CRC · California Residential Code
Sheathing, underlayment and fastening
This hub explains where the CRC sets material, underlayment and fastening requirements for roof and wall sheathing and points to the governing sections and tables.
Last reviewed: July 6, 2026
Overview
This section of the California Residential Code (CRC) covers the materials, attachment and application rules for roof and wall sheathing, the underlayment systems that go over decking, and the fastener types, sizes and spacing required to secure them. It brings together panel and board sheathing schedules, underlayment application (single vs. double layer and ice barriers), and roof‑covering–specific fastening details so that decks, roof coverings and claddings perform for wind, weather and load conditions (see §R905.1.1 for underlayment application and ice‑barrier rules).
Key mandatory tables and schedules include the sheathing fastener tables (Table R602.3(2) / Table R602.3(3)) that specify nail/staple types, penetration and edge/field spacing for wall and roof panels, and the roof‑covering sections (for example §R905.2 for asphalt shingles, §R905.3 for clay/concrete tile) that reference underlayment and attachment requirements. These tables set typical spacing such as 6" or 12" o.c. at supports and more restrictive spacing at edges or in high wind exposures.
For underlayment fastenings and cap‑nail requirements (mechanically fastened underlayment for certain asphalt shingle installations), consult the underlayment fastening table and related requirements in the building code (Table 1507.1.1(3)) and the CRC roof sections cited above for how wind speed, cap nails and self‑adhering products are treated.
In this section
Code references
Grounded in the retrieved California Residential Code — click a citation to read the verbatim passage:
CRC § 0.42 High relevance — show source text
Nails or staples shall be spaced at not more than 12
inches on center at intermediate supports for floors.
d. Fasteners shall be placed in a grid pattern throughout the body of the panel.
e. For 5-ply panels, intermediate nails shall be spaced not more than 12 inches on center each way.
f. Hardboard underlayment shall conform to CPA/ANSI A135.4.
g. Alternate fastening is only permitted for roof sheathing where the ultimate design wind speed is less than or equal to 110 mph, and where fasteners are installed 3 inches on
center at all supports, and where fastening is to wood framing of a species with specific gravity greater than or equal to 0.42 in accordance with AWC NDS.
h. Fiber-cement underlayment shall conform to ASTM C1288 or ISO 8336, Category C.|For SI: 1 inch = 25.4 mm.
a. Nail is a general description and shall be permitted to be T-head, modified round head or round head.
b. Staples shall have a minimum crown width of7/16-inch except as noted.
c. Nails or staples shall be spaced at not more than 6 inches on center at all supports where spans are 48 inches or greater. Nails or staples shall be spaced at not more than 12
inches on center at intermediate supports for floors.
d. Fasteners shall be placed in a grid pattern throughout the body of the panel.
e. For 5-ply panels, intermediate nails shall be spaced not more than 12 inches on center each way.
f. Hardboard underlayment shall conform to CPA/ANSI A135.4.
g. Alternate fastening is only permitted for roof sheathing where the ultimate design wind speed is less than or equal to 110 mph, and where fasteners are installed 3 inches on
center at all supports, and where fastening is to wood framing of a species with specific gravity greater than or equal to 0.42 in accordance with AWC NDS.
h. Fiber-cement underlayment shall conform to ASTM C1288 or ISO 8336, Category C.|For SI: 1 inch = 25.4 mm.
a. Nail is a general description and shall be permitted to be T-head, modified round head or round head.
b. Staples shall have a minimum crown width of7/16-inch except as noted.
c. Nails or staples shall be spaced at not more than 6 inches on center at all supports where spans are 48 inches or greater. Nails or staples shall be spaced at not more than 12
inches on center at intermediate supports for floors.
d. Fasteners shall be placed in a grid pattern throughout the body of the panel.
e. For 5-ply panels, intermediate nails shall be spaced not more than 12 inches on center each way.
f. Hardboard underlayment shall conform to CPA/ANSI A135.4.
g. Alternate fastening is only permitted for roof sheathing where the ultimate design wind speed is less than or equal to 110 mph, and where fasteners are installed 3 inches on
center at all supports, and where fastening is to wood framing of a species with specific gravity greater than or equal to 0.42 in accordance with AWC NDS.
h. Fiber-cement underlayment shall conform to ASTM C1288 or ISO 8336, Category C.||TABLE R602.
