# Bottom Riser Height Measurement Question?



## tbz (Jun 11, 2021)

Ok,

This might seem like an odd question but I have always looked at the bottom landing measuring point to be the same as the nose to nose measuring point of the treads.

Example:

Risers are measured from the tip of the nosing line of a tread to the next same point on the tread below.
For the Top landing the starting nosing point to the nosing point of the tread below
*But when you get to the bottom landing, do you measure at the riser or to the landing at a point equal to the last tread depth, like the handrail extension is required to be?*


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## fatboy (Jun 11, 2021)

A little confused on the question. Image?


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## Pcinspector1 (Jun 11, 2021)

It's a rise, shouldn't it be in the 3/8-inch adjustment area at the required landing? 

I see that last step off a bit too in the field.


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## ICE (Jun 11, 2021)

Pcinspector1 said:


> It's a rise, shouldn't it be in the 3/8-inch adjustment area at the required landing?
> 
> I see that last step off a bit too in the field.


It doesn't get worse than that.  People of a certain age will establish a gate as they descend stairs.  They might look at the first couple of steps and then their brain takes over with the realization the the rest of the steps are the same as the first few.  When they hit the last step that is radically different it throws them off balance and they hurt themselves.  The bottom step is the worst place to have this happen.


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## Msradell (Jun 11, 2021)

I usually just put a straight edge on the steps and major for the bottom of it to the top of the next step. That is it seems to be the same within the allowable tolerance (3/8") compared to all the others. There is no exception for the bottom in the code.


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## tbz (Jun 12, 2021)

OK, thought this was simpler, here is a sketch


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## Msradell (Jun 12, 2021)

I normally have seen the height measured at the nose of each step to the top of the steps below it. That certainly the easiest place to measure.


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## steveray (Jun 14, 2021)

Measure at the nose, not that it should be all that different, but only 3/8 makes it tough with a pitched landing I guess....


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## Inspector Gift (Jun 14, 2021)

tbz said:


> OK, thought this was simpler, here is a sketch
> 
> View attachment 7966


We measure the bottom riser vertical distance to the landing.  Keep it simple.


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## e hilton (Jun 14, 2021)

25/32" ... you're kidding, right?   I know you didnt measure that with a normal construction tape measure.


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## tbz (Jun 14, 2021)

1st off let me focus on the purpose of the post, I am looking to get an idea as to were many of you measure the bottom landing to tread above for riser height,  only.

Reason for my question is, no one steps down at the point directly below the nosing above, hence the reason treads and risers are measured nosing to nosing on the flight.  

as to the other question of the 3/8" tolerance, that has nothing to do with the question, only the point you measure to is in question.

Now on to the fine use of the tape measure, the sketch shown is just that a sketch of a common layout seen in my area, not an actual specific set of stairs.  The measuring to a 32nd is able to be done with any standard tape measure, the lines exist even on a $5.00 Stanley 16ft LeverLock from Homedepot.  Since most of my work is done with metal fabricators the precision setting in my CAD software is set very tight, nothing more or less.


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## Paul Sweet (Jun 14, 2021)

7/32" is within the tolerance of IBC 1011.5.4.  I'm guessing the bottom landing slopes 1/4" per foot (2%) while the treads are level.

I think the reason for measuring at the nosing line is to prevent people from cheating an extra 1/4" per step by making the steps 7" straight down from the nosing then sloping the tread down another 1/4"


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## ICE (Jun 14, 2021)

tbz said:


> The measuring to a 32nd is able to be done with any standard tape measure, the lines exist even on a $5.00 Stanley 16ft LeverLock from Homedepot.


I can tell that it's been a long time since you have purchased a Stanley tape-measure.  I'm guessing that you filled up with 50 cent a gallon gasoline on the way to the store.


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## Sifu (Jun 14, 2021)

I measure at the leading edge of the tread.


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## tbz (Jun 14, 2021)

ICE said:


> I can tell that it's been a long time since you have purchased a Stanley tape-measure.  I'm guessing that you filled up with a 50 cent a gallon gasoline on the way to the store.


Was Paying $2.879 last month when I picked this one up at HomeDepot and the last time I checked the little line between 1/16" marks is a 32nd, though I am sure not as precise as my calipers


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## Beniah Naylor (Jun 14, 2021)

The Stanley FatMax doesn't do 1/32s, but the 16' Stanley I bought for doing cabinetry a few years ago had 1/32s on the first 12 inches.


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## e hilton (Jun 14, 2021)

tbz said:


> Since most of my work is done with metal fabricators the precision setting in my CAD software is set very tight, nothing more or less.


Thats a fair answer.  
Im just a little peeved because inam dping punch list work after an outside architect audited a project.  Some items he has flagged as wrong because the millwork counter is 1/16" too high.  And he flagged a restroom lav as being 2" too close to the wall, and it turns out he mismeasured, the lav is exactly correct.


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## Msradell (Jun 14, 2021)

Since this discussion evolved into measurement I'll throw one in. I was reviewing some concrete footing drawings a couple weeks ago and the engineer who designed them had some of the measurements down to 1/128"! When contractors are setting forms for footings you are lucky if they come within 1/2.


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## tbz (Jun 15, 2021)

e hilton said:


> Thats a fair answer.
> Im just a little peeved because inam dping punch list work after an outside architect audited a project.  Some items he has flagged as wrong because the millwork counter is 1/16" too high.  And he flagged a restroom lav as being 2" too close to the wall, and it turns out he mismeasured, the lav is exactly correct.


