International Building Code Section 1507


International Building Code 1507.10

Built-up roofs. The installation of built-up roofs shall
comply with the provisions of this section.

Slope. Built-up roofs shall have a design slope of
a minimum of one-fourth unit vertical in 12 units horizontal
(2-percent slope) for drainage, except for coal-tar built-up
roofs that shall have a design slope of a minimum
one-eighth unit vertical in 12 units horizontal (1-percent
slope).

Material standards. Built-up roof covering
materials shall comply with the standards in Table
1507.10.2.

International Building Code 1507.1

Scope. Roof coverings shall be applied in accordance
with the applicable provisions of this section and the manufacturer’s
installation instructions.

International Building Code 1507.10.1

Slope. Built-up roofs shall have a design slope of
a minimum of one-fourth unit vertical in 12 units horizontal
(2-percent slope) for drainage, except for coal-tar built-up
roofs that shall have a design slope of a minimum
one-eighth unit vertical in 12 units horizontal (1-percent
slope).

International Building Code 1507.10.2

Material standards. Built-up roof covering
materials shall comply with the standards in Table
1507.10.2.

International Building Code 1507.11

Modified bitumen roofing. The installation of modified
bitumen roofing shall comply with the provisions of this
section.
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ROOF ASSEMBLIES AND ROOFTOP STRUCTURES

Slope. Modified bitumen membrane roofs shall
have a design slope of a minimum of one-fourth unit vertical
in 12 units horizontal (2-percent slope) for drainage.

Material standards. Modified bitumen roof
coverings shall comply with CGSB 37-GP-56M, ASTM D
6162, ASTM D 6163, ASTM D 6164, ASTM D 6222,
ASTM D 6223 or ASTM D 6298.

International Building Code 1507.11.1

Slope. Modified bitumen membrane roofs shall
have a design slope of a minimum of one-fourth unit vertical
in 12 units horizontal (2-percent slope) for drainage.

International Building Code 1507.11.2

Material standards. Modified bitumen roof
coverings shall comply with CGSB 37-GP-56M, ASTM D
6162, ASTM D 6163, ASTM D 6164, ASTM D 6222,
ASTM D 6223 or ASTM D 6298.

International Building Code 1507.12

Thermoset single-ply roofing. The installation of
thermoset single-ply roofing shall comply with the provisions
of this section.

Slope. Thermoset single-ply membrane roofs
shall have a design slope of a minimum of one-fourth unit
vertical in 12 units horizontal (2-percent slope) for drainage.

Material standards. Thermoset single-ply roof
coverings shall comply with ASTMD4637, ASTMD5019
or CGSB 37-GP-52M.

International Building Code 1507.12.1

Slope. Thermoset single-ply membrane roofs
shall have a design slope of a minimum of one-fourth unit
vertical in 12 units horizontal (2-percent slope) for drainage.

International Building Code 1507.12.2

Material standards. Thermoset single-ply roof
coverings shall comply with ASTMD4637, ASTMD5019
or CGSB 37-GP-52M.

International Building Code 1507.13

Thermoplastic single-ply roofing. The installation
of thermoplastic single-ply roofing shall comply with the provisions
of this section.

Slope. Thermoplastic single-ply membrane
roofs shall have a design slope of a minimum of one-fourth
unit vertical in 12 units horizontal (2-percent slope).

Material standards. Thermoplastic single-ply
roof coverings shall comply with ASTM D 4434, ASTM D
6754, ASTM D 6878 or CGSB CAN/CGSB 37-54.

International Building Code 1507.13.1

Slope. Thermoplastic single-ply membrane
roofs shall have a design slope of a minimum of one-fourth
unit vertical in 12 units horizontal (2-percent slope).

International Building Code 1507.13.2

Material standards. Thermoplastic single-ply
roof coverings shall comply with ASTM D 4434, ASTM D
6754, ASTM D 6878 or CGSB CAN/CGSB 37-54.

International Building Code 1507.14

Sprayed polyurethane foam roofing. The installation
of sprayed polyurethane foam roofing shall comply with
the provisions of this section.

Slope. Sprayed polyurethane foam roofs shall
have a design slope of a minimum of one-fourth unit vertical
in 12 units horizontal (2-percent slope) for drainage.

Material standards. Spray-applied polyurethane
foam insulation shall comply with ASTM C 1029.

Application. Foamed-in-place roof insulation
shall be installed in accordance with the manufacturer’s
instructions. A liquid-applied protective coating that complies
with Section 1507.15 shall be applied no less than 2
hours nor more than 72 hours following the application of
the foam.

Foam plastics. Foam plastic materials and installation
shall comply with Chapter 26.

International Building Code 1507.14.1

Slope. Sprayed polyurethane foam roofs shall
have a design slope of a minimum of one-fourth unit vertical
in 12 units horizontal (2-percent slope) for drainage.

International Building Code 1507.14.2

Material standards. Spray-applied polyurethane
foam insulation shall comply with ASTM C 1029.

International Building Code 1507.14.3

Application. Foamed-in-place roof insulation
shall be installed in accordance with the manufacturer’s
instructions. A liquid-applied protective coating that complies
with Section 1507.15 shall be applied no less than 2
hours nor more than 72 hours following the application of
the foam.

International Building Code 1507.14.4

Foam plastics. Foam plastic materials and installation
shall comply with Chapter 26.

International Building Code 1507.15

Liquid-applied coatings. The installation of liquid-
applied coatings shall comply with the provisions of this
section.

Slope. Liquid-applied roofs shall have a design
slope of a minimum of one-fourth unit vertical in 12 units
horizontal (2-percent slope).

Material standards. Liquid-applied roof coatings
shall comply with ASTM C 836, ASTM C 957, ASTM
D1227 orASTMD3468,ASTMD6083 orASTMD6694.

International Building Code 1507.15.1

Slope. Liquid-applied roofs shall have a design
slope of a minimum of one-fourth unit vertical in 12 units
horizontal (2-percent slope).

International Building Code 1507.15.2

Material standards. Liquid-applied roof coatings
shall comply with ASTM C 836, ASTM C 957, ASTM
D1227 orASTMD3468,ASTMD6083 orASTMD6694.

International Building Code 1507.2

Asphalt shingles. The installation of asphalt shingles
shall comply with the provisions of this section.

Deck requirements. Asphalt shingles shall be fastened
to solidly sheathed decks.

Slope. Asphalt shingles shall only be used on roof
slopes of two units vertical in 12 units horizontal (17-percent
slope) or greater. For roof slopes from two units vertical
in 12 units horizontal (17-percent slope) up to four units vertical
in 12 units horizontal (33-percent slope), double
underlayment application is required in accordance with
Section 1507.2.8.

Underlayment. Unless otherwise noted, required
underlayment shall conform to ASTM D 226, Type I,
ASTM D 4869, Type I, or ASTM D 6757.

Self-adhering polymer modified bitumen sheet.
Self-adhering polymer modified bitumen sheet shall comply
with ASTM D 1970.

Asphalt shingles. Asphalt shingles shall have
self-seal strips or be interlocking and comply withASTMD
225 or ASTMD3462. Asphalt shingle packaging shall bear
labeling indicating compliance withASTMD3161 or a listing
by an approved testing agency in accordance with the
requirements of Section 1609.5.2.