CRC § 1507.1.1 High relevance — show source text
An approved
underlayment complying with Table 1507.1.1(1) for
the applicable roof covering and basic wind speed
shall be applied over the entire roof over the 4-inch-
wide membrane strips. Underlayment shall be
applied in accordance with this table using the
application requirements for where the maximum
basic wind speed is less than 130 mph.
3.
A single layer of self-adhering polymer modified
bitumen underlayment complying with ASTM
D1970, installed in accordance with the
underlayment and roof covering manufacturers’
installation instructions for the deck material, roof
ventilation configuration, and climate exposure of
the roof covering.| |For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 mile per hour = 0.447 m/s.|For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 mile per hour = 0.447 m/s.|For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 mile per hour = 0.447 m/s.|For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 mile per hour = 0.447 m/s.|2025 CALIFORNIA BUILDING CODE 15-9
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
ROOF ASSEMBLIES AND ROOFTOP STRUCTURES
TABLE 1507.1.1(3)—UNDERLAYMENT FASTENING Col2 Col3 Col4 ROOF COVERING SECTION MAXIMUM BASIC WIND SPEED,****V < 130 MPH IN
HURRICANE-PRONE REGIONS ORV < 140 MPH
OUTSIDE HURRICANE-PRONE REGIONSMAXIMUM BASIC WIND SPEED,****V ≥ 130 MPH IN
HURRICANE-PRONE REGIONS ORV ≥ 140 MPH
OUTSIDE HURRICANE-PRONE REGIONSAsphalt shingles 1507.2 Fastened sufficiently to hold in place Mechanically fastened underlayment shall be fastened
with corrosion-resistant fasteners in a grid pattern of
not greater than 12 inches horizontally and vertically
between side laps with a 6-inch spacing at side and end
laps. Mechanically fastened underlayment shall be
fastened using annular ring or deformed shank nails
with 1-inch diameter metal or plastic caps. Metal caps
shall have a thickness of not less than 32-gage (0.0134
inch) sheet metal. Power-driven metal caps shall have a
minimum thickness of 0.010 inch. Minimum thickness of
the outside edge of plastic caps shall be 0.035 inch. The
cap nail shank shall be not less than 0.083 inch. The cap
nail shank shall have a length sufficient to penetrate
through the roof sheathing or not less than3/4 inch into
the roof sheathing.CRC § 0.42 High relevance — show source text
Nail is a general description and shall be permitted to be T-head, modified round head or round head.
b. Staples shall have a minimum crown width of7/16-inch except as noted.
c. Nails or staples shall be spaced at not more than 6 inches on center at all supports where spans are 48 inches or greater. Nails or staples shall be spaced at not more than 12
inches on center at intermediate supports for floors.
d. Fasteners shall be placed in a grid pattern throughout the body of the panel.
e. For 5-ply panels, intermediate nails shall be spaced not more than 12 inches on center each way.
f. Hardboard underlayment shall conform to CPA/ANSI A135.4.
g. Alternate fastening is only permitted for roof sheathing where the ultimate design wind speed is less than or equal to 110 mph, and where fasteners are installed 3 inches on
center at all supports, and where fastening is to wood framing of a species with specific gravity greater than or equal to 0.42 in accordance with AWC NDS.
h. Fiber-cement underlayment shall conform to ASTM C1288 or ISO 8336, Category C.|For SI: 1 inch = 25.4 mm.
a. Nail is a general description and shall be permitted to be T-head, modified round head or round head.
b. Staples shall have a minimum crown width of7/16-inch except as noted.
c. Nails or staples shall be spaced at not more than 6 inches on center at all supports where spans are 48 inches or greater. Nails or staples shall be spaced at not more than 12
inches on center at intermediate supports for floors.
