ADAAG Manual

General [4.5.1]

Many variables affect the performance of a given walking surface, including slope and cross slope, its material, jointing, texture, and finish, the presence of moisture or contaminants, the material that contacts it and the method of ambulation. Design guidelines cannot encompass all criteria contributing to the safety of a walking surface. ADAAG addresses surface material, texture, and finish and requires them to be "stable," "firm," and "slip-resistant." No standard or method of measurement exists for these characteristics except for slip-resistance.

A "stable" surface is one that is not permanently changed by ordinary contaminants or applied force so that when a contaminant or force is removed, the surface returns to its original condition under normal use. A "firm" surface is resistant to deformation by indentations or particles moving on or across it.

Slip-resistance is based on the frictional force necessary to keep a shoe heel or crutch tip from slipping on a walking surface under conditions likely to be found on the surface. The static coefficient of friction provides a close approximation of a surface's slip-resistance. ADAAG does not require compliance with a specified level of slip-resistance since the static coefficient of fiction, which can be measured in several ways, varies according to the measuring method used. (Recommended levels in the ADAAG appendix of 0.6 for level surfaces and 0.8 for ramps are advisory, not mandatory). Affected industries (floor finishes, ceramic tile, and plumbing fixtures) each employ a different testing method in designating the slip-resistance of their products. In the absence of any specified means of measuring slip-resistance, materials and products can be specified according to the values determined within the industry. ADAAG is not interpreted as prohibiting use of specific materials since texturing or other treatments may sufficiently enhance slip-resistance, though some alternatives, such as applied surfaces, will require greater maintenance (reapplication) than others. Recommendation: Slip-resistance should be specified according to the conditions likely to be found on the surface. Exterior routes and spaces that are not protected, lobbies and entrances, bathing facilities and other areas where floor surfaces are often wet, should have a higher level of slip-resistance.