How to measure door opening height? To threshold?

[Yikes]

IBC 1010.1 says: "The minimum CLEAR OPENING HEIGHT of doors shall not be less than 80 inches."
If my door has a threshold, does the phrase CLEAR OPENING HEIGHT mean I must measure the 80 inches from the bottom of the head to the top of the threshold? If "yes", then most of the standard 80" doors I've installed with a threshold would not comply.

There is an exception in 1010.1.1.1 that allows door closers and door stops to encroach down to 78" above finish floor. But there is nothing in this section that says a threshold is also an allowable encroachment into the required height.

 

[Yankee Chronicler]

I don't think the code specifies how/where to measure clear opening height, but for clear opening width the IBC is clear that it's measured from the face of the door when open 90 degrees to the face of the door stop on the latch jamb, so I would say for height it's from the highest point of the threshold to the lowest edge of the stop along the top of the door frame.

That said, in all the years I've been preparing construction documents and reviewing construction documents, I've never even though about this. I've always gone by the nominal size of the door for height. (But I do base the egress capacity of a 3-foot door on the basis of a fairly typical 33-inch clear width unless there's very convincing documentation that they can magically provide more than that.)

 

[Yikes]

I don't think the code specifies how/where to measure clear opening height, but for clear opening width the IBC is clear that it's measured from the face of the door when open 90 degrees to the face of the door stop on the latch jamb, so I would say for height it's from the highest point of the threshold to the lowest edge of the stop along the top of the door frame.

I hear you, and that’s how I read the words “clear opening height”, but that means that every typical 80” door with a threshold is noncompliant, right?

 

[walker.t]

I don't think the code specifies how/where to measure clear opening height

A117.1 does not consistently state the reference points for measurements in this provision:

A117.1-2017 307.4 Vertical Distance [editorial comments in bold]
Vertical clearance shall be 80” minimum [above what?]. Rails or other barriers shall be provided where the vertical clearance is less than 80” [above what?]. The leading edge of such rails or barrier shall be located 27” maximum above the floor [thank you for clearly stating the reference point, that’s kind of important].
Exception: Door closers and door stops shall be permitted to be 78” minimum above the floor [thank you for telling us where to put the end of the tape measure].

does the phrase CLEAR OPENING HEIGHT mean I must measure the 80 inches from the bottom of the head to the top of the threshold?

In light of A117.1-2017 307.4 Exception, I’d say as long as the bottom of the door head is 78” above the floor that you have met the requirement, the door threshold is not the floor. Threshold would of course have to meet the requirements of A117.1-2017 404.2.4.

 

[SCBO1]

but that means that every typical 80” door with a threshold is noncompliant, right?

Yes an 80" door would most likely be non-compliant but doors are typically not 80", they are around 79-1/8", so measure to the top of the door threshold to the underside of the door head jamb, should have 80".

 

[SCBO1]

My commercial steel door in my office measured 83-1/4.

 

[Yikes]

SCB01, here's a typical prehung residential exterior door from build.com. 36"x80" nominal is a standard size in multifamily residential.
https://www.build.com/trimlite-3068lhisp-her2033c69161db/s1755824?uid=4147880&searchId=fhHQzQMW0z
It shows the door panel being 79" high. That leave's maybe 1/8 to 1/4" at the top and about 3/4" at the bottom. The bottom presumably has a threshold so that there's not a huge exposed undercut to let outside weather into the interior of the building.

That threshold would mean NET CLEAR opening is less than 80", if you are measuring to top of threshold. That means most of the residential doors sold in America today would not comply with that definition of "net clear".