d. Fasteners shall be placed in a grid pattern throughout the body of the panel.
e. For 5-ply panels, intermediate nails shall be spaced not more than 12 inches on center each way.
f. Hardboard underlayment shall conform to CPA/ANSI A135.4.
g. Alternate fastening is only permitted for roof sheathing where the ultimate design wind speed is less than or equal to 110 mph, and where fasteners are installed 3 inches on
center at all supports, and where fastening is to wood framing of a species with specific gravity greater than or equal to 0.42 in accordance with AWC NDS.
h. Fiber-cement underlayment shall conform to ASTM C1288 or ISO 8336, Category C.|For SI: 1 inch = 25.4 mm.
a. Nail is a general description and shall be permitted to be T-head, modified round head or round head.
b. Staples shall have a minimum crown width of7/16-inch except as noted.
c. Nails or staples shall be spaced at not more than 6 inches on center at all supports where spans are 48 inches or greater. Nails or staples shall be spaced at not more than 12
inches on center at intermediate supports for floors.
d. Fasteners shall be placed in a grid pattern throughout the body of the panel.
e. For 5-ply panels, intermediate nails shall be spaced not more than 12 inches on center each way.
f. Hardboard underlayment shall conform to CPA/ANSI A135.4.
g.CRC § 1507.1.1. High relevance — show source text
Where 1″ × 4″ spaced sheathing is
installed at 10 inches, boards must be installed
between the sheathing boards.| |In areas where the average daily
temperature in January is 25°F or
less or where there is a possibility
of ice forming along the eaves
causing a backup of water.|Solid sheathing is required.|Solid sheathing is required.| |3. Interlayment|No requirements.|Interlayment shall comply with ASTM D226, Type 1.| |4. Underlayment|4. Underlayment|4. Underlayment| |Temperate climate|Underlayment shall comply with Section
1507.1.1.|Underlayment shall comply with Section 1507.1.1.| |5. Application|5. Application|5. Application| |Attachment|Fasteners for wood shingles shall be hot-
dipped galvanized or Type 304 (Type 316 for
coastal areas) stainless steel with a minimum
penetration of 0.75 inch into the sheathing.
For sheathing less than 0.5 inch thick, the
fasteners shall extend through the sheathing.|Fasteners for wood shakes shall be hot-dipped galva-
nized or Type 304 (Type 316 for coastal areas) with a
minimum penetration of 0.75 inch into the sheath-
ing. For sheathing less than 0.5 inch thick, the
fasteners shall extend through the sheathing.| |No. of fasteners|Two per shingle.|Two per shake.| |Exposure|Weather exposures shall not exceed those set
forth in Table 1507.8.7.|Weather exposures shall not exceed those set forth in
Table 1507.9.8.| |Method|Shingles shall be laid with a side lap of not
less than 1.5 inches between joints in courses,
and no two joints in any three adjacent
courses shall be in direct alignment. Spacing
between shingles shall be 0.25 to 0.375 inch.|Shakes shall be laid with a side lap of not less than
1.5 inches between joints in adjacent courses. Spac-
ing between shakes shall not be less than 0.375 inch
or more than 0.625 inch for shakes and taper sawn
shakes of naturally durable wood and shall be 0.25 to
0.375 inch for preservative-treated taper sawn
shakes.| |Flashing|In accordance with Section 1507.8.8.|In accordance with Section 1507.9.9.| |For SI: 1 inch = 25.4 mm, °C = [(°F) - 32]/1.8.|For SI: 1 inch = 25.4 mm, °C = [(°F) - 32]/1.8.|For SI: 1 inch = 25.4 mm, °C = [(°F) - 32]/1.8.|1507.8.1 Deck requirements. Wood shingles shall be installed on solid or spaced sheathing. Where spaced sheathing is used, sheathing boards shall be not 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.
