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Measuring risers at thresholds

Mr. Inspector

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Poconos/eastern PA
I am curious if you count a threshold as part of the riser at a door or do you measure to the landing on the other side of the door. For a single step at a door I thought that you measured from the bottom landing to the top of the threshold with a maximum of 7". But reading 2018 IBC 1010.1.7 "Thresholds", exception 1, (for R-2 exterior door, non accessible, not a means of egress, the threshold can be 7-3/4 high which makes me think that I should only measure to the landing on the other side of the door since 1003.5.5 "Elevation Change", exception 1 requires a 7" max risers at R-2 non accessible exterior doors.

Unfortunately there is no definition of a riser in the IBC.

So is a threshold part of a riser or not when on top of a step?
 
For structures under the IRC, see the following. Take note that under these sections you do measure to the top of the threshold.

2021 IRC R311.3.1 Floor Elevations at the Required Egress Doors

Landings or finished floors at the required egress door shall be not more than 11/2 inches (38 mm) lower than the top of the threshold.
Exception: The landing or floor on the exterior side shall be not more than 7 3/4 inches (196 mm) below the top of the threshold provided that the door does not swing over the landing or floor.
Where exterior landings or floors serving the required egress door are not at grade, they shall be provided with access to grade by means of a ramp in accordance with Section R311.8 or a stairway in accordance with Section R311.7.

2021 IRC R311.3.2 Floor Elevations at Other Exterior Doors

Doors other than the required egress door shall be provided with landings or floors not more than 7 3/4 inches (196 mm) below the top of the threshold.
Exception: A top landing is not required where a stairway of not more than two risers is located on the exterior side of the door, provided that the door does not swing over the stairway.

Now, regarding structures under the IBC, I agree that you can start at Section 1003.5 - which points to Section 1010.1.4. Section 1010.1.4 basically requires no step; however, as identified by the OP, Exception #1 can apply (so can #3).

1010.1.4, Exception #1 - At doors serving individual dwelling units or sleeping units in Groups R-2 and R-3 : a door is permitted to open at the top step of an interior flight of stairs, provided that the door does not swing over the top step.​
1010.1.4, Exception #3 - At exterior doors serving Group U and individual dwelling units and sleeping units in Groups R-2 and R-3, and where such units are not required to be Accessible units, Type A units or Type B units, the landing at an exterior doorway shall be not more than 7 3/4 inches (197 mm) below the landing on the egress side of the door. Such doors, including storm or screen doors, shall be permitted to swing over either landing.​

Exception #1 would be limited to an interior flight of stairs and would allow for no landing; it however, does not address riser height. Given that this is intended for interior flight of stairs, there really should not be any threshold.

Exception #3 is again silent on threshold, but is probably a more applicable reference to the question at hand.

All of that aside, look to Section 1010.1.6 and see Exception #1. From here, I think it is generally clear that you measure to the top of the threshold just as done in the IRC. Again, you do measure to the top of the threshold.

1010.1.6 Thresholds

Thresholds at doorways shall not exceed 3/4 inch (19.1 mm) in height above the finished floor or landing for sliding doors serving dwelling units or 1/2 inch (12.7 mm) above the finished floor or landing for other doors. Raised thresholds and floor level changes greater than 1/4 inch (6.4 mm) at doorways shall be beveled with a slope not greater than one unit vertical in two units horizontal (50-percent slope).
Exceptions:
  1. In occupancy Group R-2 or R-3, threshold heights for sliding and side-hinged exterior doors shall be permitted to be up to 7 3/4 inches (197 mm) in height if all of the following apply:
    1. The door is not part of the required means of egress.
    2. The door is not part of an accessible route as required by Chapter 11.
    3. The door is not part of an Accessible unit, Type A unit or Type B unit.
  2. In Type B units, where Exception 5 to Section 1010.1.4 permits a 4-inch (102 mm) elevation change at the door, the threshold height on the exterior side of the door shall not exceed 4 3/4 inches (120 mm) in height above the exterior deck, patio or balcony for sliding doors or 4 1/2 inches (114 mm) above the exterior deck, patio or balcony for other doors.
 
Classic T is in the right Section, but PA as adopted see sections 1010.1.5 Floor elevation, section 1010.1.6 Landings at doors, and section 1010.1.7 Thresholds

In 101.1.5, exceptions and note that #3 tags in the full height the same as the IRC at 7.75" counting the threshold.

in 1010.1.7 it is simple the threshold needs to be sloped meeting run and rise requirements, and the landings/floors need to be the same height on each side

Additionally, exception 1 again points to the 7.75" maximum for R-2 & R-3's counting the threshold.

