single egress from a roof deck

[RIS]

I am looking for some feed back on using code section 1006.2.1 to allow a single egress from a roof deck per section 1006.3.3 exception #2.

the roof deck is loaded at 48 occupant, so per table 1006.2.1 we should able to have one exit.

However, a reviewer has directed us to the following text from the commentary and told us that one exits from a roof deck is not allow unless on the level of egress with no vertical travel. "Section 1006.2.1 is intended to be applicable to rooms and spaces on a story, but not to an entire story level. One of the main concerns has been that vertical travel takes longer than horizontal travel in emergency exiting situations. However, if the space can exit directly to the exterior rather than egress into an interior corridor or an exit stairway, a higher level of safety is provided”

Curious to hear some thoughts on this...

 

[classicT]

Commentary is not code!

I'm not sure that I agree with the code section referenced. However, I would point to Table 1006.3.3(2) and indicate that a second story above grade plane for a Group B (assuming B given OL<50) is limited to a maximum occupant load per story of 29 where provided with a single exit. If this is a third story or higher, then a single exit is not even permitted.

Given you are indicating an occupant load of 48, I do not see a single exit as being viable.

 

[classicT]

And keep in mind that the Condition #2 of 1006.3.3, which points to 1006.2.1, requires that the area be provided with an exit that discharges directly to the exterior at the level of exit discharge.

Given that this space is on a roof, I presume it is not on the level of exit discharge. Therefore, there must be a stairway that is providing either exit access or serves as the exit.

 

[MADrkTEK]

If you have a stair tower that is providing you an exit at the roof level (door entering the stair tower)
that leads to and discharges directly to the exterior (does not re-enter the building from the stair tower on any level)
at the level of exit discharge (ground floor or level that meets the definition of exit discharge that provides unobstructed access to a public way)
then you do comply with exception two.

EXCEPTION 2. text:
"Rooms, areas and spaces complying with Section 1006.2.1 with exits that discharge directly to the exterior at the level of exit discharge, are permitted to have one exit or access to a single exit."

i believe the reviewer’s interpretation of the commentary text may be incorrectly applied (unless you are proposing to change levels before accessing the exit): the commentary’s reference to vertical exit (access) travel is intended to be in reference to the use of exit access stairways, which are not exits like stair towers are. The allowed use of exit access stairways for vertical exit access travel is limited to what is stated under 1006.3.1, which doesn’t include a B use. However, as I describe above: a rated stair tower is an exit. So if you can provide that exit at the same level as the occupied roof, and within the maximum common path of egress travel allowed for a single exit and your occupancy load (and you comply with 1006.2.1), then yes you should be in compliance with the IBC.