A117.1 Chapter 3
This is the first lesson in this course with real dimensions attached to it, and it is worth pausing on that. Chapter 3 of A117.1, titled Building Blocks, sets the basic space and reach numbers that every later chapter leans on: how much floor space a wheelchair needs, how high a switch can be mounted, how far something can stick into a hallway before it becomes a hazard. If GCHS staff already know the 2010 ADA Standards or UFAS from other work, that familiarity helps with the shape of these rules but not the numbers. A117.1's clear floor space and reach ranges are its own figures, and this lesson states only what is verified for A117.1 itself. Do not assume a number from a different standard carries over here; treat every dimension below as specific to A117.1-2017 and check the section cited whenever a project needs the primary source.
Section 302 requires ground and floor surfaces along an accessible path to be stable, firm, and slip-resistant. Carpet, where used, is capped at 1/2 inch of pile height. Any opening in a floor or ground surface, such as a grate or a gap between decking boards, must be small enough to block a 1/2-inch sphere from passing through, so a person's cane tip, crutch, or wheelchair caster cannot drop into it. These are baseline material requirements that apply everywhere an accessible route runs, not just at a single fixture.
Section 303 governs how abrupt a step or lip in a walking surface can be. A vertical change of 1/4 inch or less needs no edge treatment at all. A change greater than 1/4 inch, up to 1/2 inch, must be beveled at a slope no steeper than 1:2. Anything beyond 1/2 inch cannot be handled as a simple lip or bevel; it has to be built as a ramp instead. This section comes up constantly on GCHS rehab work, since an unramped threshold or a floor transition left slightly too tall is one of the most common, and most fixable, failures an inspector finds.
Section 304 requires a clear space somewhere in a room for a wheelchair user to reverse direction through a full turn. A117.1 allows two configurations. A circular turning space needs a 67-inch minimum diameter in new construction, or 60 inches minimum where the project is an existing building. Alternatively, a T-shaped turning space can be used. In new construction, the first of three options fits within an area 68 inches wide and 60 inches deep, with arms and base at least 36 inches wide; the other two options fit a 64-by-60-inch area but use wider arms and base. In an existing building, the T fits within a 60-inch square, with arms and base still 36 inches wide. Whichever shape is used, this is the space that lets someone enter a bathroom, bedroom, or kitchen and turn back around rather than being stuck facing one direction.
Section 305 sets the minimum stationary clear floor space a wheelchair needs in front of a fixture or control at 30 inches by 52 inches in new construction, and 30 inches by 48 inches where the project qualifies as existing construction. This new-versus-existing split is one of the clearest, most testable differences from other standards GCHS staff may know, where a single clear-floor-space number often applies regardless of new or existing work. On an A117.1 project, always confirm which figure applies before laying out a bathroom or kitchen clearance.
Section 306 covers the space that has to exist under a counter, lavatory, or similar fixture so a wheelchair's footrests and knees can slide underneath it. Toe clearance, the space at floor level, allows a maximum height of 9 inches, with a depth of 17 inches minimum up to 25 inches maximum, and a minimum width of 30 inches. Knee clearance, the space higher up for a person's knees, runs from 9 inches up to 27 inches above the floor, needs at least 11 inches of depth measured at the 9-inch height and at least 8 inches of depth measured at the 27-inch height, and also needs a minimum width of 30 inches. Together these numbers are what let a fixture project into a room while still leaving room for a wheelchair to roll partway underneath it.
Section 307 protects a person using a long cane or who has low vision from hazards mounted at chest or head height that a cane sweep along the ground will not detect. An object mounted between 27 and 80 inches above the floor can protrude no more than 4 inches into a circulation path (a wall-mounted handrail gets its own 4.5-inch allowance). Below 27 inches, an object can protrude further, since a cane sweep or a wheelchair's footrest will reach it first. Separately, any circulation path needs at least 80 inches of vertical clearance overhead, with a cane-detectable barrier required anywhere headroom drops below that minimum.