Fasteners. Fasteners for asphalt shingles shall be
galvanized, stainless steel, aluminum or copper roofing
nails, minimum 12 gage [0.105 inch (2.67 mm)] shank with
a minimum 0.375 inch-diameter (9.5 mm) head, of a length
to penetrate through the roofing materials and a minimum of
0.75 inch (19.1 mm) into the roof sheathing. Where the roof
sheathing is less than 0.75 inch (19.1 mm) thick, the nails
shall penetrate through the sheathing. Fasteners shall comply
with ASTM F 1667.

Attachment. Asphalt shingles shall have the minimum
number of fasteners required by the manufacturer and
Section 1504.1. Asphalt shingles shall be secured to the roof
with not less than four fasteners per strip shingle or two fasteners
per individual shingle. Where the roof slope exceeds
20 units vertical in 12 units horizontal (166-percent slope),
asphalt shingles shall be installed in accordance with the
manufacturer’s printed installation instructions for
steep-slope roof applications.

Underlayment application. For roof slopes from
two units vertical in 12 units horizontal (17-percent slope)
and up to four units vertical in 12 units horizontal (33-percent
slope), underlayment shall be two layers applied in the
following manner. Apply a minimum 19-inch-wide (483
mm) strip of underlayment felt parallel with and starting at
the eaves, fastened sufficiently to hold in place. Starting at
the eave, apply 36-inch-wide (914 mm) sheets of
underlayment overlapping successive sheets 19 inches (483
mm), by fastened sufficiently to hold in place. Distortions in
the underlayment shall not interfere with the ability of the
shingles to seal. For roof slopes of four units vertical in 12
units horizontal (33-percent slope) or greater, underlayment
shall be one layer applied in the following manner.
Underlayment shall be applied shingle fashion, parallel to
and starting from the eave and lapped 2 inches (51 mm), fastened
sufficiently to hold in place. Distortions in the
underlayment shall not interfere with the ability of the shingles
to seal.

High wind attachment. Underlayment
applied in areas subject to high winds (greater than 110
mph in accordance with Figure 1609) shall be applied
with corrosion- resistant fasteners in accordance with the
manufacturer’s instructions. Fasteners are to be applied
along the overlap at a maximum spacing of 36 inches
(914 mm) on center.

Icedammembrane. In areas where there has
been a history of ice forming along the eaves causing a
backup of water, a membrane that consists of at least two
layers of underlayment cemented together or of a
self-adhering polymer modified bitumen sheet shall be
used in lieu of normal underlayment and extend from the
eave’s edge to a point at least 24 inches (610 mm) inside
the exterior wall line of the building.
Exception: Detached accessory structures that contain
no conditioned floor area.

Flashings. Flashing for asphalt shingles shall
comply with this section. Flashing shall be applied in accordance
with this section and the asphalt shingle manufacturer’s
printed instructions.

Base and cap flashing. Base and cap flashing
shall be installed in accordance with the manufacturer’s
instructions. Base flashing shall be of either
corrosion-resistant metal of minimum nominal
0.019-inch (0.483 mm) thickness or mineral-surfaced
roll roofing weighing a minimum of 77 pounds per 100
square feet (3.76 kg/m2). Cap flashing shall be corrosion-
resistant metal of minimum nominal 0.019-inch
(0.483 mm) thickness.

Valleys. Valley linings shall be installed in
accordance with the manufacturer’s instructions before
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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 at least 16 inches
(406 mm) wide and of any of the corrosion-resistant
metals in Table 1507.2.9.2.
2. For open valleys, valley lining of two plies of mineral-
surfaced roll roofing complying with ASTM
D 3909 or ASTM D 6380 shall be permitted. The
bottom layer shall be 18 inches (457 mm) and the
top layer a minimum of 36 inches (914 mm)wide.
3. For closed valleys (valleys covered with shingles),
valley lining of one ply of smooth roll roofing
complying with ASTM D 6380, Class S Type III,
Class M Type II or ASTM D 3909 and at least 36
inches (914 mm) wide or types as described in
Items 1 and 2 above shall be permitted. Specialty
underlayment shall comply with ASTM D 1970.

Drip edge. Provide drip edge at eaves and
gables of shingle roofs. Overlap to be a minimum of 2
inches (51 mm). Eave drip edges shall extend 0.25 inch
(6.4 mm) below sheathing and extend back on the roof a
minimum of 2 inches (51 mm). Drip edge shall be
mechanically fastened a maximum of 12 inches (305
mm) o.c.

Crickets and saddles. A cricket or saddle
shall be installed on the ridge side of any chimney or penetration
greater than 30 inches (762 mm) wide as measured
perpendicular to the slope. Cricket or saddle
coverings shall be sheet metal or of the same material as
the roof covering.

International Building Code 1507.2.1

Deck requirements. Asphalt shingles shall be fastened
to solidly sheathed decks.

International Building Code 1507.2.2

Slope. Asphalt shingles shall only be used on roof
slopes of two units vertical in 12 units horizontal (17-percent
slope) or greater. For roof slopes from two units vertical
in 12 units horizontal (17-percent slope) up to four units vertical
in 12 units horizontal (33-percent slope), double
underlayment application is required in accordance with
Section 1507.2.8.

International Building Code 1507.2.3

Underlayment. Unless otherwise noted, required
underlayment shall conform to ASTM D 226, Type I,
ASTM D 4869, Type I, or ASTM D 6757.

International Building Code 1507.2.4

Self-adhering polymer modified bitumen sheet.
Self-adhering polymer modified bitumen sheet shall comply
with ASTM D 1970.

International Building Code 1507.2.5

Asphalt shingles. Asphalt shingles shall have
self-seal strips or be interlocking and comply withASTMD
225 or ASTMD3462. Asphalt shingle packaging shall bear
labeling indicating compliance withASTMD3161 or a listing
by an approved testing agency in accordance with the
requirements of Section 1609.5.2.

International Building Code 1507.2.6

Fasteners. Fasteners for asphalt shingles shall be
galvanized, stainless steel, aluminum or copper roofing
nails, minimum 12 gage [0.105 inch (2.67 mm)] shank with
a minimum 0.375 inch-diameter (9.5 mm) head, of a length
to penetrate through the roofing materials and a minimum of
0.75 inch (19.1 mm) into the roof sheathing. Where the roof
sheathing is less than 0.75 inch (19.1 mm) thick, the nails
shall penetrate through the sheathing. Fasteners shall comply
with ASTM F 1667.

International Building Code 1507.2.7

Attachment. Asphalt shingles shall have the minimum
number of fasteners required by the manufacturer and
Section 1504.1. Asphalt shingles shall be secured to the roof
with not less than four fasteners per strip shingle or two fasteners
per individual shingle. Where the roof slope exceeds
20 units vertical in 12 units horizontal (166-percent slope),
asphalt shingles shall be installed in accordance with the
manufacturer’s printed installation instructions for
steep-slope roof applications.