So, in the IBC the floors are the same in elevation based on the allowed pitch/slope being the only difference and the threshold is nothing more than a speed bump on the walking surface meeting certain requirements, as for the residential exception, the threshold is counted as part of the total rise.

At least that is how I have always simplified the explanation.
 
Thanks classicT and tbz but the language in the 2021 and 2018 IBC seems a lot different. I found out this project was permitted under 2015 IBC.

I think I'll use 1010.1.7 which says thresholds at swinging doorways shall not exceed 1/2 above the finished floor or landing for swinging doors.
1002.5 exception1 allows a single 7" step for R-2 occupancies.
So the total rise can not not be more then 7-1/2" from the bottom landing to the top of the threshold for these egress, non accessible doors. Does not say anything about which way the door swings.
 
If If there is no stairway, there is no riser. If there is only a landing on each side of the threshold there is no riser and the difference in elevation can be 7.75" (with conditions).

RB STAIRWAY. One or more flights of stairs, either interior or exterior, with the necessary landings and connecting platforms to form a continuous and uninterrupted passage from one level to another within or attached to a building, porch or deck.

RB FLIGHT. A continuous run of rectangular treads or winders or combination thereof from one landing to another.

RB RISER (STAIR). The vertical component of a step or stair.

RB STAIR. A change in elevation, consisting of one or more risers.
 
If If there is no stairway, there is no riser. If there is only a landing on each side of the threshold there is no riser and the difference in elevation can be 7.75" (with conditions).
If there is any elevation difference, it must be minimum 4", and then you have a stair with a riser, by the definitions, correct?
 
I only have an outdated version of the CRC based on the 2019 CRC and 2018 IRC®....so there might now be a 4" minimum. riser height.

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. At open risers, openings located more than 30 inches (762 mm), as measured vertically, to the floor or grade below shall not permit the passage of a 4-inch-diameter (102 mm) sphere.

In the residential code, a stair is a change of elevation but not every change in elevation is a stair. With no stair there is no riser.

The building code has this:
RISER. The upright part between two adjacent stair treads, between either an upper or lower landing and an adjacent stair tread, or between two adjacent landings.

1011.5.2 Riser height and tread depth. Stair riser heights shall be 7 inches (178 mm) maximum and 4 inches (102 mm) minimum.

[BE] STAIR. A change in elevation, consisting of one or more risers
 
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In the residential code, a stair is a change of elevation but not every change in elevation is a stair. With no stair there is no riser.
A ramp? I do consider this about changes of elevations that an occupant would traverse, though I suppose some might traverse from a second floor balcony to first floor.

If in walking through the area you have to step up or down, and not a ramp, pretty sure it's a stair with one riser.

RB STAIR. A change in elevation, consisting of one or more risers.
 
R RISER (STAIR). The vertical component of a step or stair. 

R STAIR. A change in elevation, consisting of one or more risers.

It's sorta like a dog chasing it's tail. Note that the definition of RISER is clarified with (STAIR).... However, step and stair are not identical.

Can you think of any elevation changes in a dwelling that would be problematic if found to be a stair? If all changes in elevation are a stair I have fireplace thresholds that are not illuminated with a light fixture controlled by a wall switch. Granted the elevation change is 2" but it sticks away from the wall and people stand on it. Is the intent to be literal and have the dog finally score.

There are a great many homes with a change of elevation that cuts across an entire room....is that a stair?


There is no mention of a riser in 311.3.1

R311.3.1 Floor elevations at the required egress doors.
Landings or finished floors at the required egress door shall be not more than 11/2 inches (38 mm) lower than the top of the threshold.
Exception: The landing or floor on the exterior side shall be not more than 73/4 inches (196 mm) below the top of the threshold provided that the door does not swing over the landing or floor.
Where exterior landings or floors serving the required egress door are not at grade, they shall be provided with access to grade by means of a ramp in accordance with Section R311.8 or a stairway in accordance with Section R311
 
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If all changes in elevation are a stair I have fireplace thresholds that are not illuminated with a light fixture controlled by a wall switch.
Unless you're Santa, that's not an m.o.e. normally. And I believe stairs and their parts are only regulated as m.o.e.

There are a great many homes with a change of elevation that cuts across an entire room....is that a stair?
If it's in the m.o.e. yes. And they're a big hazard with much carnage and if permitted should be treated like a stair.
 
R311.3.2 Floor elevations at other exterior doors.
Doors other than the required egress door shall be provided with landings or floors not more than 73/4 inches (196 mm) below the top of the threshold.
Exception: A top landing is not required where a stairway of not more than two risers is located on the exterior side of the door, provided that the door does not swing over the stairway.

This is proof that a stairway can have a single riser.

