When is a T-Rating required for penetrations?
The CBC requires through penetrations of fire-resistance rated floors, floor/ceiling assemblies or the ceiling membrane of a roof/ceiling assembly to be protected by a through-penetration firestop system having a F-rating and a T-rating of not less than 1 hour, but not less than the required rating of the floor penetrated. Floor penetrations contained and located within the cavity of a wall (above the floor or below the floor) do not require a T-rating.
The 2013 and 2016 CBC permit floor penetrations by floor drains, tub drains or shower drains contained and located within the concealed space of a horizontal assembly without a T rating. Acceptance of such configurations shall be on a case by case basis for projects constructed in accordance with the 2007 CBC or 2010 CBC.
The 2016 CBC does not require a T rating for floor penetrations of maximum 4-inch nominal diameter penetrating directly into metal-enclosed electrical power switchgear. Acceptance of such configurations shall be on a case by case basis for projects constructed in accordance with the 2007 CBC, 2010 CBC or 2013 CBC.
There are few limited exceptions to this requirement in the CBC. These include penetrating items with a maximum 6-inch nominal diameter penetrating a single fire-resistance-rated floor assembly, provided the aggregate area of the openings through the assembly does not exceed 144 square inches in any 100 square feet of floor area. Refer to the CBC for additional exceptions.
2007 California Building Code (CBC) Sections 712.4.1.1 and 712.4.1.1.2
2010 California Building Code (CBC) Sections 713.4.1.1 and 713.4.1.1.2
2013 California Building Code (CBC) Sections 714.4.1.1 and 714.4.1.1.2
2016 California Building Code (CBC) Sections 714.4.1.1 and 714.4.1.2