# Death by Stairwell



## jar546 (Jun 28, 2020)

I enjoyed this history lesson:


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## cda (Jun 28, 2020)

Very interesting

And someone built a stair rise run, testing machine!


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## ICE (Jun 28, 2020)

The video on electricity was shocking.


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## Glenn (Jun 28, 2020)

I've been sharing the new york subway video for quite some time.  This one was also interesting.  Thanks.


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## e hilton (Jun 28, 2020)

Very interesting about the subway stairs.  Wish they had said what the difference is with the odd step.


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## e hilton (Jun 29, 2020)

Ok, i did a little research on the subway steps.  Turns out the difference was 1/2” and it was corrected in 2012 right after the video was published.  No idea how long it had been that way.


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## e hilton (Jun 30, 2020)

Question for the experts ...

what is the allowable variation in riser height?   I had thought it was no more than 1/4” between adjacent treads, and no more the 3/8” total for the run.


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## classicT (Jun 30, 2020)

e hilton said:


> Question for the experts ...
> 
> what is the allowable variation in riser height?   I had thought it was no more than 1/4” between adjacent treads, and no more the 3/8” total for the run.


*R311.7.5.1 Risers*
The riser height shall be not more than 73/4 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). Risers shall be vertical or sloped from the underside of the nosing of the tread above at an angle not more than 30 degrees (0.51 rad) from the vertical. Open risers are permitted provided that the openings located more than 30 inches (762 mm), as measured vertically, to the floor or grade below do not permit the passage of a 4-inch-diameter (102 mm) sphere.

*Exceptions:*

The opening between adjacent treads is not limited on spiral stairways.
The riser height of spiral stairways shall be in accordance with Section R311.7.10.1.

*R311.7.5.2 Treads*
The tread depth shall be not less than 10 inches (254 mm). The tread depth shall be measured horizontally between the vertical planes of the foremost projection of adjacent treads and at a right angle to the tread's leading edge. The greatest tread depth within any flight of stairs shall not exceed the smallest by more than 3/8 inch (9.5 mm).

*R311.7.5.2.1 Winder Treads*
Winder treads shall have a tread depth of not less than 10 inches (254 mm) measured between the vertical planes of the foremost projection of adjacent treads at the intersections with the walkline. Winder treads shall have a tread depth of not less than 6 inches (152 mm) at any point within the clear width of the stair. Within any flight of stairs, the largest winder tread depth at the walkline shall not exceed the smallest winder tread by more than 3/8 inch (9.5 mm). Consistently shaped winders at the walkline shall be allowed within the same flight of stairs as rectangular treads and do not have to be within 3/8 inch (9.5 mm) of the rectangular tread depth.​
*Exception:* The tread depth at spiral stairways shall be in accordance with Section R311.7.10.1.​


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## Glenn (Jun 30, 2020)

Has anyone else noticed how the IRC only requires uniformity of riser height and tread depth in each single flight of stairs (can change after a landing).  However, the section for nosing projection uniformity(R311.7.5.3) states the requirement is for "stairways" (includes all flights on both sides of an intermediate landing).

I have already prepared a modification proposal for the 2024 IRC to change the nosing uniformity to "flight of stairs".  After a landing, your cadence of step can restart so rise/run can change.  I can't think of a reason the nosing projections couldn't change too.  If you agree, please support this code change when you see it.  If you don't agree, then be a teacher and share with us why.  Thanks.


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## ADAguy (Jul 5, 2020)

Consider the potential change in handrail height that may occur at the changes in flights you proposal? If risers differ in height at each one then the handrail may develop waves if measured at each tread vs being consistent.


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## TheCommish (Jul 6, 2020)

A few Mass Editions ago the difference between rise and run of adjacent tread way limited to 3/16 of an inch, when we adopted the 2003 IBC the dimension changed to 3/8 overall tolerance.

I think 3/16 between stairs  should be the max and 3/8 over if flight then not 3/8 between adjacent treads

underline eddited


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## ADAguy (Jul 6, 2020)

So, as to measuring handrail height?


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## Paul Sweet (Jul 6, 2020)

R311.7.8.1 requires handrail height to be between 34" and 38".  It doesn't require the exact same height at each and every step.  I doubt that anybody would notice 3/16" difference between adjacent steps.

Come to think of it, a handrail that started at 34" above the first riser and increased to 38" above the last riser might comply!


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## ADAguy (Jul 6, 2020)

Not a chance! We disapproved one for that very reason, inconsistent height along its length.


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## steveray (Jul 6, 2020)

ADAguy said:


> Not a chance! We disapproved one for that very reason, inconsistent height along its length.



Don't think there is a code section for that...What if I step on a different part of the tread?

You have my support on the nosings Glenn!


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## TheCommish (Jul 6, 2020)

A handrail needs to be uniform height  of the nosing line of the treads


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## ADAguy (Jul 7, 2020)

And what if the heights differ within allowed maximums between risers?
Handrail can still be considered uniformly compliant?