International Building Code 1507.2.8

Underlayment application. For roof slopes from
two units vertical in 12 units horizontal (17-percent slope)
and up to four units vertical in 12 units horizontal (33-percent
slope), underlayment shall be two layers applied in the
following manner. Apply a minimum 19-inch-wide (483
mm) strip of underlayment felt parallel with and starting at
the eaves, fastened sufficiently to hold in place. Starting at
the eave, apply 36-inch-wide (914 mm) sheets of
underlayment overlapping successive sheets 19 inches (483
mm), by fastened sufficiently to hold in place. Distortions in
the underlayment shall not interfere with the ability of the
shingles to seal. For roof slopes of four units vertical in 12
units horizontal (33-percent slope) or greater, underlayment
shall be one layer applied in the following manner.
Underlayment shall be applied shingle fashion, parallel to
and starting from the eave and lapped 2 inches (51 mm), fastened
sufficiently to hold in place. Distortions in the
underlayment shall not interfere with the ability of the shingles
to seal.

High wind attachment. Underlayment
applied in areas subject to high winds (greater than 110
mph in accordance with Figure 1609) shall be applied
with corrosion- resistant fasteners in accordance with the
manufacturer’s instructions. Fasteners are to be applied
along the overlap at a maximum spacing of 36 inches
(914 mm) on center.

Icedammembrane. In areas where there has
been a history of ice forming along the eaves causing a
backup of water, a membrane that consists of at least two
layers of underlayment cemented together or of a
self-adhering polymer modified bitumen sheet shall be
used in lieu of normal underlayment and extend from the
eave’s edge to a point at least 24 inches (610 mm) inside
the exterior wall line of the building.
Exception: Detached accessory structures that contain
no conditioned floor area.

International Building Code 1507.2.8.1

High wind attachment. Underlayment
applied in areas subject to high winds (greater than 110
mph in accordance with Figure 1609) shall be applied
with corrosion- resistant fasteners in accordance with the
manufacturer’s instructions. Fasteners are to be applied
along the overlap at a maximum spacing of 36 inches
(914 mm) on center.

International Building Code 1507.2.8.2

Icedammembrane. In areas where there has
been a history of ice forming along the eaves causing a
backup of water, a membrane that consists of at least two
layers of underlayment cemented together or of a
self-adhering polymer modified bitumen sheet shall be
used in lieu of normal underlayment and extend from the
eave’s edge to a point at least 24 inches (610 mm) inside
the exterior wall line of the building.
Exception: Detached accessory structures that contain
no conditioned floor area.

International Building Code 1507.2.9

Flashings. Flashing for asphalt shingles shall
comply with this section. Flashing shall be applied in accordance
with this section and the asphalt shingle manufacturer’s
printed instructions.

Base and cap flashing. Base and cap flashing
shall be installed in accordance with the manufacturer’s
instructions. Base flashing shall be of either
corrosion-resistant metal of minimum nominal
0.019-inch (0.483 mm) thickness or mineral-surfaced
roll roofing weighing a minimum of 77 pounds per 100
square feet (3.76 kg/m2). Cap flashing shall be corrosion-
resistant metal of minimum nominal 0.019-inch
(0.483 mm) thickness.

Valleys. Valley linings shall be installed in
accordance with the manufacturer’s instructions before
266 2006 INTERNATIONAL BUILDING CODE
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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 at least 16 inches
(406 mm) wide and of any of the corrosion-resistant
metals in Table 1507.2.9.2.
2. For open valleys, valley lining of two plies of mineral-
surfaced roll roofing complying with ASTM
D 3909 or ASTM D 6380 shall be permitted. The
bottom layer shall be 18 inches (457 mm) and the
top layer a minimum of 36 inches (914 mm)wide.
3. For closed valleys (valleys covered with shingles),
valley lining of one ply of smooth roll roofing
complying with ASTM D 6380, Class S Type III,
Class M Type II or ASTM D 3909 and at least 36
inches (914 mm) wide or types as described in
Items 1 and 2 above shall be permitted. Specialty
underlayment shall comply with ASTM D 1970.

Drip edge. Provide drip edge at eaves and
gables of shingle roofs. Overlap to be a minimum of 2
inches (51 mm). Eave drip edges shall extend 0.25 inch
(6.4 mm) below sheathing and extend back on the roof a
minimum of 2 inches (51 mm). Drip edge shall be
mechanically fastened a maximum of 12 inches (305
mm) o.c.

Crickets and saddles. A cricket or saddle
shall be installed on the ridge side of any chimney or penetration
greater than 30 inches (762 mm) wide as measured
perpendicular to the slope. Cricket or saddle
coverings shall be sheet metal or of the same material as
the roof covering.

International Building Code 1507.2.9.1

Base and cap flashing. Base and cap flashing
shall be installed in accordance with the manufacturer’s
instructions. Base flashing shall be of either
corrosion-resistant metal of minimum nominal
0.019-inch (0.483 mm) thickness or mineral-surfaced
roll roofing weighing a minimum of 77 pounds per 100
square feet (3.76 kg/m2). Cap flashing shall be corrosion-
resistant metal of minimum nominal 0.019-inch
(0.483 mm) thickness.

International Building Code 1507.2.9.2

Valleys. Valley linings shall be installed in
accordance with the manufacturer’s instructions before
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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 at least 16 inches
(406 mm) wide and of any of the corrosion-resistant
metals in Table 1507.2.9.2.
2. For open valleys, valley lining of two plies of mineral-
surfaced roll roofing complying with ASTM
D 3909 or ASTM D 6380 shall be permitted. The
bottom layer shall be 18 inches (457 mm) and the
top layer a minimum of 36 inches (914 mm)wide.
3. For closed valleys (valleys covered with shingles),
valley lining of one ply of smooth roll roofing
complying with ASTM D 6380, Class S Type III,
Class M Type II or ASTM D 3909 and at least 36
inches (914 mm) wide or types as described in
Items 1 and 2 above shall be permitted. Specialty
underlayment shall comply with ASTM D 1970.

International Building Code 1507.2.9.3

Drip edge. Provide drip edge at eaves and
gables of shingle roofs. Overlap to be a minimum of 2
inches (51 mm). Eave drip edges shall extend 0.25 inch
(6.4 mm) below sheathing and extend back on the roof a
minimum of 2 inches (51 mm). Drip edge shall be
mechanically fastened a maximum of 12 inches (305
mm) o.c.

International Building Code 1507.2.9.4

Crickets and saddles. A cricket or saddle
shall be installed on the ridge side of any chimney or penetration
greater than 30 inches (762 mm) wide as measured
perpendicular to the slope. Cricket or saddle
coverings shall be sheet metal or of the same material as
the roof covering.

International Building Code 1507.3

Clay and concrete tile. The installation of clay and
concrete tile shall comply with the provisions of this section.

Deck requirements. Concrete and clay tile shall
be installed only over solid sheathing or spaced structural
sheathing boards.

Deck slope. Clay and concrete roof tile shall be
installed on roof slopes of 21/2 units vertical in 12 units horizontal
(21-percent slope) or greater. For roof slopes from
21/2 units vertical in 12 units horizontal (21-percent slope) to
four units vertical in 12 units horizontal (33-percent slope),
double underlayment application is required in accordance
with Section 1507.3.3.

