Communicating Stair

[Nicole Brooks]

Existing, type IIA construction, 5 story office building. Floors and supporting structure are rated an hour, Building is fully sprinklered. Walls between corridors and suites are not rated. Tenant has suits on 2nd and 3rd floor that they want to join with an open stair. By cutting through the floor, would I need to rate the interior perimeter walls of the suite an hour or are they fine as-is (unrated).

 

[RLGA]

See Section 712.1.9.

 

[Nicole Brooks]

See Section 712.1.9.

I have reviewed that section. I'm not quite sure I understand it. The only item that would apply in this case is number 2. Does not penetrate a horizontal assembly that separates fire areas or smoke barriers that separate smoke compartments. My understanding: I am penetrating a horizontal assembly (1hr rated floor). Definition of Fire Area: The aggerate floor area enclosed and bounded by fire walls, fire barriers, exterior walls, or horizontal assemblies of a building. So yes I am penetrating a horizontal assembly that separates a fire area. Now does this fire area separate smoke compartments? My understanding is that smoke compartments are required in some cases for ambulatory care, and I2 and I3 uses and for unprotected areas of refuge. Am I reading the wording wrong. Is what it's saying : Does not penetrate a horizontal assembly that separates fire areas or does not penetrate a smoke barrier that separates a smoke compartment? I've read the commentary, and it seems to apply only to I2 and I3, just want to confirm?

 

[RLGA]

I have reviewed that section. I'm not quite sure I understand it. The only item that would apply in this case is number 2. Does not penetrate a horizontal assembly that separates fire areas or smoke barriers that separate smoke compartments. My understanding: I am penetrating a horizontal assembly (1hr rated floor). Definition of Fire Area: The aggerate floor area enclosed and bounded by fire walls, fire barriers, exterior walls, or horizontal assemblies of a building. So yes I am penetrating a horizontal assembly that separates a fire area. Now does this fire area separate smoke compartments? My understanding is that smoke compartments are required in some cases for ambulatory care, and I2 and I3 uses and for unprotected areas of refuge. Am I reading the wording wrong. Is what it's saying : Does not penetrate a horizontal assembly that separates fire areas or does not penetrate a smoke barrier that separates a smoke compartment? I've read the commentary, and it seems to apply only to I2 and I3, just want to confirm?

Regarding #2, is the fire area relevant? Fire areas are mainly used to determine fire sprinkler protection requirements. Since your building is sprinklered throughout, the fire area concern is a moot issue.

If the restriction on fire area size was an issue, then the fire-resistive assemblies that separate the fire areas must meet certain fire-resistance ratings (See Table 707.3.10). Those assemblies being present in your building do not necessarily mean they qualify as a separation between fire areas.