CRC § 25.4 High relevance — show source text
Fiber-cement underlayment shall conform to ASTM C1288 or ISO 8336, Category C.|For SI: 1 inch = 25.4 mm.
a. Nail is a general description and shall be permitted to be T-head, modified round head or round head.
b. Staples shall have a minimum crown width of7/16-inch except as noted.
c. Nails or staples shall be spaced at not more than 6 inches on center at all supports where spans are 48 inches or greater. Nails or staples shall be spaced at not more than 12
inches on center at intermediate supports for floors.
d. Fasteners shall be placed in a grid pattern throughout the body of the panel.
e. For 5-ply panels, intermediate nails shall be spaced not more than 12 inches on center each way.
f. Hardboard underlayment shall conform to CPA/ANSI A135.4.
g. Alternate fastening is only permitted for roof sheathing where the ultimate design wind speed is less than or equal to 110 mph, and where fasteners are installed 3 inches on
center at all supports, and where fastening is to wood framing of a species with specific gravity greater than or equal to 0.42 in accordance with AWC NDS.
h. Fiber-cement underlayment shall conform to ASTM C1288 or ISO 8336, Category C.|TABLE R602.3(3)—REQUIREMENTS FOR WOOD STRUCTURAL PANEL WALL SHEATHING USED TO RESIST WIND PRESSURESa, b, c Col2 Col3 Col4 Col5 Col6 Col7 Col8 Col9 Col10 ** MINIMUM NAIL** ** MINIMUM NAIL** MINIMUM
WOOD
STRUCTURAL
PANEL SPAN
RATING** MINIMUM**
NOMINAL
PANEL
THICKNESS
(inches)** MAXIMUM**
WALL
STUD
SPACING
(inches)** PANEL**
NAIL SPACING** PANEL**
NAIL SPACING** ULTIMATE DESIGN**
WIND SPEEDVult (mph)** ULTIMATE DESIGN**
WIND SPEEDVult (mph)** ULTIMATE DESIGN**
WIND SPEEDVult (mph)** Size** ** Penetration**
(inches)** Penetration**
(inches)** Penetration**
(inches)** Penetration**
(inches)** Edges**
(inches o.c.)** Field**
(inches o.c.)** Wind exposure category** ** Wind exposure category** ** Wind exposure category** ** Size** ** Penetration**
(inches)** Penetration**
(inches)** Penetration**
(inches)** Penetration**
(inches)** Edges**
(inches o.c.)** Field**
**(inches o.c.CRC § 9-6 High relevance — show source text
A single layer of self-adhering polymer modified bitumen
underlayment complying with ASTM D1970, installed in accor-
dance with the underlayment and roof covering manufacturer’s
installation instructions for the deck material, roof ventilation
configuration and climate exposure of the roof covering.| |Mineral-
surfaced roll
roofing|R905.5|R905.5|R905.5| |Slate and
slate-type
shingles|R905.6|R905.6|R905.6| |Wood shingles|R905.7|R905.7|R905.7| |Wood shakes|R905.8|R905.8|R905.8| |Metal panels|R905.10|R905.10|R905.10|9-6 2025 CALIFORNIA RESIDENTIAL CODE
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
ROOF ASSEMBLIES
TABLE R905.1.1(2)—UNDERLAYMENT APPLICATION—continued Col2 Col3 Col4 ROOF
COVERINGSECTION AREAS WHERE WIND DESIGN IS NOT REQUIRED IN
ACCORDANCE WITH FIGURE R301.2.1.1AREAS WHERE WIND DESIGN IS REQUIRED IN
ACCORDANCE WITH FIGURE R301.2.1.1BIPV roof
coveringsR905.15 Underlayment shall be one of the following:
1. For roof slopes from 2 units vertical in 12 units horizontal
(2:12), up to 4 units vertical in 12 units horizontal (4:12),
underlayment shall be two layers applied in the following
manner: apply a strip of underlayment that is half the width
of a full sheet parallel to and starting at the eaves, fastened
sufficiently to hold in place. Starting at the eave, apply full
width sheets of underlayment, overlapping successive
sheets half the width of a full sheet plus 2 inches. Distortions
in the underlayment shall not interfere with the ability of the
shingles to seal. End laps shall be 4 inches and shall be offset
by 6 feet.