Underlayment. Unless otherwise noted, required
underlayment shall conform to: ASTM D 226, Type II;
ASTMD2626 orASTMD6380, ClassMmineral-surfaced
roll roofing.

Low-slope roofs. For roof slopes from 21/2
units vertical in 12 units horizontal (21-percent slope),
up to four units vertical in 12 units horizontal (33-percent
slope), underlayment shall be a minimum of two layers
applied as follows:
1. Starting at the eave, a 19-inch (483 mm) strip of
underlayment shall be applied parallel with the
eave and fastened sufficiently in place.
2. Starting at the eave, 36-inch-wide (914 mm) strips
of underlayment felt shall be applied overlapping
successive sheets 19 inches (483 mm) and fastened
sufficiently in place.

High-slope roofs. For roof slopes of four
units vertical in 12 units horizontal (33-percent slope) or
greater, underlayment shall be a minimum of one layer of
underlayment felt applied shingle fashion, parallel to,
and starting from the eaves and lapped 2 inches (51 mm),
fastened only as necessary to hold in place.

Clay tile. Clay roof tile shall comply with ASTM
C 1167.
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ROOF ASSEMBLIES AND ROOFTOP STRUCTURES

Concrete tile. Concrete roof tile shall comply
with ASTM C 1492.

Fasteners. Tile fasteners shall be corrosion resistant
and not less than 11 gage, 5/16-inch (8.0 mm) head, and
of sufficient length to penetrate the deck a minimum of 0.75
inch (19.1 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 (2.1 mm). Perimeter fastening
areas include three tile courses but not less than 36 inches
(914 mm) from either side of hips or ridges and edges of
eaves and gable rakes.

Attachment. Clay and concrete roof tiles shall be
fastened in accordance with Table 1507.3.7.

Application. Tile shall be applied according to the
manufacturer’s installation instructions, based on the following:
1. Climatic conditions.
2. Roof slope.
3. Underlayment system.
4. Type of tile being installed.

Flashing. At the juncture of the roof vertical surfaces,
flashing and counterflashing shall be provided in
accordance with the manufacturer’s installation instructions,
and where of metal, shall not be less than 0.019-inch
(0.48 mm) (No. 26 galvanized sheet gage) corrosion-resistant
metal. The valley flashing shall extend at least 11 inches
(279 mm) from the centerline each way and have a splash
diverter rib not less than 1 inch (25 mm) high at the flowline
formed as part of the flashing. Sections of flashing shall
have an end lap of not less than 4 inches (102 mm). For roof
slopes of three units vertical in 12 units horizontal (25-percent
slope) and over, the valley flashing shall have a
36-inch-wide (914 mm) underlayment of either one layer of
Type I underlayment running the full length of the valley, or
a self-adhering polymer-modified bitumen sheet complying
with ASTM D 1970, in addition to other required
underlayment. In areas where the average daily temperature
in January is 25F (-4C) or less or where there is a possibility
of ice forming along the eaves causing a backup ofwater,
the metal valley flashing underlayment shall be solid
cemented to the roofing underlayment for slopes under
seven units vertical in 12 units horizontal (58-percent slope)
or self-adhering polymer-modified bitumen sheet shall be
installed.

International Building Code 1507.3.1

Deck requirements. Concrete and clay tile shall
be installed only over solid sheathing or spaced structural
sheathing boards.

International Building Code 1507.3.2

Deck slope. Clay and concrete roof tile shall be
installed on roof slopes of 21/2 units vertical in 12 units horizontal
(21-percent slope) or greater. For roof slopes from
21/2 units vertical in 12 units horizontal (21-percent slope) to
four units vertical in 12 units horizontal (33-percent slope),
double underlayment application is required in accordance
with Section 1507.3.3.

International Building Code 1507.3.3

Underlayment. Unless otherwise noted, required
underlayment shall conform to: ASTM D 226, Type II;
ASTMD2626 orASTMD6380, ClassMmineral-surfaced
roll roofing.

Low-slope roofs. For roof slopes from 21/2
units vertical in 12 units horizontal (21-percent slope),
up to four units vertical in 12 units horizontal (33-percent
slope), underlayment shall be a minimum of two layers
applied as follows:
1. Starting at the eave, a 19-inch (483 mm) strip of
underlayment shall be applied parallel with the
eave and fastened sufficiently in place.
2. Starting at the eave, 36-inch-wide (914 mm) strips
of underlayment felt shall be applied overlapping
successive sheets 19 inches (483 mm) and fastened
sufficiently in place.

High-slope roofs. For roof slopes of four
units vertical in 12 units horizontal (33-percent slope) or
greater, underlayment shall be a minimum of one layer of
underlayment felt applied shingle fashion, parallel to,
and starting from the eaves and lapped 2 inches (51 mm),
fastened only as necessary to hold in place.

International Building Code 1507.3.3.1

Low-slope roofs. For roof slopes from 21/2
units vertical in 12 units horizontal (21-percent slope),
up to four units vertical in 12 units horizontal (33-percent
slope), underlayment shall be a minimum of two layers
applied as follows:
1. Starting at the eave, a 19-inch (483 mm) strip of
underlayment shall be applied parallel with the
eave and fastened sufficiently in place.
2. Starting at the eave, 36-inch-wide (914 mm) strips
of underlayment felt shall be applied overlapping
successive sheets 19 inches (483 mm) and fastened
sufficiently in place.

International Building Code 1507.3.3.2

High-slope roofs. For roof slopes of four
units vertical in 12 units horizontal (33-percent slope) or
greater, underlayment shall be a minimum of one layer of
underlayment felt applied shingle fashion, parallel to,
and starting from the eaves and lapped 2 inches (51 mm),
fastened only as necessary to hold in place.

International Building Code 1507.3.4

Clay tile. Clay roof tile shall comply with ASTM
C 1167.
2006 INTERNATIONAL BUILDING CODE 267
ROOF ASSEMBLIES AND ROOFTOP STRUCTURES

International Building Code 1507.3.5

Concrete tile. Concrete roof tile shall comply
with ASTM C 1492.

International Building Code 1507.3.6

Fasteners. Tile fasteners shall be corrosion resistant
and not less than 11 gage, 5/16-inch (8.0 mm) head, and
of sufficient length to penetrate the deck a minimum of 0.75
inch (19.1 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 (2.1 mm). Perimeter fastening
areas include three tile courses but not less than 36 inches
(914 mm) from either side of hips or ridges and edges of
eaves and gable rakes.

International Building Code 1507.3.7

Attachment. Clay and concrete roof tiles shall be
fastened in accordance with Table 1507.3.7.

International Building Code 1507.3.8

Application. Tile shall be applied according to the
manufacturer’s installation instructions, based on the following:
1. Climatic conditions.
2. Roof slope.
3. Underlayment system.
4. Type of tile being installed.

