Door Threshold size

[VAC]

Hi,
I'm aware of door threshold requirements as far as height (1/2"), beveled slope (1:12) etc.
Is there a min. or max threshold width/depth?
Existing commercial building. Looking at options to replace the existing 2" thresholds.
Never really paid attention to the widths of these things but the question came up today.
Looking for code requirements before flipping a coin

Thanks!

 

[e hilton]

They are usually the same as the wall thickness.

 

[steveray]

I'd say no......Do you have a particular concern?

 

[Yikes]

2010 ADAS (and codes based on it, such as CBC 11B) 404.2.4.4 say that no changes in level are permitted other than at thresholds and a max 1:48 slope; however, it does not mention a width of the level portions of the thresholds.








The code does not have a specific definition "threshold". Most of us assume it is probably not much deeper than the opening that the door frame sits in.
Most of us assume that the threshold is high in the middle/flat area as compared to the floor on either side of it, or at most it is the same level as one floor next to it.
However, it appears from the way the code is written that nothing theoretically prevents the threshold from having a rise on both sides of the threshold:



UPDATE: I realized that 404.2.5 is specific to allowing "RAISED thresholds". So I suppose in the illustration above, the right side might not be considered "raised"...?

One code oddity / loophole if you are NOT at a door, but are just along a general path of travel:
With no minimum horizontal distance specified between changes in levels, the way 302 and 303 are worded you could theoretically stack a whole bunch of 1/4" vertical changes in level very close to each other that would look like a set of micro-stairs (1/4" rise, 1/4" run) creating what functions like a 45 degree slope. But they aren't stairs, they're code compliant changes in level. Of course I would not want to do that in real life. But it does point up the limitations of code language in trying to cover all possible situations.

 

[north star]

@ @ + @ @

VAC, ...while there may not be any specific Code language or requirements
about widths, as you already know, the intent is to not have a threshold
that exceeds the Accessibility requirements, and to provide a smooth
transition from one side of the door to the other..........Then there is the
view of some about aesthetics and how the threshold matches the other
door components in the building.........Typically, a threshold probably
would not look the best if it extended too far from either side of the
door frame when installed [ i.e. - it would knock the building Feng Shui
out of balance ].

My recommendation, ...flip the coin, find a good, durable, metal threshold
that matches or somewhat matches the door frame and go with that.
If the "powers-that-be" don't like your choice, I'm sure that they will let
you know just badly you messed up and what a poor choice of thresholds
you made.

+ = @ + +

 

[VAC]

2010 ADAS (and codes based on it, such as CBC 11B) 404.2.4.4 say that no changes in level are permitted other than at thresholds and a max 1:48 slope; however, it does not mention a width of the level portions of the thresholds.

View attachment 11081

View attachment 11079


View attachment 11080

The code does not have a specific definition "threshold". Most of us assume it is probably not much deeper than the opening that the door frame sits in.
Most of us assume that the threshold is high in the middle/flat area as compared to the floor on either side of it, or at most it is the same level as one floor next to it.
However, it appears from the way the code is written that nothing theoretically prevents the threshold from having a rise on both sides of the threshold:

View attachment 11083

UPDATE: I realized that 404.2.5 is specific to allowing "RAISED thresholds". So I suppose in the illustration above, the right side might not be considered "raised"...?

One code oddity / loophole if you are NOT at a door, but are just along a general path of travel:
With no minimum horizontal distance specified between changes in levels, the way 302 and 303 are worded you could theoretically stack a whole bunch of 1/4" vertical changes in level very close to each other that would look like a set of micro-stairs (1/4" rise, 1/4" run) creating what functions like a 45 degree slope. But they aren't stairs, they're code compliant changes in level. Of course I would not want to do that in real life. But it does point up the limitations of code language in trying to cover all possible situations.

Thank you so much for your detailed reply! This answers my question.
The question we had was if we had to replace the thresholds we had or if we just bevel them onsite. They are only 2" 'wide' so if we bevel, they would technically only have 1" of flat section. (where the ? mark in red is). But it appears that even with its language limitation, there is no minimum (or max for that matter). I think the onsite solution would be a little silly looking as the flat part would be less than the width of the door itself. But I wanted to make sure I understood the code correctly and wasn't missing an important part.

Thank you!!

 

[VAC]

@ @ + @ @

VAC, ...while there may not be any specific Code language or requirements,
as you already know, the intent is to not have a threshold that exceeds
the Accessibility requirements, and to provide a smooth transition from
one side of the door to the other..........Then there is the view of some
about aesthetics and how the threshold matches the other door components
in the building.........Typically, a threshold probably would not look the best
if it extended too far from either side of the door frame when installed
[ i.e. - it would knock the Feng Shui out of balance ].

My recommendation, ...flip the coin, find a good, durable, metal threshold
that matches or somewhat matches the door frame and go with that.
If the "powers-that-be" don't like your choice, I'm sure that they will let
you know just badly you messed up and what a poor choice of thresholds
you made.

+ = @ + +

I like the way you think!
Yes, after reading all the super helpful answers I'll just offer a solution that in the long run will look best. A super skinny threshold would not look right. I understand I may be overruled, but at least I'll know I tried

 

[north star]

# # = # #

# # = # #

 

[VAC]

I'd say no......Do you have a particular concern?

I wasn't sure if there was a minimum size threshold that could be beveled... but I'm just going to recommend replacing existing (which is only 2" -and once beveled it will only have 1" in the middle -flat portion). I always just do new when needed and don't give it a second thought.

 

[steveray]

I wasn't sure if there was a minimum size threshold that could be beveled... but I'm just going to recommend replacing existing (which is only 2" -and once beveled it will only have 1" in the middle -flat portion). I always just do new when needed and don't give it a second thought.

If it is fire rated maybe required to be the width/ thickness of the door at least, but I would have to look in NFPA 80....

 

[VAC]

If it is fire rated maybe required to be the width/ thickness of the door at least, but I would have to look in NFPA 80....

ahhh, but of course!!
A couple of doors are, so most definitely would need to look into that.
Thank you!!