Does stair to penthouse need to meet headheight?

one of the BS ce questions indicates that stair to penthouse doesn’t need to meet 80" clear height req, but I couldn’t find any exception in IBC supporting it. Would someone clarify?


Hello @xurubi one of our expert architects will be able to clarify this question. @coachchrishopstock could you assist xurubi?

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Wondering what @coachdarionziegler thinks about this one?
I’ve already provided feedback to @xurubi on this one but would love to start up a discussion about it!

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Hi @xurubi & @coachchrishopstock ,

What a good question! You know, I had to look this up because I have never actually provided a stair to a penthouse or any other roof access before. I have only ever used ladders or an alternating tread device at best.

Without seeing the full context of the question I’m afraid I’m guessing a bit here, but my gut feeling is that perhaps the stair in question is not leading to an occupied roof? Per the exception to 1011.12 of the IBC a stairwell isn’t even required for non-occupied roofs.

I’m thinking what the question maybe is getting at is that typical head height and area requirements are not required for access to unoccupied spaces, including unoccupied roofs.
Additional, article 1510.2 discusses that penthouses have a maximum height. It doesn’t mention that they have a minimum height though…

However, I can’t find anything in the IBC that would make me think that this is absolutely allowed either. Typically, I would assume 80" head height at a stair to be required in all cases. Perhaps there is more context in the question I’m not seeing. Does this line up with what you were thinking @coachchrishopstock ?

it is from one of the BS CE question. i figured out that ibc chapter definition said penthouse is unoccupied space, and under stair chapter 1101 general indicate clearance /width therein is for occupied area.
it is a bit confusing though, we called penthouse unit in residential project and possibly others too .

Hey @coachdarionziegler thanks for your input!
My thought was similar to yours - this sounds like an unoccupied roof (since Penthouses are defined in the IBC as unoccupied mechanical spaces). I can think of some instances similar to this where an unoccupied mechanical space is provided with a way in and out that doesn’t necessarily comply with IBC egress requirements - the best example that comes to mind is MRL overhead spaces that are often accessed via hatches, as opposed to properly sized egress doors. Taking this logic further, I’d think that 80" headroom should definitely be a goal, but if conditions do not permit (such as what this question suggests) I’d think that this can be reduced.
Anyway, since this is a very nuanced and complicated topic, we’ve decided to replace this question on our exams with a better one. It was definitely interesting to discuss!