R302.2.2 12-09-2019R302.2 Townhouses. Common walls separating townhouses shall be assigned a fire-resistance rating in accordance with Section R302.2, Item 1 or 2. The common wall shared by two townhouses
shall be constructed without plumbing or mechanical equipment, ducts or vents in the cavity of the common wall. The wall shall be rated for fire exposure from both sides and shall extend
to and be tight against exterior walls and the underside of the roof sheathing. Electrical installations shall be in accordance with Chapters 34 through 43. Penetrations of the membrane
of common walls for electrical outlet boxes shall be in accordance with Section R302.4.
1. Where a fire sprinkler system in accordance with NFPA 13, 13R, or 13D is provided, the common wall shall be not less than a one-hour fire-resistance-rated wall assembly tested in
accordance with ASTM E 119 or UL 263.
2. Where a fire sprinkler system in accordance with NFPA 13, 13R, or 13D is not provided, the common wall shall be not less than a two-hour fire-resistance-rated fire wall assembly tested
in accordance with ASTM E119 or UL 263.
1. Where a fire sprinkler system in accordance with Section P2904 is provided, the common wall shall be not less than a 1-hour fire-resistance-rated wall assembly tested in accordance
with ASTM E119 or UL 263.
2. Where a fire sprinkler system in accordance with Section P2904 is not provided, the common wall shall be not less than a 2-hour fire-resistance-rated wall assembly tested in accordance
with ASTM E119 or UL 263.
R302.2.2
Exception: A parapet is not required in the preceding two cases where the roof covering complies with a
minimum Class C rating as tested in accordance with ASTM E108 or UL 790 and the roof decking or sheathing is of noncombustible materials or approved fire-retardant-treated wood for a
distance of 4 feet (1219 mm) on each side of the wall or walls, or one layer of 5/8-inch (15.9 mm) Type X gypsum board is installed directly beneath the roof decking or sheathing, supported
by not less than nominal 2-inch (51 mm) ledgers attached to the sides of the roof framing members, for a distance of not less than 4 feet (1219 mm) on each side of the wall or walls
and any openings or penetrations in the roof are not within 4 feet (1219 mm) of the common walls.