RB STAIRWAY. One or more flights of stairs, either interior or exterior, with the necessary landings and connecting platforms to form a continuous and uninterrupted passage from one level to another within or attached to a building, porch or deck.
This is proof that a stairway has at a minimum, one flight.

RB FLIGHT. A continuous run of rectangular treads or winders or combination thereof from one landing to another.
This is proof that a flight has a tread which separates one landing from another.

RB RISER (STAIR). The vertical component of a step or stair.

RB STAIR. A change in elevation, consisting of one or more risers.


So the arguement is that the elevation change from the dwelling floor to the exterior landing is a stair. I have established that a single riser stair is also a stairway.

R311.7 Stairways.
R311.7.1 Width. Stairways shall be not less than 36 inches (914 mm) in clear width at all points above the permitted handrail height and below the required headroom height. The clear width of stairways at and below the handrail height, including treads and landings, shall be not less than 311/2 inches (787 mm) where a handrail is installed on one side and 27 inches (698 mm) where handrails are installed on both sides.


Now all of the sudden the doorway with it's stairway can be 31.5" wide. Sounds stupid right? A stairway can have a single riser. If the elevation change at the door between landings is a single stair riser well then.... you have a stairway.

That's why there is no mention of a riser in 311.3.1

R311.3.1 Floor elevations at the required egress doors.
Landings or finished floors at the required egress door shall be not more than 11/2 inches (38 mm) lower than the top of the threshold.
Exception: The landing or floor on the exterior side shall be not more than 73/4 inches (196 mm) below the top of the threshold provided that the door does not swing over the landing or floor.


There is a floor and a landing with no treads in between. No flight. No stairway. No riser.


 
R311.3.2 Floor elevations at other exterior doors.
Doors other than the required egress door shall be provided with landings or floors not more than 73/4 inches (196 mm) below the top of the threshold.
Exception: A top landing is not required where a stairway of not more than two risers is located on the exterior side of the door, provided that the door does not swing over the stairway.

This is proof that a stairway can have a single riser.
Not logically. If a stairway has to have 2 or more risers, it's still fine to refer to a "stairway of not more than two risers." It would just have the same meaning as "a stairway of exactly two risers." So the language choice is perhaps suggestive, just not definitive.
RB FLIGHT. A continuous run of rectangular treads or winders or combination thereof from one landing to another.
This is proof that a flight has a tread which separates one landing from another.
This is where I lost you. If a flight has to have a tread, and a tread is not a landing, and there's a landing on each end, then there has to be two risers in the flight. If there's only one riser, you just have two landings, no treads.
So the arguement is that the elevation change from the dwelling floor to the exterior landing is a stair.
Yes.

R311.3.1 Floor elevations at the required egress doors.
Landings or finished floors at the required egress door shall be not more than 11/2 inches (38 mm) lower than the top of the threshold.
Exception: The landing or floor on the exterior side shall be not more than 73/4 inches (196 mm) below the top of the threshold provided that the door does not swing over the landing or floor.


There is a floor and a landing with no treads in between. No flight. No stairway. No riser.
Are you trying to make the distinction between a floor and a landing? I.e. two landings = stairway, while a landing and a floor does not? The way the above always uses the phrase "landing or floor" makes me think it is more logical to treat to treat them interchangeably for the purposes of that section.

So I'm still in the "riser = any discrete change in elevation" (excludes ramps) and "stairway = two or more risers" camp.

Cheers, Wayne
 
A stairway can have a single riser. If the elevation change at the door between landings is a single stair riser well then.... you have a stairway.
A stair, not a stairway, can have a single riser by your code cut and pasted. A stairway is a flight, with more than riser.
 
I was asking about a R-2 non accessible exterior means of egress door to a deck in the 1015 IBC.

So if the max. 7-1/2 step up from the deck to the threshold top is a change of elevation and not a stairway or a riser but a just a floor on the bottom and top but no landings or treads and does not matter which way the door swings this would be allowed per the following two sections:

1010.1.7 Thresholds. Thresholds at doorways shall not
exceed 3/4 inch (19.1 mm) in height above the finished
floor or landing for sliding doors serving dwelling units or
1/2 inch (12.7 mm) above the finished floor or landing for
other doors. Raised thresholds and floor level changes
greater than 1/4 inch (6.4 mm) at doorways shall be beveled
with a slope not greater than one unit vertical in two units
horizontal (50-percent slope).
Exceptions:
1. In occupancy Group R-2 or R-3, threshold
heights for sliding and side-hinged exterior doors
shall be permitted to be up to 73/4 inches (197
mm) in height if all of the following apply:
1.1. The door is not part of the required means
of egress.
1.2. The door is not part of an accessible route
as required by Chapter 11.
1.3. The door is not part of an Accessible unit,
Type A unit or Type B unit.

