Page 84 - 2018_IRC

BUILDING PLANNING

Electrical installations shall be in accordance with Chap- fire-resistance rating. The wall shall be rated for
ters 34 through 43. Penetrations of the membrane of com- exposure from both sides.
mon walls for electrical outlet boxes shall be in R302.2.5 Parapet construction. Parapets shall have the
accordance with Section R302.4.
same fire-resistance rating as that required for the support-
1. Where a fire sprinkler system in accordance with ing wall or walls. On any side adjacent to a roof surface, the
Section P2904 is provided, the common wall shall parapet shall have noncombustible faces for the uppermost
be not less than a 1-hour fire-resistance-rated wall 18 inches (457 mm), to include counterflashing and coping
assembly tested in accordance with ASTM E119, materials. Where the roof slopes toward a parapet at slopes
UL 263 or Section 703.3 of the International Build- greater than 2 units vertical in 12 units horizontal (16.7-per-
ing Code. cent slope), the parapet shall extend to the same height as
any portion of the roof within a distance of 3 feet (914 mm),
2. Where a fire sprinkler system in accordance with
Section P2904 is not provided, the common wall and the height shall be not less than 30 inches (762 mm).
shall be not less than a 2-hour fire-resistance-rated R302.2.6 Structural independence. Each individual
wall assembly tested in accordance with ASTM townhouse shall be structurally independent.
E119, UL 263 or Section 703.3 of the International Exceptions:
Building Code.
1. Foundations supporting exterior walls or com-
R302.2.3 Continuity. The fire-resistance-rated wall or
assembly separating townhouses shall be continuous from mon walls.
the foundation to the underside of the roof sheathing, deck 2. Structural roof and wall sheathing from each unit
or slab. The fire-resistance rating shall extend the full length fastened to the common wall framing.
of the wall or assembly, including wall extensions through 3. Nonstructural wall and roof coverings.
and separating attached enclosed accessory structures.
4. Flashing at termination of roof covering over
R302.2.4 Parapets for townhouses. Parapets constructed
in accordance with Section R302.2.5 shall be constructed common wall.
for townhouses as an extension of exterior walls or com- 5. Townhouses separated by a common wall as pro-
mon walls in accordance with the following: vided in Section R302.2.2, Item 1 or 2.
1. Where roof surfaces adjacent to the wall or walls are R302.3 Two-family dwellings. Dwelling units in two-family
at the same elevation, the parapet shall extend not less dwellings shall be separated from each other by wall and
than 30 inches (762 mm) above the roof surfaces. floor assemblies having not less than a 1-hour fire-resistance
rating where tested in accordance with ASTM E119, UL 263
2. Where roof surfaces adjacent to the wall or walls are or Section 703.3 of the International Building Code. Fire-
at different elevations and the higher roof is not resistance-rated floor/ceiling and wall assemblies shall
more than 30 inches (762 mm) above the lower roof, extend to and be tight against the exterior wall, and wall
the parapet shall extend not less than 30 inches (762 assemblies shall extend from the foundation to the underside
mm) above the lower roof surface.
of the roof sheathing.
Exception: A parapet is not required in the preced- Exceptions:
ing two cases where the roof covering complies
with a minimum Class C rating as tested in accor- 1. A fire-resistance rating of / hour shall be permitted in
1
2
dance with ASTM E108 or UL 790 and the roof buildings equipped throughout with an automatic
decking or sheathing is of noncombustible materi- sprinkler system installed in accordance with NFPA
als or fire-retardant-treated wood for a distance of 4 13.
feet (1219 mm) on each side of the wall or walls, or 2. Wall assemblies need not extend through attic spaces
5
one layer of / -inch (15.9 mm) Type X gypsum where the ceiling is protected by not less than / -inch
5
8
8
board is installed directly beneath the roof decking (15.9 mm) Type X gypsum board, an attic draft stop
or sheathing, supported by not less than nominal 2- constructed as specified in Section R302.12.1 is pro-
inch (51 mm) ledgers attached to the sides of the vided above and along the wall assembly separating
roof framing members, for a distance of not less the dwellings and the structural framing supporting
than 4 feet (1219 mm) on each side of the wall or the ceiling is protected by not less than / -inch (12.7
1
walls and any openings or penetrations in the roof mm) gypsum board or equivalent. 2
are not within 4 feet (1219 mm) of the common
walls. Fire-retardant-treated wood shall meet the R302.3.1 Supporting construction. Where floor assem-
requirements of Sections R802.1.5 and R803.2.1.2. blies are required to be fire-resistance rated by Section
R302.3, the supporting construction of such assemblies
3. A parapet is not required where roof surfaces adja- shall have an equal or greater fire-resistance rating.
cent to the wall or walls are at different elevations
and the higher roof is more than 30 inches (762 mm) R302.4 Dwelling unit rated penetrations. Penetrations of
above the lower roof. The common wall construc- wall or floor-ceiling assemblies required to be fire-resistance
tion from the lower roof to the underside of the rated in accordance with Section R302.2 or R302.3 shall be
higher roof deck shall have not less than a 1-hour protected in accordance with this section.

2018 INTERNATIONAL RESIDENTIAL CODE ® 59
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