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## TheCommish (Jul 7, 2020)

First, on inspections  I try not to take the tape measure out of the truck.  I have been doing this long enough that in most cases, looking, walking the stair and grasping the rails will tell me if  there are compliance issues.

If you wan to check for uniformity of star rise -run look from the top of the stair down the plane of  nosing, if you can get on line and see all the tip of the nosing the stair is uniform, handrails have a comfortable height in the allowed range .

Most often if the stair  if it is out of compliance is  real sloppy or it is the top or bottom tread that  is  out of compliance with the uniformity.

our building permit cards are 8.5 x 11 inches, a paper bill is 6 inches.

If I observe a condition that I feel is out of compliance or real close then the tape comes out. I do not expect machinist tolerance of wood the swells  and shrinks.

some days I don't even have to get out of the truck


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## Glenn (Jul 8, 2020)

In the IBC the handrail height has to be uniform.

In the IRC it does not.

I don't understand how a lack of uniform height is going to make me loose my grasp?  When I use stairs, my hand is moving in relation to my body, as my body is bobbing up and down with each step.


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## Rick18071 (Jul 8, 2020)

TheCommish said:


> First, on inspections I try not to take the tape measure out of the truck



I usually only use the tape measure for accessibility.


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## Inspector Gift (Jul 8, 2020)

Glenn said:


> Has anyone else noticed how the IRC only requires uniformity of riser height and tread depth in each single flight of stairs (can change after a landing).  However, the section for nosing projection uniformity(R311.7.5.3) states the requirement is for "stairways" (includes all flights on both sides of an intermediate landing).
> 
> I have already prepared a modification proposal for the 2024 IRC to change the nosing uniformity to "flight of stairs".  After a landing, your cadence of step can restart so rise/run can change.  I can't think of a reason the nosing projections couldn't change too.  If you agree, please support this code change when you see it.  If you don't agree, then be a teacher and share with us why.  Thanks.


 
For all practical purposes, we are only talking 1/8 inch difference.  Currently the tolerance for treads and risers is 3/8 inch in any given flight.  The maximum and minimum limits for nosings is 1-1/4 inch to 3/4 inch, which is 1/2 inch tolerance.   Since treads are measured from the projecting edge (nosing) to the upper most projection (nosing), the projection tolerance is no where close to being the trip hazard as the rise or run are.  

Case in point:   Your pics of your custom deck showed the top step riser did NOT have a nosing, yet all the other steps did have treads with nosings.  Yet your owners did not complain of a trip hazard, did they?   Because the tread dept was measured from the projection not the risers.  

I am content with leaving things as they are.


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## Inspector Gift (Jul 8, 2020)

TheCommish said:


> First, on inspections  I try not to take the tape measure out of the truck.  I have been doing this long enough that in most cases, looking, walking the stair and grasping the rails will tell me if  there are compliance issues.
> 
> If you wan to check for uniformity of star rise -run look from the top of the stair down the plane of  nosing, if you can get on line and see all the tip of the nosing the stair is uniform, handrails have a comfortable height in the allowed range .
> 
> ...



There are several corrections visible without even measuring.
1. Bottom riser is too short.
2. Open risers above treads over 30 inches above grade require guards limiting the space to less than 4 inches.
3. Lack of graspable handrail with an approved profile.
4. Bottom landing appears to be less than 36 inches in depth.


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## Glenn (Jul 8, 2020)

Inspector Gift said:


> For all practical purposes, we are only talking 1/8 inch difference.  Currently the tolerance for treads and risers is 3/8 inch in any given flight.  The maximum and minimum limits for nosings is 1-1/4 inch to 3/4 inch, which is 1/2 inch tolerance.   Since treads are measured from the projecting edge (nosing) to the upper most projection (nosing), the projection tolerance is no where close to being the trip hazard as the rise or run are.
> 
> Case in point:   Your pics of your custom deck showed the top step riser did NOT have a nosing, yet all the other steps did have treads with nosings.  Yet your owners did not complain of a trip hazard, did they?   Because the tread dept was measured from the projection not the risers.
> 
> I am content with leaving things as they are.


Good point about 3/8" variation in only 1/2" of space.  However, I still don't see the need for the inconsistency.  It's just a simple change, but it will make the codes appear to be more sensible.  When I teach this subject, I spend a lot of time talking about the science of using stairs.  I talk about what intermediate landings provide.  I talk about definitions of "stair" and "stairway".  Then when I get to the nosing projection uniformity, it all falls apart and I can't really justify the code.  So... a change from "stairway" to "flight of stairs" seems appropriate.  If the IRC is not sensible, the public will not trust it or our work to administer it.


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## ADAguy (Jul 9, 2020)

Inspector Gift said:


> For all practical purposes, we are only talking 1/8 inch difference.  Currently the tolerance for treads and risers is 3/8 inch in any given flight.  The maximum and minimum limits for nosings is 1-1/4 inch to 3/4 inch, which is 1/2 inch tolerance.   Since treads are measured from the projecting edge (nosing) to the upper most projection (nosing), the projection tolerance is no where close to being the trip hazard as the rise or run are.
> 
> hAZARD is the open risers.
> 
> ...