International Building Code 1507.3.9

Flashing. At the juncture of the roof vertical surfaces,
flashing and counterflashing shall be provided in
accordance with the manufacturer’s installation instructions,
and where of metal, shall not be less than 0.019-inch
(0.48 mm) (No. 26 galvanized sheet gage) corrosion-resistant
metal. The valley flashing shall extend at least 11 inches
(279 mm) from the centerline each way and have a splash
diverter rib not less than 1 inch (25 mm) high at the flowline
formed as part of the flashing. Sections of flashing shall
have an end lap of not less than 4 inches (102 mm). For roof
slopes of three units vertical in 12 units horizontal (25-percent
slope) and over, the valley flashing shall have a
36-inch-wide (914 mm) underlayment of either one layer of
Type I underlayment running the full length of the valley, or
a self-adhering polymer-modified bitumen sheet complying
with ASTM D 1970, in addition to other required
underlayment. In areas where the average daily temperature
in January is 25F (-4C) or less or where there is a possibility
of ice forming along the eaves causing a backup ofwater,
the metal valley flashing underlayment shall be solid
cemented to the roofing underlayment for slopes under
seven units vertical in 12 units horizontal (58-percent slope)
or self-adhering polymer-modified bitumen sheet shall be
installed.

International Building Code 1507.4

Metal roof panels. The installation of metal roof panels
shall comply with the provisions of this section.

Deck requirements. Metal roof panel roof coverings
shall be applied to a solid or closely fitted deck, except
where the roof covering is specifically designed to be
applied to spaced supports.

Deck slope. Minimum slopes for metal roof panels
shall comply with the following:
1. The minimum slope for lapped, nonsoldered seam
metal roofs without applied lap sealant shall be three
units vertical in 12 units horizontal (25-percent
slope).
2. The minimum slope for lapped, nonsoldered seam
metal roofs with applied lap sealant shall be one-half
unit vertical in 12 units horizontal (4-percent slope).
Lap sealants shall be applied in accordance with the
approved manufacturer’s installation instructions.
3. The minimum slope for standing seam of roof systems
shall be one-quarter unit vertical in 12 units horizontal
(2-percent slope).

Material standards. Metal-sheet roof covering
systems that incorporate supporting structural members
shall be designed in accordance with Chapter 22.
Metal-sheet roof coverings installed over structural decking
shall comply with Table 1507.4.3.(1). The materials used
for metal-sheet roof coverings shall be naturally corrosion
resistant or provided with corrosion resistance in accordance
with the standards and minimum thicknesses shown
in Table 1507.4.3(2).

Attachment. Metal roof panels shall be secured to
the supports in accordance with the approved manufacturer’s
fasteners. In the absence of manufacturer recommendations,
the following fasteners shall be used:
1. Galvanized fasteners shall be used for steel roofs.
2. 300 series stainless-steel fasteners shall be used for
copper roofs.
3. Stainless-steel fasteners are acceptable for all types of
metal roofs.

International Building Code 1507.4.1

Deck requirements. Metal roof panel roof coverings
shall be applied to a solid or closely fitted deck, except
where the roof covering is specifically designed to be
applied to spaced supports.

International Building Code 1507.4.2

Deck slope. Minimum slopes for metal roof panels
shall comply with the following:
1. The minimum slope for lapped, nonsoldered seam
metal roofs without applied lap sealant shall be three
units vertical in 12 units horizontal (25-percent
slope).
2. The minimum slope for lapped, nonsoldered seam
metal roofs with applied lap sealant shall be one-half
unit vertical in 12 units horizontal (4-percent slope).
Lap sealants shall be applied in accordance with the
approved manufacturer’s installation instructions.
3. The minimum slope for standing seam of roof systems
shall be one-quarter unit vertical in 12 units horizontal
(2-percent slope).

International Building Code 1507.4.3

Material standards. Metal-sheet roof covering
systems that incorporate supporting structural members
shall be designed in accordance with Chapter 22.
Metal-sheet roof coverings installed over structural decking
shall comply with Table 1507.4.3.(1). The materials used
for metal-sheet roof coverings shall be naturally corrosion
resistant or provided with corrosion resistance in accordance
with the standards and minimum thicknesses shown
in Table 1507.4.3(2).

International Building Code 1507.4.4

Attachment. Metal roof panels shall be secured to
the supports in accordance with the approved manufacturer’s
fasteners. In the absence of manufacturer recommendations,
the following fasteners shall be used:
1. Galvanized fasteners shall be used for steel roofs.
2. 300 series stainless-steel fasteners shall be used for
copper roofs.
3. Stainless-steel fasteners are acceptable for all types of
metal roofs.

International Building Code 1507.5

Metal roof shingles. The installation of metal roof
shingles shall comply with the provisions of this section.

Deck requirements. Metal roof shingles shall be
applied to a solid or closely fitted deck, except where the
roof covering is specifically designed to be applied to
spaced sheathing.

Deck slope. Metal roof shingles shall not be
installed on roof slopes belowthree units vertical in 12 units
horizontal (25-percent slope).

Underlayment. Underlayment shall comply with
ASTMD226, Type I orASTMD4869. In areas where there
has been a history of ice forming along the eaves causing a
backup of water, an ice barrier that consists of at least two
layers of underlayment cemented together or of a
self-adhering polymer-modified bitumen sheet shall be
used in lieu of normal underlayment and extend from the
eave’s edge to a point at least 24 inches (610 mm) inside the
exterior wall line of the building.
Exception: Detached accessory structures that contain
no conditioned floor area.

Material standards. Metal roof shingle roof coverings
shall comply with Table 1507.4.3(1). The materials
used for metal-roof shingle roof coverings shall be naturally
corrosion resistant or provided with corrosion resistance in
accordance with the standards and minimum thicknesses
specified in the standards listed in Table 1507.4.3(2).

Attachment. Metal roof shingles shall be secured
to the roof in accordance with the approved manufacturer’s
installation instructions.
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Flashing. Roof valley flashing shall be of corrosion-
resistant metal of the same material as the roof covering
or shall comply with the standards in Table 1507.4.3(1).
The valley flashing shall extend at least 8 inches (203 mm)
from the centerline eachway and shall have a splash diverter
rib not less than 0.75 inch (19.1 mm) high at the flow line
formed as part of the flashing. Sections of flashing shall
have an end lap of not less than 4 inches (102 mm). In areas
where the average daily temperature in January is 25F
(-4C) or less or where there is a possibility of ice forming
along the eaves causing a backup of water, the metal valley
flashing shall have a 36-inch-wide (914 mm) underlayment
directly under it consisting of either one layer of
underlayment running the full length of the valley or a
self-adhering polymer-modified bitumen sheet complying
with ASTM D 1970, in addition to underlayment required
for metal roof shingles. The metal valley flashing
underlayment shall be solidly cemented to the roofing
underlayment for roof slopes under seven units vertical in
12 units horizontal (58-percent slope) or self-adhering polymer-
modified bitumen sheet shall be installed.

International Building Code 1507.5.1

Deck requirements. Metal roof shingles shall be
applied to a solid or closely fitted deck, except where the
roof covering is specifically designed to be applied to
spaced sheathing.

International Building Code 1507.5.2

Deck slope. Metal roof shingles shall not be
installed on roof slopes belowthree units vertical in 12 units
horizontal (25-percent slope).

International Building Code 1507.5.3

Underlayment. Underlayment shall comply with
ASTMD226, Type I orASTMD4869. In areas where there
has been a history of ice forming along the eaves causing a
backup of water, an ice barrier that consists of at least two
layers of underlayment cemented together or of a
self-adhering polymer-modified bitumen sheet shall be
used in lieu of normal underlayment and extend from the
eave’s edge to a point at least 24 inches (610 mm) inside the
exterior wall line of the building.
Exception: Detached accessory structures that contain
no conditioned floor area.

