Michael Ellars

michaelellars.com

Michael Ellars, AIA, APX, CSI, CDT, LEED AP, CASp

Chapter 11B, Division 5 (General Site and Building Elements)

2013 CBC Revisions:
Intervening Code Cycle


Chapter 11B, Division 5 (General Site and BUilding Elements) 

Stairway Treads and Risers

11B-504.2 Treads and risers. All steps on a flight of stairs shall have uniform riser heights and uniform tread depths. Risers shall be 4 inches (102 mm) high minimum and 7 inches (178 mm) high maximum. Treads shall be 11 inches (279 mm) deep minimum.

Exception: Curved stairways with winder treads are permitted at stairs which are not part of a required means of egress.

Added new exception for uniform riser heights and tread depths where a curved stair with winder treads is not part of the means of egress; such stairs are beyond the scope of the 2010 ADA Standards. As part of this change, DSA adopts the (existing) definitions for “means of egress” and “winder.”

Handrail Extensions in Existing Builidngs

11B-505.10 Handrail extensions. Handrail gripping surfaces shall extend beyond and in the same direction of stair flights and ramp runs in accordance with Section 11B-505.10.

Exceptions: … 3. In alterations, where the extension of the handrail in the direction of stair flight or ramp run would create a hazard, the extension of the handrail may be turned 90 degrees from the direction of stair flight or ramp run.

Clarified that Exception 3 applies to stairs as well as ramps consistent with 2010 CBC and logical intent.

Bottom Extension at Stairs

A lot of confusion on this one. Here is the old and new language side-by-side:

Original (2013)New (2015)
11B-505.10.3 Bottom extension at stairs. At the bottom of a stair flight, handrails shall extend at the slope of the stair flight for a horizontal distance equal to one tread depth beyond the last riser nosing. Such extension shall continue with a horizontal extension or shall be continuous to the handrail of an adjacent stair flight or shall return to a wall, guard, or the walking surface. At the bottom of a stair flight, a horizontal extension of a handrail shall be 12 inches (305 mm) long minimum and a height equal to that of the sloping portion of the handrail as measured above the stair nosings. Extension shall return to a wall, guard, or the landing surface, or shall be continuous to the handrail of an adjacent stair flight. 11B-505.10.3 Bottom extension at stairs. At the bottom of a stair flight, handrails shall extend at the slope of the stair flight for a horizontal distance equal to one tread depth beyond the last riser nosing. The horizontal extension of a handrail shall be 12 inches (305 mm) long minimum and a height equal to that of the sloping portion of the handrail as measured above the stair nosings. Extension shall return to a wall, guard, or the landing surface, or shall be continuous to the handrail of an adjacent stair flight.

This does not delete the requirement for the extension. Rather, it clarifies that the return is the last part of the extension; the deleted phrase implies that the extension is to return before the horizontal portion, then return a second time.