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ROOF ASSEMBLIES
TABLE R905.7.5(1) R905.8.1.1 Solid sheathing required. In areas where
WOOD SHINGLE WEATHER EXPOSURE AND ROOF SLOPE
the average daily temperature in January is 25°F (-4°C)
EXPOSURE (inches) or less, solid sheathing is required on that portion of the
ROOFING LENGTH
MATERIAL (inches) GRADE 3:12 pitch to 4:12 pitch or roof requiring an ice barrier.
< 4:12 steeper
3
No. 1 3 / 4 5 R905.8.2 Deck slope. Wood shakes shall only be used on
slopes of three units vertical in 12 units horizontal (25-per-
16 No. 2 3 / 2 4 cent slope) or greater.
1
No. 3 3 3 / 2 R905.8.3 Underlayment. Underlayment shall comply
1
1
1
Shingles of No. 1 4 / 4 5 / 2 with Section R905.1.1.
naturally 18 No. 2 4 4 /
1
durable 2 R905.8.3.1 Ice barrier. Where required, ice barriers
1
wood No. 3 3 / 2 4 shall comply with Section R905.1.2.
1
3
No. 1 5 / 4 7 / 2 R905.8.4 Interlayment. Interlayment shall comply with
1
24 No. 2 5 / 2 6 / 2 ASTM D226, Type I.
1
1
No. 3 5 5 / 2 R905.8.5 Material standards. Wood shakes shall comply
For SI: 1 inch = 25.4 mm. with the requirements of Table R905.8.5.
TABLE R905.7.5(2) TABLE R905.8.5
NAIL REQUIREMENTS FOR WOOD SHAKES AND WOOD SHINGLES WOOD SHAKE MATERIAL REQUIREMENTS
NAIL TYPE MINIMUM MINIMUM APPLICABLE
MINIMUM
SHAKES AND MINIMUM HEAD SIZE SHANK MATERIAL GRADES GRADING RULES
LENGTH DIAMETER
Wood shakes of naturally durable Cedar Shake and
3
18 straight-split 5d box 1 / 0.19 .080 wood 1 Shingle Bureau
4
18 and 24 handsplit 6d box 2 0.19 .0915 Tapersawn shakes of naturally Cedar Shake and
and resawn 1 or 2
durable wood Shingle Bureau
3
24 taper-split 5d box 1 / 0.19 .080 Preservative-treated shakes and Cedar Shake and
4
18 and 24 tapersawn 6d box 2 0.19 .0915 shingles of naturally durable wood 1 Shingle Bureau
Nail Type Minimum Fire-retardant-treated shakes and Cedar Shake and
Minimum
Shingles and Minimum Head Size Shank 1
Length Diameter shingles of naturally durable wood Shingle Bureau
1
16 and 18 3d box 1 / 0.19 .080 Preservative-treated tapersawn Forest Products
4
1
24 4d box 1 / 0.19 .080 shakes of Southern pine treated in 1 or 2 Laboratory of the
accordance with AWPA Standard
2
U1 (Commodity Specification A, Texas Forest
For SI: 1 inch = 25.4 mm. Special Requirement 4.6) Services
R905.7.6 Valley flashing. Roof flashing shall be not less
than No. 26 gage [0.019 inches (0.5 mm)] corrosion-resis- R905.8.6 Application. Wood shakes shall be installed in
tant sheet metal and shall extend 10 inches (254 mm) from accordance with this chapter and the manufacturer’s
the centerline each way for roofs having slopes less than installation instructions. Wood shakes shall be laid with a
12 units vertical in 12 units horizontal (100-percent slope), side lap not less than 1 / inches (38 mm) between joints in
1
2
and 7 inches (178 mm) from the centerline each way for adjacent courses. Spacing between shakes in the same
slopes of 12 units vertical in 12 units horizontal (100-per- course shall be / inch to / inch (9.5 mm to 15.9 mm)
3
5
8
8
cent slope) and greater. Sections of flashing shall have an including tapersawn shakes. Weather exposures for wood
end lap of not less than 4 inches (102 mm). shakes shall not exceed those set in Table R905.8.6. Fas-
R905.7.7 Label required. Each bundle of shingles shall teners for untreated (naturally durable) wood shakes shall
be identified by a label of an approved grading or inspec- be box nails in accordance with Table R905.7.5(2). Nails
tion bureau or agency. shall be stainless steel Type 304, or Type 316 or hot-
dipped with a coating weight of ASTM A153 Class D (1.0
R905.8 Wood shakes. The installation of wood shakes shall oz/ft ). Alternatively, two 16-gage Type 304 or Type 316
2
comply with the provisions of this section. 7
stainless steel staples, with crown widths / inch (11.1
16
3
R905.8.1 Deck requirements. Wood shakes shall be used mm) minimum, / inch (19.1 mm) maximum, shall be
4
only on solid or spaced sheathing. Where spaced sheathing used. Fasteners installed within 15 miles (24 km) of salt-
is used, sheathing boards shall be not less than 1-inch by water coastal areas shall be stainless steel Type 316. Wood
4-inch (25 mm by 102 mm) nominal dimensions and shall shakes shall be attached to the roof with two fasteners per
be spaced on centers equal to the weather exposure to shake positioned in accordance with the manufacturer’s
coincide with the placement of fasteners. Where 1-inch by installation instructions Fasteners for fire-retardant-treated
4-inch (25 mm by 102 mm) spaced sheathing is installed (as defined in Section R902) shakes or pressure-impreg-
at 10 inches (254 mm) on center, additional 1-inch by 4- nated-preservative-treated shakes of naturally durable
inch (25 mm by 102 mm) boards shall be installed wood in accordance with AWPA U1 shall be stainless
between the sheathing boards. steel Type 316. Fasteners shall have a minimum penetra-
440 2018 INTERNATIONAL RESIDENTIAL CODE ®
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