Specifying accessible openings, part 1

by T.J. Gottwalt, CSI, CDT, AHC, Essex Industries

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limiting threshold height to one-quarter inch for wheelchair access or cart traffic is a wonderful idea

 

Over the past ten years, the Americans with Disabilities Act (ADA) has been an increasingly important force in the architectural openings industry. Building design has slowly evolved over the past decade to include many elements that were not previously common to architectural practice. Elements such as ramped entryways, automatic entrances, tactile signage, and elevator access have become commonplace in today's building designs. The architectural openings industry has adapted as well, with the virtual elimination of doorknobs, and the growing demand for products such as automatic operators, lever handles, ramped thresholds, and closers with reduced opening force. Let's examine some of the components of an opening, and what makes them important to accessibility and ADA compliance.

Starting at the floor, ADA states that changes in level up to 1/4 inch may be vertical without edge treatment. Changes in level between 1/4 inch and 1/2 inch must be beveled, with a slope no greater than 1:2.

 1/4 inch change in floor level at opening

Changes in level greater than 1/2 inch must be accomplished by means of a ramp not exceeding 1:12 slope.

sloped change in floor level at opening

ADA also requires that thresholds not exceed 3/4 inch for exterior sliding doors, or 1/2 inch for other doors. This means that typical saddle-type thresholds up to one half inch in height are acceptable. These are the standard in the industry, but limiting the threshold height to one-quarter inch for areas that may require wheelchair access or cart traffic is a wonderful idea. It makes it slightly more difficult to adjust a door sweep to make perfect contact with the sloped edge of the threshold, but the decrease in threshold height makes wheeling anything through the opening much easier.

 

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