Notice exception 1 is not calling it a elevation rise, or a stair or a riser but just a threshold height. But I can't use this because what I am looking at is a m.o.e

1003.5 Elevation change. Where changes in elevation of less
than 12 inches (305 mm) exist in the means of egress, sloped
surfaces shall be used. Where the slope is greater than one
unit vertical in 20 units horizontal (5-percent slope), ramps
complying with Section 1012 shall be used. Where the difference
in elevation is 6 inches (152 mm) or less, the ramp shall
be equipped with either handrails or floor finish materials
that contrast with adjacent floor finish materials.
Exceptions:
1. A single step with a maximum riser height of 7
inches (178 mm) is permitted for buildings with
occupancies in Groups F, H, R-2, R-3, S and U at
exterior doors not required to be accessible by
Chapter 11.
2. A stair with a single riser or with two risers and a
tread is permitted at locations not required to be
accessible by Chapter 11 where the risers and treads
comply with Section 1011.5, the minimum depth of
the tread is 13 inches (330 mm) and not less than
one handrail complying with Section 1014 is provided
within 30 inches (762 mm) of the centerline of
the normal path of egress travel on the stair.

No mention of which way the door swings anywhere here.

Notice that exception 1 is calling it a step, not a stair but is still calling for a riser, and 2 is calling it a stair with a single riser. I find this very confusing.
 
The commentary refers to "the required egress door". Does the mean other non-required egress doors dont have to comply? A 10" rise with outswinging door is ok?
I have been waiting for this thread to get to this question. I have struggled with the IRC language. I have not permitted doors to swing over any stair but specific to this thread I am talking about the "other" exterior door based on the following:

R311.3: a landing is required on each side of an exterior door.
R311.3.2: (subsection to R311.3) the floor or landing is permitted to be 7 3/4" below the threshold (does not stipulate which side of the door)
exc. to 311.3.2: a top landing is not required as long as the exterior side of the door has a stair 2 risers or less and the door doesn't swing over them.

I struggle because landing is not defined as a clear space without a door, though that is the way I have interpreted it. I also struggle because although the exception clearly indicates that it is the exterior landing that can be 7 3/4" below, it is not specified in the code itself, and says that the top landing is not required (Which is where I get the interpretation that the landing can't have a door in it.)

It seems like better language could be written, or maybe a definition for landing. I'll chew on this one....again.

I recently volunteered to do a review for a rather complicated residential addition. It showed 3 outswing doors, all over a single step, down to a patio. I haven't heard back from them yet, so this topic is timely.
 
Sifu - I think it's just a poor choice of words in the commentary. My opinion. My remark was nearly rhetorical. I support the ICC by membership and committee membership and being involved in the CDP, but I support NFPA likewise. As far as great clarity and editing of their documents, NFPA wins hands down. I was surprised when as a committee person I learned ICC doesn't even have a manual of style to guide the writing. Further surprised by commentary opinions contrary to the substantiation and committee statements for that section. I need to start reading commentaries and submitting comments for corrections (within my very small area if expertise - assembly seating and stages). NFPA staff has reached out to me for their handbook in these areas.

Not often a grumpy old man but can be at times.
 
Sifu - I think it's just a poor choice of words in the commentary. My opinion. My remark was nearly rhetorical. I support the ICC by membership and committee membership and being involved in the CDP, but I support NFPA likewise. As far as great clarity and editing of their documents, NFPA wins hands down. I was surprised when as a committee person I learned ICC doesn't even have a manual of style to guide the writing. Further surprised by commentary opinions contrary to the substantiation and committee statements for that section. I need to start reading commentaries and submitting comments for corrections (within my very small area if expertise - assembly seating and stages). NFPA staff has reached out to me for their handbook in these areas.

Not often a grumpy old man but can be at times.
I took it the way you intended, but I think it reflects my confusion with the way the code is written. From a practical standpoint, having tripped my fair share of times, opening a door over a step down is not a great thing. However, from a comment writing perspective and giving a specific citation it gets more difficult to substantiate.

For example, I can write a comment with a code reference that says to provide a landing on both sides of a door, but landing is not defined. I can't write a comment to not swing a door over a step down without first observing that a (undefined) landing at the top has not been provided. My recent comment regarding a condition where an outswing door was observed swinging over a step down to a patio (non-req. egress door) went something like this: Provide a landing at each side of the door in accordance with R311.3. An exception is provided to permit not having a top landing only where the door does not swing over the step per IRC 311.3.2. It would seem easier to just provide a definition for landing and/or saying that a door can't swing over a step. I haven't had to visit this condition in a long time, so maybe I am missing or forgetting a more simple way to skin that cat.
 
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