Separation Walls in Apartment Building

[ETThompson]

Hi

We're working on a mixed-use R-2 apartment project. It is a 3-story, approx. 12,000 sf project, Type VB construction, with an A-2 future/shelled restaurant at ground level and an amenity roof deck above. We're under the 2017 Ohio Building Code which is based on the 2015 IBC.

We have a condition where our apartments on one side abut the double-height restaurant space below, and the roof deck above. The roof deck is under 500sf / 50 occupants so classified as "B". The wall to the roof deck is (obviously) an exterior wall, and does not have a rating requirement.

We had shown the walls between these spaces as 708 Fire Partitions, based on 420.2. Therefore the open web wood trusses extend to and bear on the wall framing, and the rated wall assembly stops at the underside of the apartment floor/ceiling assembly (on the apartment side), and the underside of the rated roof deck assembly (on the restaurant/roof deck side). We're getting a permit comment from the building department stating that they think these need to be Fire Barriers per 508.4.4.1.

Wouldn't the more specific requirements in 420.2 override the general ones in 508.4.4.1? Which takes precedence and why? I've consulted the Commentary but couldn't find any guidance there either.

Thanks

 

[classicT]

420.2 provides a minimum requirement for fire partitions; however, due to the differing hazards associated with B and R-2 occupancies, increased protection is required in the form of fire barriers per 508.4.4.1. 420.1 (below) notes that compliance with other provisions is still required.

420.1 General

Occupancies in Groups I-1, R-1, R-2, R-3 and R-4 shall comply with the provisions of Sections 420.1 through 420.6 and other applicable provisions of this code.​

 

[ETThompson]

OK thanks.