Colonial Style Window design, Clinton Hill Brooklyn (C) Daniel Friedman Guide to Window Certifications, Standards, Ratings

  • WINDOW CERTIFICATION & STANDARDS - CONTENTS: Window certification & standards guides
    • Window certifications 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
  • POST a QUESTION or READ FAQs about window performance, certifications, & grades

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

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Window Certification & Standards

Hurricane resistant windows required in parts of Floirida (C) Daniel FriedmanIn 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.

Photo at left: Florida requires hurricane and wind-resistant windows in some areas.

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).

(C) J Wiley, S Bliss

[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.

Industry Associations for Windows & Doors

American Architectural Manufacturers Association (AAMA)

Efficient Windows Collaborative

National Fenestration Rating Council (NFRC) Sustainable by Design

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

Window and Door Manufacturers Association (WDMA)

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

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.

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