Do Exit Stairs Require Nosings??

[liarchitect]

I have come across a new project in which the contractor has built the entire exit stair incorrectly in a commercial office building. The risers vary from 4 to 7.5 inches. I am trying to get a solution. But i can not find in the code if a nosing is required by code

I see the min tread side, max riser height, and the max nosing projections. I do not see anywhere that a nosing is required by code.

I alway have nosing because it makes a confortable stair, but are they required by code

Building

two stories (5000 sf per floor)

sprinklered

 

[RLGA]

A nosing is defined by the IBC as "the leading edge of treads of stairs and of landings at the top of a stairway flights." Thus, the transition from tread or landing to the riser at the front would constitute the nosing, whether projecting, angled back, or straight down; therefore, all stairs technically have nosings.

Section 1009.4.5 (2009 IBC) or Section 1009.7.5 (2012 IBC) provides requirements for the profile of a step.

 

[liarchitect]

thank you, so by definition we do not need a projection on a stair

 

[RLGA]

You're correct, there is no requirement to project the nosing.

 

[Jim B]

Maybe a bit off the forum topic since this is commerical, BUT the IRC does required nosing (IRC 2009,311.7.4.3) where as the IBC does not

 

[mtlogcabin]

Good catch but don't forget the exception

Exceptions:

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

 

[Glennman CBO]

In the IRC, the nosing is only required on 10" treads. If you have 11" treads, a nosing is not required. I believe that is why it is not required in the IBC, since all treads are 11", and nosings are really not needed with these larger treads. The nosing requirement with 10" treads gives the surface of the tread more area, even though it is still 10" tread nose to tread nose, the 10" tread area is actually from 10 3/4" up to 11 1/4" even though it is only 10" from nosing to nosing.

 

[stairNosing]

For your consideration, we have a stainless steel, custom flush-mount bull nose product that works with wood flooring.

http://www.stairnosing.com/

 

[mark handler]

2015 IBC

1011.5.5 Nosing and riser profile. Nosings shall have a curvature or bevel of not less than 1/16 inch but not more than 9/16 inch (14.3 mm) from the foremost projection of the tread. Risers shall be solid and vertical or sloped under the tread above from the underside of the nosing above at an angle not more than 30 degrees from the vertical.

1011.5.5.1 Nosing projection size. The leading edge (nosings) of treads shall project not more than 1 1/4 inches beyond the tread below.

1011.5.5.2 Nosing projection uniformity. Nosing projections of the leading edges shall be of uniform size, including the projections of the nosing’s leading edge of the floor at the top of a flight.

 

[mark handler]

2010 adasad