A117.1 Chapter 4 & 5
This lesson finishes the accessible-route components the last lesson set aside: the sloped and vertical-circulation elements that carry a wheelchair user past a change in elevation. Sections 405 and 406, still in Chapter 4, cover ramps and curb ramps. Sections 504 and 505, in Chapter 5, cover stairs and handrails, which every GCHS project needs even though stairs themselves are never an accessible route; a stair has to meet these rules for the people who do use it, while the route around it does the accessibility work. The lesson closes with a short look at elevators and platform lifts, the vertical alternative to a ramp where elevation change is too great for a reasonable ramp run.
Section 405 defines a ramp as any part of an accessible route with a running slope steeper than 1:20. A ramp's running slope cannot exceed 1:12, though A117.1 allows a documented exception for existing buildings, permitting a steeper short ramp under its own separate table where a full 1:12 run genuinely will not fit. Cross slope on a ramp is capped at 1:48 maximum, the same limit that applies to ordinary walking surfaces. Section 405 also limits how much a single ramp run can rise before it needs a landing: 30 inches maximum rise per run.
Section 405 requires a landing at the top and bottom of every ramp run, at least 60 inches long in the direction of travel and at least as wide as the widest ramp run leading to it. Where a ramp changes direction between runs, the landing must be at least 60 by 60 inches. A landing gives a wheelchair user a level place to stop, rest, or change direction rather than being stuck on a continuous slope, and it is also where a second ramp run typically starts if the total rise of a site needs more than one run to reach grade. Section 405 also requires handrails on a ramp wherever its rise exceeds 6 inches; a short ramp with only a few inches of rise can be built without handrails, but anything higher needs them on both sides, with the handrail details covered later in this lesson. A ramp that stacks two or three runs together, each capped at 30 inches of rise with a landing in between, is a common way GCHS reaches a raised entry that a single run could not cover within the site's available length.
A curb ramp is the short, steep transition where an accessible route crosses a curb, typically at a parking lot or street crossing. Section 406 caps a curb ramp's running slope at 1:12 maximum, and requires a landing at least 48 inches by 48 inches, sloped no steeper than 1:48, at the top of a perpendicular curb ramp (at the bottom of a parallel one). The landing grows to 48 by 60 inches where it is constrained. This gives a wheelchair user room to turn and move onto the route beyond it rather than rolling directly off the ramp into traffic or a drop-off.
Stairs are never part of an accessible route themselves, but Section 504 still regulates them, since most buildings have stairs that non-wheelchair users, including people with low vision or limited stamina, need to use safely. Riser height is limited to a range of 4 to 7 inches, and tread depth must be at least 11 inches; a riser outside that range, or a tread shallower than 11 inches, creates an uneven, trip-prone rhythm that especially affects a person with limited mobility or vision. Open risers, where you can see through the stair from one flight to the next, are not permitted. Nosings, the leading edge of each tread, are limited to a rounded edge of 1/2 inch radius at most or a small bevel, and the leading 1 to 2 inches of every tread needs a solid strip of contrasting color across the full tread, or the durable warning markings the adopted building code requires, so the edge of every step is visible to someone with low vision.
Section 505 requires handrails on both sides of a stairway or ramp. The gripping surface has to sit 34 to 38 inches above the nosing line of a stair or above the ramp surface. The handrail needs at least 1.5 inches of clearance from the adjacent wall, so a hand can wrap fully around it, and a circular handrail's own diameter has to fall between 1.25 and 2 inches, again sized for a full hand grip. Handrails must extend at least 12 inches beyond the top and bottom of a ramp run and beyond the top of a stair; at the bottom of a stair, the extension instead has to run the length of one additional tread depth, so a person's hand has continued support as they step off the last riser.
Where an accessible route needs to rise more than a ramp can reasonably handle, A117.1 turns to elevators and platform lifts. Passenger elevators (Section 407) and limited-use/limited-application elevators (Section 408) must operate automatically, and Section 410 says platform lifts may not be attendant operated and must allow unassisted entry and exit. Private residence elevators get their own Section 409, which also requires automatic operation and sets a smaller car: at least 36 inches wide and 52 inches deep in new buildings, or 36 by 48 inches in existing buildings. A platform lift with a single door or doors on opposite ends needs a clear floor at least 36 by 52 inches in new buildings, or 36 by 48 inches in existing buildings. Type B dwelling units in Chapter 11 add their own exceptions to these sizes, covered in the later Type B lesson. For an elevator or lift serving a single home, GCHS staff should check Sections 409 and 410 rather than applying the full passenger elevator figures by default.
Ramp running slope: steeper than 1:20, not steeper than 1:12 (with a documented existing-building exception for steeper short ramps); cross slope 1:48 max; rise 30 in. max per run; landings at top and bottom of each run, 60 in. min length, as wide as the ramp, 60 by 60 in. where the ramp turns; handrails required where rise exceeds 6 in. (405). Curb ramps: 1:12 max running slope; landing 48 by 48 in. min at the top of a perpendicular curb ramp (406). Stairs: risers 4-7 in., treads 11 in. min, no open risers, nosing radius 1/2 in. max, contrast on the leading 1-2 in. of each tread (504). Handrails: 34-38 in. gripping height, 1.5 in. min wall clearance, circular diameter 1.25-2 in., extensions 12 in. min at ramps and top of stairs, one tread depth at the bottom of a stair (505). Elevators (407-409): automatic operation; platform lifts (410): not attendant operated; private residence elevator car 36 by 52 in. new, 36 by 48 in. existing (409).
Why this matters for GCHS
Ramps and stairs are two of the most visible, most inspected elements on any GCHS accessibility modification, and getting the slope, landing, and handrail numbers right at the estimating stage keeps a project from failing a walk-through after the work is already built. Because GCHS's role is construction management, inspection, and estimating rather than the hands-on ramp or stair carpentry itself, staff need to be able to check a proposed ramp run, landing size, and handrail height against these numbers before signing off on a contractor's plan, not after the concrete is poured.
1. Under Section 405, what running slope range defines a ramp?
2. Under Section 405, what is the maximum cross slope on a ramp?
3. Under Section 405, what is the maximum rise permitted for a single ramp run before a landing is required?
4. Under Section 405, what is the minimum length of a ramp landing?
5. A GCHS project is building a short entry ramp with a total rise of 5 inches. Under Section 405, are handrails required?
6. Under Section 406, what is the maximum running slope for a curb ramp?
7. A GCHS site plan shows a landing at the top of a perpendicular curb ramp measuring 40 inches by 40 inches. Under Section 406, does this satisfy the landing requirement?
8. Under Section 504, what riser height range is permitted on a stair?
9. Under Section 504, what is the minimum tread depth on a stair?
10. A GCHS inspector finds a rehab stairway with open risers and no contrast strip on the nosings. Under Section 504, is this compliant?
11. Under Section 505, what height range applies to a handrail's gripping surface above the ramp or stair surface?
12. Under Section 505, what is the minimum clearance required between a handrail and the adjacent wall?
13. Under Section 505, what diameter range applies to a circular handrail?
14. Under Sections 407 through 410, what operating requirement applies to elevators and platform lifts, and where does A117.1 address private residence elevators?