Section 308 sets how high or low a control can be mounted and still be usable from a seated position. Unobstructed forward reach runs from 15 inches minimum to 48 inches maximum. Unobstructed side reach uses the same 15-to-48-inch range, but only when the edge of the required clear floor space sits within 10 inches of the element being reached, approached from the side. Reaching over an obstruction changes the numbers. For an obstructed high forward reach, the clear floor space and knee and toe clearance must extend beneath the element at least as far as the reach depth. The maximum then stays at 48 inches where the reach depth is 20 inches or less, but drops to 44 inches where the reach depth is more than 20 and up to 25 inches. For an obstructed high side reach, the maximum is 48 inches at up to 10 inches of depth, and drops to 46 inches where the obstruction is up to 24 inches deep, as long as the obstruction itself is no more than 34 inches high and no more than 24 inches deep. As with clear floor space, do not assume a familiar reach-range number from another standard applies here; A117.1 sets its own figures for both forward and side reach.
Section 309 applies to anything a person operates by hand, light switches, thermostats, door hardware, faucet controls, and the like. An operable part has to sit within the reach ranges set by Section 308, and it has to be operable with one hand, without requiring a tight grasp, a pinch, or a twist of the wrist. The force needed to operate it is capped at 5 pounds. These are simple rules but they rule out a lot of common hardware, a round door knob or a stiff twist-style faucet handle neither belongs on an accessible modification.
Carpet pile: 1/2 in. max (302). Level changes: 1/4 in. unramped, 1/4-1/2 in. beveled at 1:2, over 1/2 in. needs a ramp (303). Turning space: 67 in. circle new / 60 in. existing, or a T-shape with 36 in. arms and base, within 68 by 60 in. new or a 60 in. square existing (304). Clear floor space: 30 by 52 in. new, 30 by 48 in. existing (305). Toe clearance: 9 in. max height, 17-25 in. depth, 30 in. min width; knee clearance: 9-27 in. height, 11 in. depth at 9 in., 8 in. depth at 27 in., 30 in. min width (306). Protruding objects: 4 in. max between 27 and 80 in. high; 80 in. min headroom (307). Unobstructed reach: 15-48 in. Obstructed high forward: 44 in. max at 20-25 in. depth. Obstructed high side: 46 in. max at up to 24 in. depth, obstruction 34 in. max high (308). Operable parts: one hand, no tight grasp, 5 lb max force (309).
Why this matters for GCHS
GCHS's estimators and inspectors are the ones who translate these numbers into a scope of work before a rehab crew ever picks up a tool, since GCHS handles construction management, inspections, and estimating rather than the hands-on plumbing or electrical labor itself. Getting clear floor space, reach range, and knee clearance right at the estimating stage, before a grab bar or lower counter goes in, avoids a costly rework order later. And because these are A117.1's own numbers, not the ADA's or UFAS's, a scope written from memory of a different standard can quietly fail an A117.1 inspection even when the work looks generous and accessible.
1. Under Section 302, what is the maximum carpet pile height on an accessible route?
2. Under Section 303, a change in level of 3/8 inch requires what treatment?
3. Under Section 304, what is the minimum diameter of a circular turning space in new construction?
4. Under Section 304, what is the minimum circular turning space diameter for an existing building?
5. Under Section 305, what is the minimum clear floor space in new construction?
6. A GCHS rehab project is being estimated as an existing-building scope under Section 305. What clear floor space figure applies in front of a fixture, and how does it compare to new construction?
7. Under Section 306, what is the maximum height of the toe clearance space?
8. Under Section 306, what height range does knee clearance cover above the floor?
9. Under Section 307, how far can an object mounted between 27 and 80 inches above the floor protrude into a circulation path?
10. Under Section 307, what is the minimum vertical clearance required through a circulation path?
11. Under Section 308, what is the unobstructed forward and side reach range?
12. A GCHS estimator is scoping a lowered switch above a counter that is 22 inches deep, with knee and toe space beneath it. Under Section 308's obstructed high forward reach rule, what maximum mounting height applies?
13. A GCHS project reaches sideways over an obstruction that is 20 inches deep and 30 inches high. Under Section 308's obstructed high side reach rule, does the 46-inch maximum apply?
14. Under Section 309, what force and grip requirements apply to operable parts?