CBC 420.2 Separation Walls for R-1 Hotel

[rjjh]

Hi!
I am trying to determine if a 1hr separation will be required between 65 separate single hotel sleeping units that are spaced 18ft apart from each other on a site, in addition to a central clubhouse 30ft away from all sleeping units. Per CBC 508.3.3 exception 2, R-1 sleeping units must be separated per 420.2, which states that:

Walls separating dwelling units in the same building, walls separating sleeping units in the same building and walls separating dwelling or sleeping units from other occupancies contiguous to them in the same building shall be constructed as fire partitions in accordance with Section 708.
So, would the sleeping units be considered the same building if mixed use non-separated (even though they are independent structures separated by 18ft)? and would a fire partition be required on the exterior walls?

See attached and additional project details:

• Single prefab sleeping units with exterior corrugated metal panel finish spread across a site
• Type IB construction
• R-1 occupancy
• mixed use non-separated per 508.3
• Single story, non-bearing exterior walls
• California CBC
• NFPA 13 sprinkler system
• 

Thank you for your help!

 

[classicT]

Are you treating these as separate buildings? If so, FSD applies. Looking at 1-hr rated exterior walls per Table 705.5. (FSD = 9-ft)

 

[classicT]

If treating these as one building, following Exception #1 to 705.3, then things get a bit murky. As a common wall is not shared, the application of 420.2 for separation walls is challenging. The walls between units provide separation between the unit and the exterior, not an adjoining unit. However, there is certainly some risk of fire exposure unit-to-unit.

2022 CBC 705.3 Buildings on the Same Lot​

For the purposes of determining the required wall and opening protection, projections and roof-covering requirements, buildings on the same lot shall be assumed to have an imaginary line between them.

Where a new building is to be erected on the same lot as an existing building, the location of the assumed imaginary line with relation to the existing building shall be such that the exterior wall and opening protection of the existing building meet the criteria as set forth in Sections 705.5 and 705.8.
Exceptions:

1. Two or more buildings on the same lot shall be either regulated as separate buildings or shall be considered as portions of one building if the aggregate area of such buildings is within the limits specified in Chapter 5 for a single building. Where the buildings contain different occupancy groups or are of different types of construction, the area shall be that allowed for the most restrictive occupancy or construction.
2. Where an S-2 parking garage of Construction Type I or IIA is erected on the same lot as a Group R-2 building, and there is no fire separation distance between these buildings, then the adjoining exterior walls between the buildings are permitted to have occupant use openings in accordance with Section 706.8. However, opening protectives in such openings shall only be required in the exterior wall of the S-2 parking garage, not in the exterior wall openings in the R-2 building, and these opening protectives in the exterior wall of the S-2 parking garage shall be not less than 11/2-hour fire protection rating.

2022 CBC 420.2 Separation Walls​

Walls separating dwelling units in the same building, walls separating sleeping units in the same building and walls separating dwelling or sleeping units from other occupancies contiguous to them in the same building shall be constructed as fire partitions in accordance with Section 708.

 

[rjjh]

thank you classicT.
That is the exact murkiness I am probably overthinking. Chapter 5 treats it as one building and 420.2 treats it as a single building implying a common wall. However, in actuality it will be multiple, non-separated buildings, spaced apart, without a common wall, but with sleeping units separated by 2 ideally non-rated metal walls.

 

[rjjh]

Looking further into the fire partitions (section 708) required by section 420.2, would I be correct interpreting section 708.5 as not requiring a rated assembly at these exterior walls?

708.5 Exterior Walls
Where exterior walls serve as a part of a required fire-resistance-rated separation, such walls shall comply with the requirements of Section 705 for exterior walls, and the fire-resistance-rated separation requirements shall not apply.
Exception: Exterior walls required to be fire-resistance rated in accordance with Section 1021.2 for exterior egress balconies, Section 1023.7 for interior exit stairways and ramps and Section 1027.6 for exterior exit stairways and ramps.