Section 12-B-J01. AJ501 - ALTERATIONS

APPENDIX JEXISTING BUILDINGS AND STRUCTURES

 

Appendix J, Existing Building and Structures, of the International Residential Code is adopted as Appendix J of the Residential Code with the following amendments.

 

AJ501ALTERATIONS

 

Insert new Sections AJ501.8.4 and AJ501.8.5 in Appendix J of the Residential Code to read as follows:

AJ501.8.4 Riser height.  The maximum riser height of stairs being altered or modified shall be 8 ¼ inches (210 mm).  The riser shall be measured vertically between leading edges of the adjacent treads.  The greatest riser height within any flight of stairs shall not exceed the smallest by more than 3/8 inch (9.5 mm).

 

AJ501.8.5 Tread depth.  The minimum tread depth of stairs being altered or modified shall be 9 inches (229 mm).  The tread depth shall be measured horizontally between the vertical planes of the foremost projection of adjacent treads and at a right angle to the tread’s leading edge.  The greatest tread depth within any flight of stairs shall not exceed the smallest by more than 3/8 inch (9.5 mm).  The radius of curvature at the leading edge of the tread shall be no greater than 9/16 inch (14.3 mm).  A nosing not less than 3/4 inch (19.1 mm) but not more than 1 1/4 inches (32 mm) shall be provided on stairways with solid risers.  The greatest nosing projection shall not exceed the smallest nosing projection by more than 3/8 inch (9.5mm) between two stories, including the nosing at the level of floors and landings.  Beveling of nosing shall not exceed 1/2 inch (12.7 mm). Risers shall be vertical or sloped from the underside of the leading edge of the tread above at an angle not more than 30 degrees from the vertical.

 

Exception:  A nosing is not required where the tread depth is a minimum of 11 inches (279 mm).

 

 

authority

Section 10 of the Construction Codes Approval and Amendments Act of 1986 (Act), effective March 21, 1987 (D.C. Law 6-216; D.C. Official Code § 6-1409 (2012 Repl.)) and Mayor’s Order 2009-22, dated February 25, 2009, as amended.

source

Final Rulemaking published at 61 DCR 3063 (March 28, 2014 – Part 2).

EditorNote

The District of Columbia Residential Code (2013), referred to as the “Residential Code,” consists of the 2012 edition of the International Residential Code for One- and Two-Family Dwellings, published by the International Code Council (ICC), as amended by the District of Columbia Residential Code Supplement (2013) (12 DCMR B). The International Residential Code is copyrighted by the ICC and therefore is not republished here. However, a copy of the text may be obtained at:http://publicecodes.cyberregs.com/icod/irc/2012/index.htm?bu=IC-P-2012-000002&bu2=IC-P-2012-000019.