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Bottom Riser Height Measurement Question?

tbz

tbz

Silver Member
Joined
Sep 10, 2010
Messages
1,255
Location
PA/NJ - Borderlands
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?
 
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.
 
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.
Click to expand...
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.
 
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.
 
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.
 
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.
 
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"
 
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.
Click to expand...
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.
 
Last edited:
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.
Click to expand...
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
StanleyTape.jpg
 
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.
Click to expand...
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.
 
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.
 
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.
Click to expand...
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.
 
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"?
 
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
 
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.
Click to expand...
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.
Click to expand...
tbz: I concur with this post.
 
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.
Click to expand...
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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