International Building Code 1507.5.4

Material standards. Metal roof shingle roof coverings
shall comply with Table 1507.4.3(1). The materials
used for metal-roof shingle roof coverings shall be naturally
corrosion resistant or provided with corrosion resistance in
accordance with the standards and minimum thicknesses
specified in the standards listed in Table 1507.4.3(2).

International Building Code 1507.5.5

Attachment. Metal roof shingles shall be secured
to the roof in accordance with the approved manufacturer’s
installation instructions.
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International Building Code 1507.5.6

Flashing. Roof valley flashing shall be of corrosion-
resistant metal of the same material as the roof covering
or shall comply with the standards in Table 1507.4.3(1).
The valley flashing shall extend at least 8 inches (203 mm)
from the centerline eachway and shall have a splash diverter
rib not less than 0.75 inch (19.1 mm) high at the flow line
formed as part of the flashing. Sections of flashing shall
have an end lap of not less than 4 inches (102 mm). In areas
where the average daily temperature in January is 25F
(-4C) or less or where there is a possibility of ice forming
along the eaves causing a backup of water, the metal valley
flashing shall have a 36-inch-wide (914 mm) underlayment
directly under it consisting of either one layer of
underlayment running the full length of the valley or a
self-adhering polymer-modified bitumen sheet complying
with ASTM D 1970, in addition to underlayment required
for metal roof shingles. The metal valley flashing
underlayment shall be solidly cemented to the roofing
underlayment for roof slopes under seven units vertical in
12 units horizontal (58-percent slope) or self-adhering polymer-
modified bitumen sheet shall be installed.

International Building Code 1507.6

Mineral-surfaced roll roofing. The installation of
mineral-surfaced roll roofing shall comply with this section.

Deck requirements. Mineral-surfaced roll roofing
shall be fastened to solidly sheathed roofs.

Deck slope. Mineral-surfaced roll roofing shall
not be applied on roof slopes below one unit vertical in 12
units horizontal (8-percent slope).

Underlayment. Underlayment shall comply with
ASTMD226, Type I orASTMD4869. In areas where there
has been a history of ice forming along the eaves causing a
backup of water, an ice barrier that consists of at least two
layers of underlayment cemented together or of a
self-adhering polymer-modified bitumen sheet shall be
used in lieu of normal underlayment and extend from the
eave’s edge to a point at least 24 inches (610 mm) inside the
exterior wall line of the building.
Exception: Detached accessory structures that contain
no conditioned floor area.

Material standards. Mineral-surfaced roll roofing
shall conform to ASTM D 3909 or ASTM D 6380.

International Building Code 1507.6.1

Deck requirements. Mineral-surfaced roll roofing
shall be fastened to solidly sheathed roofs.

International Building Code 1507.6.2

Deck slope. Mineral-surfaced roll roofing shall
not be applied on roof slopes below one unit vertical in 12
units horizontal (8-percent slope).

International Building Code 1507.6.3

Underlayment. Underlayment shall comply with
ASTMD226, Type I orASTMD4869. In areas where there
has been a history of ice forming along the eaves causing a
backup of water, an ice barrier that consists of at least two
layers of underlayment cemented together or of a
self-adhering polymer-modified bitumen sheet shall be
used in lieu of normal underlayment and extend from the
eave’s edge to a point at least 24 inches (610 mm) inside the
exterior wall line of the building.
Exception: Detached accessory structures that contain
no conditioned floor area.

International Building Code 1507.6.4

Material standards. Mineral-surfaced roll roofing
shall conform to ASTM D 3909 or ASTM D 6380.

International Building Code 1507.7

Slate shingles. The installation of slate shingles shall
comply with the provisions of this section.

Deck requirements. Slate shingles shall be fastened
to solidly sheathed roofs.

Deck slope. Slate shingles shall only be used on
slopes of four units vertical in 12 units horizontal (4:12) or
greater.

Underlayment. Underlayment shall comply with
ASTM D 226, Type I or ASTM D 4869. In areas where the
average daily temperature in January is 25F (-4C) or less
or where there is a possibility of ice forming along the eaves
causing a backup of water, an ice barrier that consists of at
least two layers of underlayment cemented together or of a
self-adhering polymer-modified bitumen sheet shall extend
from the eave’s edge to a point at least 24 inches (610 mm)
inside the exterior wall line of the building.
Exception: Detached accessory structures that contain
no conditioned floor area.

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Material standards. Slate shingles shall comply
with ASTM C 406.

Application. Minimum headlap for slate shingles
shall be in accordance with Table 1507.7.5. Slate shingles
shall be secured to the roof with two fasteners per slate.

Flashing. Flashing and counterflashing shall be
made with sheet metal. Valley flashing shall be a minimum
of 15 inches (381 mm) wide.Valley and flashing metal shall
be a minimum uncoated thickness of 0.0179-inch (0.455
mm) zinc-coated G90. Chimneys, stucco or brick walls
shall have a minimum of two plies of felt for a cap flashing
consisting of a 4-inch-wide (102 mm) strip of felt set in plastic
cement and extending 1 inch (25 mm) above the first felt
and a top coating of plastic cement. The felt shall extend
over the base flashing 2 inches (51 mm).

International Building Code 1507.7.1

Deck requirements. Slate shingles shall be fastened
to solidly sheathed roofs.

International Building Code 1507.7.2

Deck slope. Slate shingles shall only be used on
slopes of four units vertical in 12 units horizontal (4:12) or
greater.

International Building Code 1507.7.3

Underlayment. Underlayment shall comply with
ASTM D 226, Type I or ASTM D 4869. In areas where the
average daily temperature in January is 25F (-4C) or less
or where there is a possibility of ice forming along the eaves
causing a backup of water, an ice barrier that consists of at
least two layers of underlayment cemented together or of a
self-adhering polymer-modified bitumen sheet shall extend
from the eave’s edge to a point at least 24 inches (610 mm)
inside the exterior wall line of the building.
Exception: Detached accessory structures that contain
no conditioned floor area.

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International Building Code 1507.7.4

Material standards. Slate shingles shall comply
with ASTM C 406.

International Building Code 1507.7.5

Application. Minimum headlap for slate shingles
shall be in accordance with Table 1507.7.5. Slate shingles
shall be secured to the roof with two fasteners per slate.

International Building Code 1507.7.6

Flashing. Flashing and counterflashing shall be
made with sheet metal. Valley flashing shall be a minimum
of 15 inches (381 mm) wide.Valley and flashing metal shall
be a minimum uncoated thickness of 0.0179-inch (0.455
mm) zinc-coated G90. Chimneys, stucco or brick walls
shall have a minimum of two plies of felt for a cap flashing
consisting of a 4-inch-wide (102 mm) strip of felt set in plastic
cement and extending 1 inch (25 mm) above the first felt
and a top coating of plastic cement. The felt shall extend
over the base flashing 2 inches (51 mm).

International Building Code 1507.8

Wood shingles. The installation of wood shingles shall
comply with the provisions of this section and Table 1507.8.

