American fenestration Standard/Specification for windows, doors, and skylights.
  
  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 skylights & sliding glass doors: 0.3 cfm / sq.ft.
  
  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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