Guide to the ADA Standards

Is there a minimum distance between changes in level?

The standards do not require a minimum horizontal separation between changes in level of a ½” or less. Such level changes may need to be in close proximity, such as at raised thresholds (otherwise a minimum 48” separation will provide enough wheelchair space so that only one vertical change is negotiated at a time). Ramps and curb ramps, which must be used to span vertical changes greater than ½”, must have level landings and clearances at the tops and bottoms of each run to provide adequate separation and resting intervals between sloping surfaces.