Deck requirements. Wood shingles shall be
installed on solid or spaced sheathing. Where spaced
sheathing is used, sheathing boards shall not be less than
1-inch by 4-inch (25 mm by 102 mm) nominal dimensions
and shall be spaced on centers equal to the weather exposure
to coincide with the placement of fasteners.

Solid sheathing required. Solid sheathing is
required in areas where the average daily temperature in
January is 25F (-4C) or less or where there is a possibility
of ice forming along the eaves causing a backup of
water.

Deck slope. Wood shingles shall be installed on
slopes of three units vertical in 12 units horizontal (25-percent
slope) or greater.

Underlayment. Underlayment shall comply with
ASTMD226, Type I orASTMD4869. In areas where there
has been a history of ice forming along the eaves causing a
backup of water, an ice barrier that consists of at least two
layers of underlayment cemented together or of a
self-adhering polymer-modified bitumen sheet shall be
used in lieu of normal underlayment and extend from the
eave’s edge to a point at least 24 inches (610 mm) inside the
exterior wall line of the building.
Exception: Detached accessory structures that contain
no conditioned floor area.

Material standards. Wood shingles shall be of
naturally durable wood and comply with the requirements
of Table 1507.8.4.

Attachment. Fasteners for wood shingles shall be
corrosion resistant with a minimum penetration of 0.75 inch
(19.1 mm) into the sheathing. For sheathing less than 0.5
inch (12.7 mm) in thickness, the fasteners shall extend
through the sheathing. Each shingle shall be attached with a
minimum of two fasteners.

Application. Wood shingles shall be laid with a
side lap not less than 1.5 inches (38 mm) between joints in
adjacent courses, and not be in direct alignment in alternate
courses. Spacing between shingles shall be 0.25 to 0.375
inches (6.4 to 9.5 mm).Weather exposure forwood shingles
shall not exceed that set in Table 1507.8.6.

Flashing. At the juncture of the roof and vertical surfaces,
flashing and counterflashing shall be provided in accordance
with the manufacturer’s installation instructions, and
where ofmetal, shall not be less than 0.019-inch (0.48mm)(No.
26 galvanized sheet gage) corrosion-resistant metal. The valley
flashing shall extend at least 11 inches (279 mm) from the centerline
each way and have a splash diverter rib not less than 1
inch (25mm)high at the flowline formed as part of the flashing.
Sections of flashing shall have an end lap of not less than 4
inches (102 mm). For roof slopes of three units vertical in 12
units horizontal (25-percent slope) and over, the valley flashing
shall have a 36-inch-wide (914 mm) underlayment of
either one layer of Type I underlayment running the full
length of the valley or a self-adhering polymer-modified bitumen
sheet complying with ASTM D 1970, in addition to
other required underlayment. In areas where the average
daily temperature in January is 25F (-4C) or less or where
there is a possibility of ice forming along the eaves causing a
backup ofwater, themetal valley flashing underlayment shall
be solidly cemented to the roofing underlayment for slopes
under seven units vertical in 12 units horizontal (58-percent
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slope) or self-adhering polymer-modified bitumen sheet
shall be installed.

International Building Code 1507.8.1

Deck requirements. Wood shingles shall be
installed on solid or spaced sheathing. Where spaced
sheathing is used, sheathing boards shall not be less than
1-inch by 4-inch (25 mm by 102 mm) nominal dimensions
and shall be spaced on centers equal to the weather exposure
to coincide with the placement of fasteners.

Solid sheathing required. Solid sheathing is
required in areas where the average daily temperature in
January is 25F (-4C) or less or where there is a possibility
of ice forming along the eaves causing a backup of
water.

International Building Code 1507.8.1.1

Solid sheathing required. Solid sheathing is
required in areas where the average daily temperature in
January is 25F (-4C) or less or where there is a possibility
of ice forming along the eaves causing a backup of
water.

International Building Code 1507.8.2

Deck slope. Wood shingles shall be installed on
slopes of three units vertical in 12 units horizontal (25-percent
slope) or greater.

International Building Code 1507.8.3

Underlayment. Underlayment shall comply with
ASTMD226, Type I orASTMD4869. In areas where there
has been a history of ice forming along the eaves causing a
backup of water, an ice barrier that consists of at least two
layers of underlayment cemented together or of a
self-adhering polymer-modified bitumen sheet shall be
used in lieu of normal underlayment and extend from the
eave’s edge to a point at least 24 inches (610 mm) inside the
exterior wall line of the building.
Exception: Detached accessory structures that contain
no conditioned floor area.

International Building Code 1507.8.4

Material standards. Wood shingles shall be of
naturally durable wood and comply with the requirements
of Table 1507.8.4.

International Building Code 1507.8.5

Attachment. Fasteners for wood shingles shall be
corrosion resistant with a minimum penetration of 0.75 inch
(19.1 mm) into the sheathing. For sheathing less than 0.5
inch (12.7 mm) in thickness, the fasteners shall extend
through the sheathing. Each shingle shall be attached with a
minimum of two fasteners.

International Building Code 1507.8.6

Application. Wood shingles shall be laid with a
side lap not less than 1.5 inches (38 mm) between joints in
adjacent courses, and not be in direct alignment in alternate
courses. Spacing between shingles shall be 0.25 to 0.375
inches (6.4 to 9.5 mm).Weather exposure forwood shingles
shall not exceed that set in Table 1507.8.6.

International Building Code 1507.8.7

Flashing. At the juncture of the roof and vertical surfaces,
flashing and counterflashing shall be provided in accordance
with the manufacturer’s installation instructions, and
where ofmetal, shall not be less than 0.019-inch (0.48mm)(No.
26 galvanized sheet gage) corrosion-resistant metal. The valley
flashing shall extend at least 11 inches (279 mm) from the centerline
each way and have a splash diverter rib not less than 1
inch (25mm)high at the flowline formed as part of the flashing.
Sections of flashing shall have an end lap of not less than 4
inches (102 mm). For roof slopes of three units vertical in 12
units horizontal (25-percent slope) and over, the valley flashing
shall have a 36-inch-wide (914 mm) underlayment of
either one layer of Type I underlayment running the full
length of the valley or a self-adhering polymer-modified bitumen
sheet complying with ASTM D 1970, in addition to
other required underlayment. In areas where the average
daily temperature in January is 25F (-4C) or less or where
there is a possibility of ice forming along the eaves causing a
backup ofwater, themetal valley flashing underlayment shall
be solidly cemented to the roofing underlayment for slopes
under seven units vertical in 12 units horizontal (58-percent
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slope) or self-adhering polymer-modified bitumen sheet
shall be installed.

International Building Code 1507.9

Wood shakes. The installation of wood shakes shall
comply with the provisions of this section and Table 1507.8.

Deck requirements. Wood shakes shall only be
used on solid or spaced sheathing. Where spaced sheathing is
used, sheathing boards shall not be less than 1-inch by 4-inch
(25mmby 102 mm) nominal dimensions and shall be spaced
on centers equal to the weather exposure to coincide with the
placement of fasteners. Where 1-inch by 4-inch (25 mm by
102 mm) spaced sheathing is installed at 10 inches (254 mm)
o.c., additional 1-inch by 4-inch (25 mm by 102 mm) boards
shall be installed between the sheathing boards.
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Solid sheathing required. Solid sheathing is
required in areas where the average daily temperature in
January is 25F (-4C) or less or where there is a possibility
of ice forming along the eaves causing a backup of
water.

