ADAAG Manual

Gratings [4.5.4]

Gratings can pose a hazard by catching or entrapping the tips of crutches and walkers or narrow wheels of a wheelchair. The spacing between grates and orientation to the direction of travel can reduce these risks. ADAAG requires a maximum opening dimension of ½ inch in one direction and that elongated openings be placed so that the long dimension is perpendicular to the dominant direction of travel. These requirements apply to gratings located in any walking surface, including courtyards and plazas, not just those on accessible routes.

Recommendation: ADAAG does not specifically address other types of openings or gaps in ground or floor surfaces, such as those between pavers or at expansion joints. Irregular paved surfaces where joint surfaces may be recessed below the level, of the paving unit can disrupt wheelchair maneuvering even if the differences in level are less than ¼ inch. The ½ inch horizontal maximum specified for gratings is a good rule of thumb for these openings as well. Gaps or openings wider than ½ inch should be avoided or else treated, especially where they run parallel to a direction of travel.