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Bottom Riser Height Measurement Question?
- Thread starter tbz
- Start date
fatboy
Administrator
Measured at the actual rise.
tbz
Silver Member
So though we measure the steps nose to nose, that same match point is not used at the landing, and am I reading correctly you choose a point less than 11 but more than zero, so lets say 6"
PC & ICE, your points exactly are what I am focusing on with this question. You don't step directly down from the step at the bottom riser to the landing, your foot will land at some point off in front of the riser. Thus the riser height on a sloped landing are normally about 1/4" higher at the step point of the travel location at the same 11" distance out from the nosing at the bottom riser.
I pulled the 11" only because the code requires that point for the handrail extensions minimum.
But, what point makes sense, if you measure to the 11" point out, should not the landing surface be very uniform to the treads above for were the foot would land?
steveray
SAWHORSE
At 1:48"...it really shouldn't matter...No? Is this really a problem in the field Tom? I guess if you are absolutely maxed out and then pitched I could see it....But then I probably wouldn't measure it....
R311.7.7 Stairway walking surface. The walking surface of
treads and landings of stairways shall be sloped not steeper
than one unit vertical in 48 inches horizontal (2-percent
slope).
R311.7.7 Stairway walking surface. The walking surface of
treads and landings of stairways shall be sloped not steeper
than one unit vertical in 48 inches horizontal (2-percent
slope).
tbz
Silver Member
Steve,
The issue is more problematic than one would think, metal fabricators many times install the steel pan stairs based on the bench marks established by the contractor and the concrete company then follows later to fill and pour the areas.
In the last two years more and more fabricators are calling me about being called back because the stairs failed for the risers, mainly the bottom riser.
As you can figure 9 out of 10 times its the concrete work not the steel placement. But the fact that payments can be held in limbo for months till this is hashed out is very common.
So I am trying to figure out how to best instruct the fabricators on were and how to measure, everything is pretty cut and dry but currently the best tool we have has been establishing that the concrete pour is not correct from the upper level to the lower level.
As to the 1:48 slope on bottom landings the vast majority of the times on outside flights this is a common area where slope is not followed.
The issue is more problematic than one would think, metal fabricators many times install the steel pan stairs based on the bench marks established by the contractor and the concrete company then follows later to fill and pour the areas.
In the last two years more and more fabricators are calling me about being called back because the stairs failed for the risers, mainly the bottom riser.
As you can figure 9 out of 10 times its the concrete work not the steel placement. But the fact that payments can be held in limbo for months till this is hashed out is very common.
So I am trying to figure out how to best instruct the fabricators on were and how to measure, everything is pretty cut and dry but currently the best tool we have has been establishing that the concrete pour is not correct from the upper level to the lower level.
As to the 1:48 slope on bottom landings the vast majority of the times on outside flights this is a common area where slope is not followed.
Mr. Inspector
SAWHORSE
I have been inspection a lot of large warehouses lately with a lot of prefab metal stairways. Sometimes they get a lot of the bottom riser wrong a lot on one job while other jobs are perfect. I can't tell who's fault it is. One warehouse where the bottom risers were off also had some of the guards about an inch to low so I figured it was the stairway fabricators fault for the bad risers on this job..
Paul Sweet
Sawhorse
Sometimes somebody forgets to take finish flooring thickness into account and nobody catches it. This usually isn't a problem with resilient tile, but it can add up quickly with tile or stone flooring.
1Roger
Registered User
Yes the way you explained it is exactly the way I understand it to be, there is however an exception to allow the first riser to be less than 4" if the stairs adjoin to a sloped sidewalk I believe. And for your first question I have always measured to point A on your diagram however, logically that may be wrong but I'd rather not fail something unless it's specifically stated in the code.
tmurray
SAWHORSE
Here, code stipulates it is top of tread or landing to top of tread or landing.
