Am I right? The IRC has no minimum rise height for stairways???

[Nick Gromicko]

We made it 4" in www.nachi.org/stairways.htm because a low rise height is a trip/fall hazard (people don't see it as a step).

[Jeffrey R. Pope]

You are correct. No minimum rise (R311.5.3.1). A 0" rise would be a ramp

[Nick Gromicko]

Short rises are a serious hazard on stairs, people don't recognize them as a step coming down. I've seen some treads intentionally carpeted with very different colors to alert people of a low rises.

[Nick Gromicko]

I should have looked at my morning emails first:

Dear Mr. Gromicko:

Re: Minimum riser height of the 2006 IRC

Unlike the 2006 IBC, which has a 4 inch minimum riser height (Section
1009.3, IBC/06), the 2006 IRC does not have any such requirement.

This opinion is based on the information which you have provided. We
have made no independent effort to verify the accuracy of this
information nor have we conducted a review beyond the scope of your
question. As this opinion is only advisory, the final decision is the
responsibility of the designated authority charged with the
administration and enforcement of this code.

Sincerely,

John S. Gonzalez
Technical Staff
INTERNATIONAL CODE COUNCIL
Chicago Dist. Office

[Michael Larson]

Originally Posted by gromicko

Short rises are a serious hazard on stairs, people don't recognize them as a step coming down. I've seen some treads intentionally carpeted with very different colors to alert people of a low rises.

I would say that depends on the tread depth. It's not really a problem as long as one can descend reasonably comfortably.

[rgrizzle]

I looked it up in the IRC Commentary and it states
"This code establishes that the maximum riser height is 7-3/4 inches. the IRC does not state a minimum riser height as does the IBC, where 4-inch limit is specified."

[Emmanuel J. Scanlan]

As Jeff stated the IRC code itself does not specify a minimum height.

2003 IRC:

311.5.3.1 Riser height.
The maximum riser height shall be 7 3/4 inches (196 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).

However the IRC does reference and use the following ANSI standard for minimum riser height. ANSI A117.1-1998

504.2 Treads and Risers.
All steps on a flight of stairs shall have uniform riser heights and uniform tread depth. Risers shall be 4 inches (100 mm) high minimum and 7 inches (180 mm) maximum. Treads shall be 11 inches (280 mm) deep minimum, measured from riser to riser.

So your minimum riser height is justified by at least one accepted, and major, standard.

[Nick Gromicko]

Good then, we're sticking with 4".

We're eventually going to come up with a stairway add-on to www.nachi.org/comsop.htm

[John Bowman]

I believe the UBC addresses it. This may help.

http://riserless-stairs.com/

[Nick Gromicko]

Thanks John. The author of that article is going to review our document.

[John Bowman]

Here is some more info for you out of the ADAAG.

<H4>Treads and Risers [4.9.2], Nosings [4.9.3]

Treads must be at least 11 inches wide and uniform. Uniformity is important not only between steps but along each step; curved stairs, where the width of each tread varies, do not meet this requirement. Variation in riser height along a set of stairs can be a tripping hazard. ADAAG requires the height to be uniform but does not specify a minimum or maximum height which is addressed by most local building codes. (The CABO/ANSI A117.1-1992 standard requires a riser height between 4 to 7 inches.)
People without full use of a leg may drag a foot when ascending stairs. A smooth transition from tread to tread is essential. Open risers and abrupt or extended nosings (i.e., projecting more than 1 ½ inches) can catch the toe. Angled or rounded nosings or sloped risers help prevent this hazard and provide a smoother transition. Straight risers without nosings are acceptable. ADAAG specifies the radius of the curvature of the leading edge of treads and the underside slope of angled or rounded nosings.

</H4>

[Bob Elliott]

Hmmm, I think back to all the natural stone or slate steps with extremly wide treads and have no recollection of tripping , unlike if it was unexpected at an indoor setting.
I think one should take the surroundings into account when reporting.

[Barry Adair]

many issues on this upscale over $1M condo

client busted his nose during the inspection coming out of the kitchen onto the angled landing

[klott]

Nick, I agree some of these stepdowns are dangerous, there needs to be a way to make them at least visible, especially in dark areas. Since I'm just offering opinions on my observations, I always mention them in my reports as possible trip hazards. If it kills the deal, then there never was much of one anyway. IMO

[Nick Gromicko]

Agreed.