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## steveray (Jul 9, 2020)

I will usually tell them they are off and when they argue I ask them if they want me to go get my tape measure....I've got a pretty good eye. Walking with a job super on some temp school stairs and I told him the top rise was off by a 1/4 which was OK because 3/8 was allowed....Didn't believe me,He went and got his own tape. 1/4 it is...


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## Paul Sweet (Jul 9, 2020)

I once heard that medieval castles were sometimes built with a shorter top step which would cause invaders to stumble.  I don't know if this is true, or just an excuse for sloppy workmanship.


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## classicT (Jul 9, 2020)

Paul Sweet said:


> I once heard that medieval castles were sometimes built with a shorter top step which would cause invaders to stumble.  I don't know if this is true, or just an excuse for sloppy workmanship.


I do not have a definitive source on this, but I have heard the same many times before. A brief google search shows many hits with indication that this was true.

The other notable trait to medieval stairs it that most castle stairs rose in a clockwise spiral to allow the defender to retreat up the stairs and use the central column as a shield while the attacker was left exposed when attacking with a sword in the right hand. Some notable families with a preponderance of left-handedness would reverse to counter-clockwise.

From a website called All Things Medieval - "*The hidden secrets of Stairwells *– Stairwells were often very carefully designed in Medieval Castles. Stairwells that curved up to towers often curved very narrowly and in a clockwise direction. This meant that any attackers coming up the stairs had their sword hands (right hand) against the interior curve of the wall and this made it very difficult for them to swing their swords. Defenders had their sword hands on the outside wall, which meant they had more room to swing. Another ingenious design of stairs was that they were designed with very uneven steps. Some steps were tall and other steps were short. The inhabitants, being familiar with the uneven pattern of the stair heights could move quickly up and down the stairs but attackers, in a dimly lit stairwell, would easily fall and get bogged down in the stairwells. This made them vulnerable to attacks and slowed their attacks down significantly."​


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## Glenn (Jul 9, 2020)

Ty J. said:


> I do not have a definitive source on this, but I have heard the same many times before. A brief google search shows many hits with indication that this was true.
> 
> The other notable trait to medieval stairs it that most castle stairs rose in a clockwise spiral to allow the defender to retreat up the stairs and use the central column as a shield while the attacker was left exposed when attacking with a sword in the right hand. Some notable families with a preponderance of left-handedness would reverse to counter-clockwise.
> 
> From a website called All Things Medieval - "*The hidden secrets of Stairwells *– Stairwells were often very carefully designed in Medieval Castles. Stairwells that curved up to towers often curved very narrowly and in a clockwise direction. This meant that any attackers coming up the stairs had their sword hands (right hand) against the interior curve of the wall and this made it very difficult for them to swing their swords. Defenders had their sword hands on the outside wall, which meant they had more room to swing. Another ingenious design of stairs was that they were designed with very uneven steps. Some steps were tall and other steps were short. The inhabitants, being familiar with the uneven pattern of the stair heights could move quickly up and down the stairs but attackers, in a dimly lit stairwell, would easily fall and get bogged down in the stairwells. This made them vulnerable to attacks and slowed their attacks down significantly."​


OMG!!  As a code history fan I absolutely love this so much.  Did they write code books back then?  I mean... I have a Hammurabi code translation from 1904, so it's possible.

I also saw something recently about how the moats were designed to be sickening cesspools of disease.  The castle bathrooms drained to it.  It was a sanitary sewage defense system.


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## ADAguy (Jul 10, 2020)

Ty J. said:


> I do not have a definitive source on this, but I have heard the same many times before. A brief google search shows many hits with indication that this was true.
> 
> The other notable trait to medieval stairs it that most castle stairs rose in a clockwise spiral to allow the defender to retreat up the stairs and use the central column as a shield while the attacker was left exposed when attacking with a sword in the right hand. Some notable families with a preponderance of left-handedness would reverse to counter-clockwise.
> 
> From a website called All Things Medieval - "*The hidden secrets of Stairwells *– Stairwells were often very carefully designed in Medieval Castles. Stairwells that curved up to towers often curved very narrowly and in a clockwise direction. This meant that any attackers coming up the stairs had their sword hands (right hand) against the interior curve of the wall and this made it very difficult for them to swing their swords. Defenders had their sword hands on the outside wall, which meant they had more room to swing. Another ingenious design of stairs was that they were designed with very uneven steps. Some steps were tall and other steps were short. The inhabitants, being familiar with the uneven pattern of the stair heights could move quickly up and down the stairs but attackers, in a dimly lit stairwell, would easily fall and get bogged down in the stairwells. This made them vulnerable to attacks and slowed their attacks down significantly."​


Yes but how does that account for the lack of a handrail or rails in many cases?


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## e hilton (Jul 10, 2020)

ADAguy said:


> Yes but how does that account for the lack of a handrail or rails in many cases?


Cuz when you stab the attacker you want him to fall off the stairs onto the cardboard boxes like the Errol Flynn movies.


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## ADAguy (Jul 13, 2020)

"Cute"


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