20190071 Permit PkgROOF ASSEMBLIES
R905.2.8.2 Valleys. Valley linings shall be installed in
accordance with the manufacturer's instructions before
applying shingles. Valley linings of the following types
shall be permitted:
1. For open valleys (valley lining exposed) lined
with metal, the valley lining shall be not less than
24 inches (610 mm) wide and of any of the corro-
sion -resistant metals in Table R905.2.8.2.
2. For open valleys, valley lining of two plies of
mineral -surfaced roll roofing, complying with
ASTM D 3909 or ASTM D 6380 Class M, shall
be permitted. The bottom layer shall be 18 inches
(457 mm) and the top layer not less than 36
inches (914 mm) wide.
3. For closed valleys (valley covered with shingles),
valley lining of one ply of smooth roll roofing
complying with ASTM D 6380 and not less than
36 inches wide (914 mm) or valley lining as
described in Item 1 or 2 shall be permitted. Self -
adhering polymer modified bitumen underlay-
ment complying with ASTM D 1970 shall be per-
mitted in lieu of the lining material.
R905.2.8.3 Sidewall flashing. Base flashing against a
vertical sidewall shall be continuous or step flashing
and shall be not less than 4 inches (102 mm) in height
and 4 inches (102 mm) in width and shall direct water
away from the vertical sidewall onto the roof or into the
gutter. Where siding is provided on the vertical side-
wall, the vertical leg of the flashing shall be continuous
under the siding. Where anchored masonry veneer is
provided on the vertical sidewall, the base flashing
shall be provided in accordance with this section and
counterflashing shall be provided in accordance with
Section R703.7.2.2. Where exterior plaster or adhered
masonry veneer is provided on the vertical sidewall, the
base flashing shall be provided in accordance with this
section and Section R703.6.3.
R905.2.8.4 Other flashing. Flashing against a vertical
front wall, as well as soil stack, vent pipe and chimney
flashing, shall be applied in accordance with the asphalt
shingle manufacturer's printed instructions.
R905.2.8.5 Drip edge. A drip edge shall be provided at
eaves and rake edges of shingle roofs. Adjacent segments
of drip edge shall be overlapped not less than 2 inches (51
mm). Drip edges shall extend not less than 1/, inch (6.4
mm) below the roof sheathing and extend up back onto
the roof deck not less than 2 inches (51 mm). Drip edges
shall be mechanically fastened to the roof deck at not
more than 12 inches (305 mm) o.c. with fasteners as spec-
ified in Section R905.2.5. Underlayment shall be
installed over the drip edge along eaves and under the
underlayment along rake edges.
R905.3 Clay and concrete tile. The installation of clay and
concrete tile shall comply with the provisions of this section.
R905.3.1 Deck requirements. Concrete and clay tile shall
be installed only over solid sheathing or spaced structural
sheathing boards.
R905.3.2 Deck slope. Clay and concrete roof tile shall be
installed on roof slopes of two and one-half units vertical
in 12 units horizontal (21/2:12) or greater. For roof slopes
from two and one-half units vertical in 12 units horizontal
(21/2:12) to four units vertical in 12 units horizontal (4:12),
double underlayment application is required in accordance
with Section R905.3.3.
R905.3.3 Underlayment. Underlayment shall comply
with Section R905.1.1.
R905.3.4 Clay tile. Clay roof tile shall comply with
ASTM C 1167.
R905.3.5 Concrete tile. Concrete roof tile shall comply
with ASTM C 1492.
R905.3.6 Fasteners. Nails shall be corrosion resistant and
not less than 11 gage, 5/,6 -inch (11 mm) head, and of suffi-
cient length to penetrate the deck not less than 3/4 inch (19
mm) or through the thickness of the deck, whichever is
less. Attaching wire for clay or concrete tile shall not be
smaller than 0.083 inch (2 mm). Perimeter fastening areas
include three tile courses but not less than 36 inches (914
TABLE R905.2.8.2
VALLEY LINING MATERIAL
MATERIAL
MINIMUM THICKNESS
(inches)
GAGE
WEIGHT
(pounds)
Cold -rolled copper
0.0216 nominal
—
ASTM B 370, 16 oz. per square foot
Lead -coated copper
0.0216 nominal
—
ASTM B 101, 16 oz. per square foot
High -yield copper
0.0162 nominal
—
ASTM B 370, 12 oz. per square foot
Lead -coated high -yield copper
0.0162 nominal
—
ASTM B 101, 12 oz. per square foot
Aluminum
0.024
—
Stainless steel
—
28
—
Galvanized steel
0.0179
26 (zinc coated G90)
—
Zinc alloy
0.027
—
—
Lead
—
—
21/2
Painted terne
—
—
20
For SI: 1 inch = 25.4 mm, 1 pound = 0.454 kg.
418 2015 INTERNATIONAL RESIDENTIAL CODE®