The fine art to using a tape measure correctly, or at minimum being able to read it correctly.

Talking about tape measures is not really that off post since the question is about where and how to measure the riser height at different parts of the stair flight. 

as to the precision level to read a tape it all depends on the need, use and most important craftsmen using the device.  

I have seen many a concrete steps installed that were more precise than 1/16" of an inch, these were old school masons using the water level method for setting forms, which was replaced by the laser level, but being able to read the device and use the device correctly, comes down to the person behind the device caring about the product they are producing.  Today I find that there are very few left who care about what they are doing which translates into the results you see IMO.

As to my OP, the question came about for 2 reasons, the first to see how many actually measure the bottom riser the same way the rest of the risers in the flight are to be measured.  The second was to use this in a training we are doing for fabricators and designers, to show them what inspectors are looking at when inspecting the tread and risers on a flight.


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## tbz (Jun 15, 2021)

So lets circle back to the note about the 3/8" tolerance.

The way I read this section is as follows.

You measure all your tread depths and riser heights
the shortest riser can't be more than 3/8" less than the tallest riser within the flight
the shortest tread can't be more than 3/8" less than the longest tread within the flight
Period


The 3/8" tolerance does not allow for the tallest riser within the flight to exceed the 7" nor reduce the shortest to be less than 4"
It is a tolerance that is boxed in between the 2 numbers, being the minimum and maximum.

 How do you see the 3/8"?


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## steveray (Jun 15, 2021)

Exactly as you wrote it...


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## mtlogcabin (Jun 15, 2021)

You would measure where the foot will land which will be just in front of the nosing not 11 inches away from the nosing. Only a kid jumping from the upper risers will land that far in front of the nosing of the riser


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## Pcinspector1 (Jun 15, 2021)

tbz said:


> as to the other question of the 3/8" tolerance, that has nothing to do with the question, only the point you measure to is in question.


It has everything to do with measuring stairs for code. Sorry I didn't pick up the jest of the question. As ICE posted the last step can be an issue when going down a flight of stairs. I was trying to state that the last step is the one is see off the most when doing rough-in and final inspections.


tbz said:


> The 3/8" tolerance does not allow for the tallest riser within the flight to exceed the 7" nor reduce the shortest to be less than 4"
> 
> It is a tolerance that is boxed in between the 2 numbers, being the minimum and maximum.


tbz: I concur with this post.


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## ADAguy (Jun 15, 2021)

ICE said:


> It doesn't get worse than that.  People of a certain age will establish a gate as they descend stairs.  They might look at the first couple of steps and then their brain takes over with the realization the the rest of the steps are the same as the first few.  When they hit the last step that is radically different it throws them off balance and they hurt themselves.  The bottom step is the worst place to have this happen.


One of your best responses to date ICE. Thank you
Now please explain why residential stairs only have one handrail in many cases?


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## Inspector Gift (Jun 15, 2021)

ADAguy said:


> One of your best responses to date ICE. Thank you
> Now please explain why residential stairs only have one handrail in many cases?


because I;m holding my cane in the other hand!


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## fatboy (Jun 15, 2021)

Measured at the actual rise.


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## tbz (Jun 16, 2021)

mtlogcabin said:


> You would measure where the foot will land which will be just in front of the nosing not 11 inches away from the nosing. Only a kid jumping from the upper risers will land that far in front of the nosing of the riser


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?


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## steveray (Jun 16, 2021)

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).


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## tbz (Jun 16, 2021)

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.


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## Rick18071 (Jun 17, 2021)

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..


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## Paul Sweet (Jun 17, 2021)

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.


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## 1Roger (Jun 21, 2021)

tbz said:


> So lets circle back to the note about the 3/8" tolerance.
> 
> The way I read this section is as follows.
> 
> ...


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.


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## tmurray (Jun 21, 2021)

Here, code stipulates it is top of tread or landing to top of tread or landing.


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## e hilton (Jun 21, 2021)

tmurray said:


> 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.


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## tmurray (Jun 21, 2021)

e hilton said:


> 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.


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.


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## e hilton (Jun 21, 2021)

tmurray said:


> 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?


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## tmurray (Jun 21, 2021)

e hilton said:


> What do you do for deck stairs that land on uneven ground?   No tolerance for natural slope?


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.


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## ADAguy (Jun 21, 2021)

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?


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## tbz (Jun 21, 2021)

tmurray said:


> 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.


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?


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## e hilton (Jun 21, 2021)

ADAguy said:


> 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?


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.


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## Rick18071 (Jun 22, 2021)

tmurray said:


> 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.


*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?*


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## tmurray (Jun 22, 2021)

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
> ...


I use a different code book than you folks.


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## tmurray (Jun 22, 2021)

tbz said:


> 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?


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.


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## ADAguy (Jun 22, 2021)

My point exactly, avoid max's and call for less than to allow for construction deviations.


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## my250r11 (Jun 23, 2021)

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
> ...



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.


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## Pcinspector1 (Jun 23, 2021)

tmurray said:


> I use a different code book than you folks.


A northern version I suspect!


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## Rick18071 (Jun 24, 2021)

my250r11 said:


> 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.


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.


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## my250r11 (Jun 25, 2021)

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


my250r11 said:


> 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.
> I don't think I said anything about a door and I thought we were on the


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.


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