Deck slope. Wood shakes shall only be used on
slopes of four units vertical in 12 units horizontal (33-percent
slope) or greater

Underlayment. Underlayment shall comply with
ASTMD226, Type I orASTMD4869. In areas where there
has been a history of ice forming along the eaves causing a
backup of water, an ice barrier that consists of at least two
layers of underlayment cemented together or of a
self-adhering polymer-modified bitumen sheet shall be
used in lieu of normal underlayment and extend from the
eave’s edge to a point at least 24 inches (610 mm) inside the
exterior wall line of the building.
Exception: Detached accessory structures that contain
no conditioned floor area.

Interlayment. Interlayment shall comply with
ASTM D 226, Type I.

Material standards. Wood shakes shall comply
with the requirements of Table 1507.9.5.

Attachment. Fasteners for wood shakes shall be
corrosion resistant with a minimum penetration of 0.75 inch
(19.1 mm) into the sheathing. For sheathing less than 0.5
inch (12.7 mm) in thickness, the fasteners shall extend
through the sheathing. Each shake shall be attached with a
minimum of two fasteners.

Application.Wood shakes shall be laid with a side
lap not less than 1.5 inches (38 mm) between joints in adjacent
courses. Spacing between shakes in the same course
shall be 0.375 to 0.625 inches (9.5 to 15.9 mm) for shakes
and taper sawn shakes of naturally durable wood and shall
be 0.25 to 0.375 inch (6.4 to 9.5 mm) for preservative taper
sawn shakes. Weather exposure for wood shakes shall not
exceed those set in Table 1507.9.7.

Flashing. At the juncture of the roof and vertical
surfaces, flashing and counterflashing shall be provided in
accordance with the manufacturer’s installation instructions,
and where of metal, shall not be less than 0.019-inch
(0.48 mm) (No. 26 galvanized sheet gage) corrosion-resistant
metal. The valley flashing shall extend at least 11 inches
(279 mm) from the centerline each way and have a splash
diverter rib not less than 1 inch (25 mm) high at the flowline
formed as part of the flashing. Sections of flashing shall
have an end lap of not less than 4 inches (102 mm). For roof
slopes of three units vertical in 12 units horizontal (25-percent
slope) and over, the valley flashing shall have a
36-inch-wide (914 mm) underlayment of either one layer of
Type I underlayment running the full length of the valley or
a self-adhering polymer-modified bitumen sheet complying
with ASTM D 1970, in addition to other required
underlayment. In areas where the average daily temperature
in January is 25F (-4C) or less or where there is a possibility
of ice forming along the eaves causing a backup ofwater,
the metal valley flashing underlayment shall be solidly
cemented to the roofing underlayment for slopes under
seven units vertical in 12 units horizontal (58-percent slope)
or self-adhering polymer-modified bitumen sheet shall be
installed.

International Building Code 1507.9.1.1

Solid sheathing required. Solid sheathing is
required in areas where the average daily temperature in
January is 25F (-4C) or less or where there is a possibility
of ice forming along the eaves causing a backup of
water.

International Building Code 1507.9.2

Deck slope. Wood shakes shall only be used on
slopes of four units vertical in 12 units horizontal (33-percent
slope) or greater

International Building Code 1507.9.3

Underlayment. Underlayment shall comply with
ASTMD226, Type I orASTMD4869. In areas where there
has been a history of ice forming along the eaves causing a
backup of water, an ice barrier that consists of at least two
layers of underlayment cemented together or of a
self-adhering polymer-modified bitumen sheet shall be
used in lieu of normal underlayment and extend from the
eave’s edge to a point at least 24 inches (610 mm) inside the
exterior wall line of the building.
Exception: Detached accessory structures that contain
no conditioned floor area.

International Building Code 1507.9.4

Interlayment. Interlayment shall comply with
ASTM D 226, Type I.

International Building Code 1507.9.5

Material standards. Wood shakes shall comply
with the requirements of Table 1507.9.5.

International Building Code 1507.9.6

Attachment. Fasteners for wood shakes shall be
corrosion resistant with a minimum penetration of 0.75 inch
(19.1 mm) into the sheathing. For sheathing less than 0.5
inch (12.7 mm) in thickness, the fasteners shall extend
through the sheathing. Each shake shall be attached with a
minimum of two fasteners.

International Building Code 1507.9.7

Application.Wood shakes shall be laid with a side
lap not less than 1.5 inches (38 mm) between joints in adjacent
courses. Spacing between shakes in the same course
shall be 0.375 to 0.625 inches (9.5 to 15.9 mm) for shakes
and taper sawn shakes of naturally durable wood and shall
be 0.25 to 0.375 inch (6.4 to 9.5 mm) for preservative taper
sawn shakes. Weather exposure for wood shakes shall not
exceed those set in Table 1507.9.7.

International Building Code 1507.9.8

Flashing. At the juncture of the roof and vertical
surfaces, flashing and counterflashing shall be provided in
accordance with the manufacturer’s installation instructions,
and where of metal, shall not be less than 0.019-inch
(0.48 mm) (No. 26 galvanized sheet gage) corrosion-resistant
metal. The valley flashing shall extend at least 11 inches
(279 mm) from the centerline each way and have a splash
diverter rib not less than 1 inch (25 mm) high at the flowline
formed as part of the flashing. Sections of flashing shall
have an end lap of not less than 4 inches (102 mm). For roof
slopes of three units vertical in 12 units horizontal (25-percent
slope) and over, the valley flashing shall have a
36-inch-wide (914 mm) underlayment of either one layer of
Type I underlayment running the full length of the valley or
a self-adhering polymer-modified bitumen sheet complying
with ASTM D 1970, in addition to other required
underlayment. In areas where the average daily temperature
in January is 25F (-4C) or less or where there is a possibility
of ice forming along the eaves causing a backup ofwater,
the metal valley flashing underlayment shall be solidly
cemented to the roofing underlayment for slopes under
seven units vertical in 12 units horizontal (58-percent slope)
or self-adhering polymer-modified bitumen sheet shall be
installed.

International Building Code section1507.9.1

Deck requirements. Wood shakes shall only be
used on solid or spaced sheathing. Where spaced sheathing is
used, sheathing boards shall not be less than 1-inch by 4-inch
(25mmby 102 mm) nominal dimensions and shall be spaced
on centers equal to the weather exposure to coincide with the
placement of fasteners. Where 1-inch by 4-inch (25 mm by
102 mm) spaced sheathing is installed at 10 inches (254 mm)
o.c., additional 1-inch by 4-inch (25 mm by 102 mm) boards
shall be installed between the sheathing boards.
272 2006 INTERNATIONAL BUILDING CODE
ROOF ASSEMBLIES AND ROOFTOP STRUCTURES

Solid sheathing required. Solid sheathing is
required in areas where the average daily temperature in
January is 25F (-4C) or less or where there is a possibility
of ice forming along the eaves causing a backup of
water.