2012 IEBC - stairway enclosure requirements

[Tim Mailloux]

I am running into a conflict in the 2012 IEBC and could use some input from the members here. Level 2 alteration in a historic building, no change of use.


Section 803.2.1 Existing Vertical Openings, states that all existing interior vertical openings connecting two or more floors must be enclosed with a 1 hour rated enclosure. Exception 5.1 states that the enclosure is not required in Group B occupancy where no floor plate exceeds 3000SF. For this particular project exception 5.1 seems to apply to this project and we do not need to enclose the existing stairs. Good new! We don’t want to enclose them as the building is a historic mansion used as office space and enclosing the stairs would ruin the look and feel of the building.


But on the next page section 803.2.3 Supplemental Stairway Enclosure Requirements state that where the work area exceeds 50% of the floor area, stairways that are part of the means of egress serving the work area shall at a minimum be enclosed with smoke tight construction on the highest work area floor and all floors below. This section also seems to apply with the project conditions.



Which section takes priority? My opinion is that 803.2.3 is more specific than 803.2.1 and would take precedence, and the existing stairs need to be enclosed.

 

[cda]

How many stories is the building overall??

How many floors are open to each other?

 

[RLGA]

If the building is historic, then Chapter 12 could also be used. Section 1203.6 requires an enclosure similar to 803.2.3. So, either way, it sounds like you’ll have to enclose the stairway.

I agree that between the two sections you mentioned, Section 803.2.3 is more specific and would be applicable if the work area exceeds 50% of the floor area. However, the requirement has an exception, which allows unenclosed stairways if permitted by the IBC. Therefore, if the building is sprinklered, you might want to look at IBC Section 1009.3, Exception 3, which allows unenclosed stairways with draft curtains.

 

[Tim Mailloux]

I forgot to mention this project is located in CT, our state amendments to the 2012 IBC do no allow for unenclosed exit access stairs to be used as a means of egress. Egress stairs have to be enclosed, so that exception does nothing for me.

 

[steveray]

Smoke tight does not = fire rated...."smoke tight" it is....Note it is note smoke barrier which would be 1hr...