Yikes
Gold Member
2-story, Type V-A (1 hour) wood-framed apartment building, sprinklered per NFPA 13R. The 18 units are “flats”, meaning that the upstairs and downstairs are two separate (stacking) units.
I want to run the 7” dia. range hood and bathroom exhaust fan ducts from the first floor across through (1) a horizontal nonrated gyp board soffit below the rated floor-ceiling assembly, then up (2) penetrating the 1 hour floor-ceiling assembly, then (3) through a nonrated furred gyp board wall in the back of a closet in the 2nd floor unit, then finally (4) through the 1-hour roof assembly. The ducts run individually, and do not open into the second floor unit.
Can I do this with no rated shaft and no fire or radiation dampers?
CBC 707.2 (in the 2010 codes, it’s 708.2) exception #1 says “a shaft enclosure is not required for openings totally within an individual dwelling unit and connecting four stories or less.” Obviously, I’m less than 4 stories, and in the scenario I described above, it sounds like I am not “opening” the first floor-apartment duct into the second floor-apartment unit, even though I’m only separated from it by a nonrated furred wall? I guess I've confused myself as to whether the term "opening" refers to a penetration of a fire rated assembly, or to an actual atmospheric connection between the units. The latter means I could do this without shafts or dampers, right?
I want to run the 7” dia. range hood and bathroom exhaust fan ducts from the first floor across through (1) a horizontal nonrated gyp board soffit below the rated floor-ceiling assembly, then up (2) penetrating the 1 hour floor-ceiling assembly, then (3) through a nonrated furred gyp board wall in the back of a closet in the 2nd floor unit, then finally (4) through the 1-hour roof assembly. The ducts run individually, and do not open into the second floor unit.
Can I do this with no rated shaft and no fire or radiation dampers?
CBC 707.2 (in the 2010 codes, it’s 708.2) exception #1 says “a shaft enclosure is not required for openings totally within an individual dwelling unit and connecting four stories or less.” Obviously, I’m less than 4 stories, and in the scenario I described above, it sounds like I am not “opening” the first floor-apartment duct into the second floor-apartment unit, even though I’m only separated from it by a nonrated furred wall? I guess I've confused myself as to whether the term "opening" refers to a penetration of a fire rated assembly, or to an actual atmospheric connection between the units. The latter means I could do this without shafts or dampers, right?