(A) Two-family dwellings.
(1) Dwelling units in two-family dwellings shall be separated from each other by wall and floor assemblies having not less than a one-hour fire-resistance rating where tested in accordance with ASTM E119 or UL 263. Fire-resistance-rated floor/ceiling and wall assemblies shall extend to and be tight against the exterior wall, and wall assemblies shall extend from the foundation to the underside of the roof sheathing.
(2) Exceptions.
(a) A fire-resistance rating of one-half hour shall be permitted in buildings equipped throughout with an automatic sprinkler system installed in accordance with NFPA 13;
(b) Wall assemblies need not extend through attic spaces where the ceiling is protected by not less than five-eighths-inch Type X gypsum board, an attic draft stop constructed, as specified in the North Carolina Building Code, is provided above and along the wall assembly separating the dwellings, and the structural framing supporting the ceiling is protected by not less than one-half-inch gypsum board or equivalent.
(3) Supporting construction. Where floor assemblies are required to be fire-resistance rated by the North Carolina Building Code, the supporting construction of such assemblies shall have an equal or greater fire-resistance rating.
(4) Dwelling unit rated penetrations. Penetrations of wall or floor-ceiling assemblies required to be fire-resistance rated shall be rated and protected in accordance with the North Carolina Building Code.
(5) Through penetrations.
(a) Through penetrations of fire-resistance-rated wall or floor assemblies shall comply with the North Carolina Building Code.
(b) Exception. Where the penetrating items are steel, ferrous or copper pipes, tubes or conduits, the annular space shall be protected as follows.
1. In concrete or masonry wall or floor assemblies, concrete, grout or mortar shall be permitted where installed to the full thickness of the wall or floor assembly or the thickness required to maintain the fire-resistance rating, provided that both of the following are complied with:
a. The nominal diameter of the penetrating item is not more than six inches;
b. The area of the opening through the wall does not exceed 144 square inches;
2. The material used to fill the annular space shall prevent the passage of flame and hot gases sufficient to ignite cotton waste, where subjected to ASTM E119 or UL 263 time temperature fire conditions, under a positive pressure differential of not less than 0.01 inch of water (3 Pa) at the location of the penetration, for the time period equivalent to the fire-resistance rating of the construction penetrated.
(6) Fire-resistance-rated assembly. Penetrations shall be installed as tested in the approved fire-resistance-rated assembly.
(7) Penetration firestop system. Penetrations shall be protected by an approved penetration firestop system installed as tested in accordance with ASTM E814 or UL 1479, with a positive pressure differential of not less than one-hundredth inch of water (3 Pa), and shall have an F rating of not less than the required fire-resistance rating of the wall or floor-ceiling assembly penetrated.
(8) Membrane penetrations.
(a) Membrane penetrations shall comply with this section. Where walls are required to have a fire-resistance rating, recessed fixtures shall be installed so that the required fire-resistance rating will not be reduced.
(b) Exceptions.
1. Membrane penetrations of not more than two-hour fire-resistance-rated walls and partitions by steel electrical boxes that do not exceed 16 square inches in area, provided that the aggregate area of the openings through the membrane does not exceed 100 square inches in any 100 square feet of wall area. The annular space between the wall membrane and the box shall not exceed one-eighth inch. Such boxes on opposite sides of the wall shall be separated by one of the following:
a. By a horizontal distance of not less than 24 inches, where the wall or partition is constructed with individual non-communicating stud cavities;
b. By a horizontal distance of not less than the depth of the wall cavity, where the wall cavity is filled with cellulose loose-fill, rockwool or slag mineral wool insulation;
c. By solid fire blocking in accordance with the North Carolina Building Code;
d. By protecting both boxes with listed putty pads;
e. By other listed materials and methods.
2. Membrane penetrations by listed electrical boxes of any materials, provided that the boxes have been tested for use in fire-resistance-rated assemblies and are installed in accordance with the instructions included in the listing. The annular space between the wall membrane and the box shall not exceed one-eighth inch unless listed otherwise. Such boxes on opposite sides of the wall shall be separated by one of the following;
a. By the horizontal distance specified in the listing of the electrical boxes;
b. By solid fire blocking in accordance with the North Carolina Building Code;
c. By protecting both boxes with listed putty pads;
d. By other listed materials and methods.
3. The annular space created by the penetration of a fire sprinkler, provided that it is covered by a metal escutcheon plate.
(B) Dwelling-garage opening and penetration protection. Openings and penetrations through the walls or ceilings separating the dwelling from the garage shall be in accordance with the following.
(1) Opening protection.
(a) Openings from a private garage directly into a room used for sleeping purposes shall not be permitted.
(b) Other openings between the garage and residence shall be equipped with solid wood doors not less than one and three-eighths inches in thickness, solid or honeycomb-core steel doors not less than one and three-eighths inches-thick, or 20-minute fire-rated doors.
(c) Exception. A disappearing/pull-down stairway to uninhabited attic space, with minimum three-eighths-inch (nominal), fire-retardant-treated structural panel, is equivalent to the separation requirement from attics in the North Carolina Building Code.
(2) Duct penetration. Ducts in the garage and ducts penetrating the walls or ceilings separating the dwelling from the garage shall be constructed of a minimum no. 26-gauge sheet steel or other approved material, and shall not have openings into the garage.
(C) Dwelling-garage fire separation. The garage shall be separated as required in the following table. Openings in garage walls shall comply the North Carolina Building Code. The wall separation provisions of the table shall not apply to garage walls that are perpendicular to the adjacent dwelling unit wall.
DWELLING-GARAGE SEPARATION
| |
Separation | Material |
From the residence and attics | Not less than ½-inch gypsum board or equivalent applied to the garage side |
From habitable rooms above the garage (footnote a) | Not less than -inch Type X gypsum board or equivalent |
Structure(s) supporting floor/ceiling assemblies used for separation required by this section | Not less than ½-inch gypsum board or equivalent |
Garages located less than 3 feet from a dwelling unit on the same lot | Not less than ½-inch gypsum board or equivalent applied to the interior side of exterior walls that are within this area |
Footnote a: For dwelling units constructed prior to the 2012 edition of the North Carolina Residential Code, ½-inch or greater existing gypsum board on the bottom side of the garage ceiling shall be acceptable. Joints shall be taped. | |
(D) Under-stair protection. Enclosed accessible space under stairs shall have walls, under-stair surface and any soffits protected on the enclosed side with one-half-inch gypsum board.
(Ord. 2019-08-01, passed 9-9-19)