Right, but you missed the point of the question. Suppose the sidewalk or ground slopes. If you measure right at the edge of the next step, you get 7" and all is well. But if you measure out at the end of the imaginary step ... 11" away ... you could get 9" rise. Look at the sketch in post 6.
tmurray
SAWHORSE
Landing area has to be flat. Otherwise it is a ramp. Code does not allow stairs to terminate to a ramp. You can do stairs to a leading to a ramp, but not stairs directly to a ramp... At least here in this crazy country.
What do you do for deck stairs that land on uneven ground? No tolerance for natural slope?
tmurray
SAWHORSE
A landing is not required for stairs serving a single dwelling unit, so we would just measure right in front of the nosing. For any other occupancy, a landing is required and would need to be flat.
ADAguy
Registered User
Consider a 24" deep sink counter in a RR with a 2% slope from the back wall to a floor drain. it is 34" max. T. O.S. at the wall but (+) 34" 2' out, is that a violation or an allowed tolerance?
tbz
Silver Member
Does not the code have the same restriction for slope on treads and landings, thus per your reason, why are treads measured nose to nose?
As to the landing being not sloped, in a perfect world, not only are they not sloped, but they are also inspected correctly.
Thus the circle around, why aren't the bottom risers measured 1 tread depth out?
Fail. The TOS is a maximum, not a defined dimension. The contractor should have installed at 33-3/4 to allow for typical construction conditions.
Mr. Inspector
SAWHORSE
Is my code book missing an exception for bottom landings for a single dwelling?
2015 IBC:
1011.6 Stairway landings. There shall be a floor or landing
at the top and bottom of each stairway. The width of landings
shall be not less than the width of stairways served. Every
landing shall have a minimum width measured perpendicular
to the direction of travel equal to the width of the stairway.
Where the stairway has a straight run the depth need not
exceed 48 inches (1219 mm). Doors opening onto a landing
shall not reduce the landing to less than one-half the required
width. When fully open, the door shall not project more than
7 inches (178 mm) into a landing. Where wheelchair spaces
are required on the stairway landing in accordance with Section
1009.6.3, the wheelchair space shall not be located in the
required width of the landing and doors shall not swing over
the wheelchair spaces.
Exception: Where stairways connect stepped aisles to
cross aisles or concourses, stairway landings are not
required at the transition between stairways and stepped
aisles constructed in accordance with Section 1029.
Code says you need a landing or a floor. So no landing is required if there is a floor?
tmurray
SAWHORSE
I use a different code book than you folks.
tmurray
SAWHORSE
I don't disagree with you that this creates consistency with how the remainder of the stairs are measured. However, as a building official I am not given any guidance on how to measure the rise height from a landing to the first tread, so I do it the easiest way possible for me. If someone wanted to push the issue and demonstrate that stairs that I found non-compliant met compliance when measured the way you advocate for, I would be amenable to this solution.
Sounds like a good suggestion for a code change.
ADAguy
Registered User
My point exactly, avoid max's and call for less than to allow for construction deviations.
my250r11
Sawhorse
You are correct if using the IBC for egress. the question on the deck stairs was for residential. The IRC only requires one egress door from a home and that is usually the front door.
A northern version I suspect!
Mr. Inspector
SAWHORSE
I don't think I said anything about a door and I thought we were on the IBC
But my IRC seems to be missing the this exception under 311.7.5.1"Risers" that risers for stairways that are not part of the required means of egress are exempt from this section and be any height you want.
my250r11
Sawhorse
Rick18071 said:
Is my code book missing an exception for bottom landings for a single dwelling?
2015 IBC:
1011.6 Stairway landings. There shall be a floor or landing
Is my code book missing an exception for bottom landings for a single dwelling?
2015 IBC:
1011.6 Stairway landings. There shall be a floor or landing
This was in response to your stair landing post. Chapter 10 is for egress in the IBC. Was only pointing out this is not in the IRC. A landing is not required for deck steps and such. I still measure for the consistency and here in NM you can have 8" rise and 9" tread in the adopted code. I would measure from the nose of the last step to the ground, landing, pavers ect.