Chapter 3 defines the fundamental building blocks of accessibility that are referenced throughout all other chapters. Floor surfaces, turning spaces, clear floor space, reach ranges, and operable parts — these are the measurements and requirements that form the basis of every accessible design. Understand these, and the rest of the Standards make much more sense.
Reading level📄 Plain language + legal text
CurrentlyStandard
All floor and ground surfaces along accessible routes must be stable, firm, and slip-resistant. This means no loose gravel, deep carpet, or slippery tile on paths people use to get around.
Example: A hotel can't have thick, plush carpet in the hallway leading to accessible rooms that would make wheelchair travel difficult.
Small bumps and steps in floor surfaces are a tripping and wheelchair hazard:
Up to ¼ inch: OK as-is (vertical)
¼ to ½ inch: Must be beveled (angled) at no steeper than 1:2
Over ½ inch: Must be treated as a ramp or curb ramp
A wheelchair user needs room to turn around. Two options are allowed:
Circular: A 60-inch diameter circle (5 feet across)
T-shaped: A T-shape where each arm is at least 36 inches wide
This space must be provided anywhere a wheelchair user might need to reverse direction — like at the end of a hallway, in a restroom, or in front of an elevator.
§304 Turning Space
Units:
Key numbers — Turning Space
60″Minimum diameter for a circular turning space (5 feet across)
36″Minimum width of each arm and stem in a T-shaped turning space
1:48Maximum floor slope in any direction within the turning space
Wherever someone in a wheelchair needs to use a control, reach something, or park beside an element, there must be a clear floor space of at least 30 inches by 48 inches (2.5 feet × 4 feet). This can be positioned for either a forward or a parallel (side) approach.
§305 Clear Floor Space
Units:
Key numbers — Clear Floor Space
30″ × 48″Minimum clear floor space at every accessible element (about 2.5 ft × 4 ft)
ForwardWheelchair faces the element — 48″ toward it, 30″ wide
ParallelWheelchair pulls up alongside — 48″ long, 30″ deep
When a wheelchair user needs to pull up under a counter, desk, or lavatory:
Toe clearance: At least 9 inches high and 17 inches deep under the element
Knee clearance: At least 27 inches high and 11 inches deep minimum, extending to 25 inches deep at 9 inches above the floor
Example: A reception desk must have a section low enough (34 inches max) with knee space underneath so a wheelchair user can pull up and interact face-to-face.
§306 Knee & Toe Clearance
Units:
Key numbers — Knee & Toe Clearance
27″Minimum height for knee clearance at the front edge
9″Minimum height for toe clearance (below 9″ is the toe zone)
25″Maximum total depth under the element (wall to front edge)
17″Minimum depth for toe clearance
30″Minimum width for both knee and toe clearance
Objects mounted on walls or posts cannot stick out into walkways where a person using a cane or who is blind might walk into them:
Objects between 27 and 80 inches above the floor can protrude no more than 4 inches from the wall
Objects below 27 inches can protrude any amount (a cane will detect them)
Freestanding objects on posts can protrude no more than 12 inches
Example: A wall-mounted fire extinguisher cabinet installed at 30 inches above the floor can only stick out 4 inches. A drinking fountain at 24 inches can protrude further because a cane can detect it.
Wall-Mounted Objects
Units:
Key numbers — Wall-Mounted Objects
27″The cane detection line — objects above this are invisible to a cane
≤ 4″Maximum protrusion for objects between 27″ and 80″ above the floor
No limitObjects at or below 27″ can protrude any amount (cane detects them)
Overhead Clearance
Key numbers — Overhead Clearance
80″Minimum overhead clearance in all walking areas (6 feet 8 inches)
BarrierWhere headroom drops below 80″, a cane-detectable barrier at 27″ or lower must warn people
Controls and operable parts must be within reach of a person in a wheelchair:
Forward reach (no obstruction): 15 inches minimum to 48 inches maximum above the floor
Side reach (no obstruction): 15 inches minimum to 48 inches maximum above the floor
If reaching over an obstruction (counter or shelf), maximum height decreases based on depth
Example: A thermostat mounted at 60 inches (5 feet) is too high. It needs to be at 48 inches (4 feet) or lower.
Forward Reach
Units:
Key numbers — Forward Reach
15″ – 48″Reachable zone when nothing is in the way (15 to 48 inches above the floor)
≤ 25″Maximum counter depth you can reach over — deeper than 25 inches means the control is too far
44″ – 48″Maximum height drops to 44 inches when reaching over a counter 20–25 inches deep
Side Reach
Key numbers — Side Reach
15″ – 48″Reachable zone when nothing is in the way — same range as forward reach
≤ 24″Maximum depth of any obstruction you have to reach over sideways
≤ 34″The obstruction can't be taller than 34 inches or it blocks the reach
46″ – 48″Maximum reach is 46 inches when the obstruction is 10–24 inches deep
Every control, handle, switch, or mechanism that people use must be operable with one hand and without tight grasping, pinching, or twisting of the wrist:
No more than 5 pounds of force to operate
Round doorknobs fail this test — lever handles are required
Light switches, faucet handles, thermostats, elevator buttons — all must comply
The Three Rules
Units:
Key numbers — Operable Parts
15″–48″Height range for all controls (same as reach ranges)
1 handMust work with one hand — no grasping, pinching, or twisting
≤ 5 lbsMaximum force to operate any control
Pass vs. Fail
Quick test — Does this control pass?
PassCan you use it with a closed fist? Lever, push, rocker, paddle — all pass.
FailDo you need to grab, twist, or pinch? Round knobs, twist handles — all fail.
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