Occupancy separation

[ELLEN09US]

I'm changing the use of a tenant space from Group R to Group A-2. A fire sprinkler system will be installed, as the occupant load for the A-2 space is 180. The adjacent tenant space is Group B occupancy. The plan checker is requiring a 2-hour fire separation between the two occupancies, but based on my understanding, if a sprinkler system is provided, a 1-hour fire-resistance rating should be sufficient.


My second issue is with the wall detail. I proposed a 2-hour rated assembly with three layers of gypsum board on the A-2 side and one layer on the B occupancy side. However, the plan checker rejected this detail because it was based on UL design for metal studs, and the existing condition has wood studs.


I then submitted UL U336, but the plan checker stated that the gypsum board on the B occupancy side must specifically be Sheetrock® UltraLight, which seems overly restrictive. Additionally, we have no access to the adjacent tenant space, so we cannot apply any additional gypsum board on that side of the wall.


Could you please advise on a code-compliant solution using wood studs and a wall configuration that can be installed entirely from the A-2 side? The wall is long and tall, so I want to avoid adding a new wall with four layers of gypsum board on metal studs in addition to the existing wood stud wall.

 

[e hilton]

Will the sprinklers be on both sides?

 

[TheCommish]

The wall if required has to be build in accordance wiht the specific listing design, and in nay case has multiple options for the brand and type of wall covering. rock

 

[mtlogcabin]

Use an area separation wall design

https://www.buildgp.com/wp-content/uploads/2018/11/DensGlass-Shaftliner-area-walls-technical-guide.pdf

 

[Yankee Chronicler]

The fire-resistance rating is based on IBC Table 508.4 The first footnote states that 'S' means the building is sprinklered throughout. The question asked by e hilton is important. It sounds like you're trying to not do any work on the B side of the demising wall. If this means you are only adding sprinklers on the A-2 side, then the plan checker is correct -- you cannot use the fire-resistance ratings from the sprinklered columns.



You also can't mix and match components in U.L. assemblies. An assembly that was tested and listed with steel studs cannot be used with wood studs.

 

[TheCommish]

Side question, has an seen a listed shaft wall system that allows the shaft liners to be installed horizontally?

 

[mtlogcabin]

​

Footnote f sends you to 707.3.10 which also requires a 2 hr rating​

707.3.10 Fire areas.​

The fire barriers, fire walls, horizontal assemblies or combinations thereof separating a single occupancy into different fire areas shall have a fire-resistance rating of not less than that indicated in Table 707.3.10. The fire barriers, fire walls,horizontal assemblies or combinations thereof separating fire areas of mixed occupancies shall have a fire-resistance rating of not less than the highest value indicated in Table 707.3.10 for the occupancies under consideration.

 

[ELLEN09US]

Thank you all!