2. For roof slopes of 4 units vertical in 12 units horizontal (4:12)
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. Distortions in the underlayment shall not interfere
with the ability of the shingles to seal. End laps shall be 4
inches and shall be offset by 6 feet.
3. A single layer of self-adhering polymer modified bitumen
underlayment complying with ASTM D1970, installed in
accordance with the underlayment and roof covering manu-
facturer’s installation instructions for the deck material, roof
ventilation configuration and climate exposure of the roof
covering.Underlayment shall be one of the following:
1. Two layers of mechanically fastened underlayment applied in
the following manner: Apply a strip of underlayment that is
half the width of a full sheet parallel to and starting at the
eaves, fastened sufficiently to hold in place.CRC § 4.5 High relevance — show source text
R905.4.5 Application. Metal roof shingles shall be secured to the roof in accordance with this chapter and the approved manufacturer’s installation instructions.
R905.4.6 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 R905.10.3(1). The valley flashing shall extend not less than 8 inches (203 mm) from the centerline each way and shall have a splash diverter rib not less than [3] / 4 inch (19 mm) in height 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). The metal valley flashing shall have a 36inch-wide (914 mm) underlayment directly under it consisting of one layer of underlayment running the full length of the valley, in addition to underlayment required for metal roof shingles. In areas where the average daily temperature in January is 25°F (-4°C) or less, the metal valley flashing underlayment shall be solid-cemented to the roofing underlayment for roof slopes under 7 units vertical in 12 units horizontal (58-percent slope) or self-adhering polymer-modified bitumen sheet.
R905.5 Mineral-surfaced roll roofing. The installation of mineral-surfaced roll roofing shall comply with this section.
R905.5.1 Sheathing requirements. Mineral-surfaced roll roofing shall be fastened to wood structural panels or solid lumber sheathing.
R905.5.2 Slope. Mineral-surfaced roll roofing shall not be applied on roof slopes below 1 unit vertical in 12 units horizontal (8percent slope).
R905.5.3 Underlayment. Underlayment shall comply with Section R905.1.1.
R905.5.3.1 Ice barrier. Where required, ice barriers shall comply with Section R905.1.2.
R905.5.4 Material standards. Mineral-surfaced roll roofing shall conform to ASTM D3909 or ASTM D6380, Class M.
R905.5.5 Application. Mineral-surfaced roll roofing shall be installed in accordance with this chapter and the manufacturer’s instructions.
R905.5.6 Wind resistance of mineral-surfaced roll roofing. Mineral-surfaced roll roofing shall be installed to resist the component and cladding loads specified in Table R301.2.1(1), adjusted for height and exposure in accordance with Table R301.2.1(2).
R905.6 Slate shingles. The installation of slate shingles shall comply with the provisions of this section.
R905.6.1 Sheathing requirements. Slate shingles shall be fastened to wood structural panels or solid lumber sheathing.
R905.6.2 Slope. Slate shingles shall be used only on slopes of 4 units vertical in 12 units horizontal (33-percent slope) or greater.
R905.6.3 Underlayment. Underlayment shall comply with Section R905.1.1.
R905.6.3.1 Ice barrier. Where required, ice barriers shall comply with Section R905.1.2.
R905.6.4 Material standards. Slate shingles shall comply with ASTM C406.
CRC § 3.8. High relevance — show source text
In other areas, clay and concrete roof tiles shall be attached in accordance with Table R905.3.8.
TABLE R905.3.8—CLAY AND CONCRETE TILE ATTACHMENT Col2 Col3 ** SHEATHING** ** ROOF SLOPE** ** NUMBER OF FASTENERS** Solid without battens All One per tile Spaced or solid with battens Slope < 5:12 Fasteners not required Spaced sheathing without battens 5:12 ≤ slope < 12:12 One per tile/every other row Spaced sheathing without battens 12:12 ≤ slope < 24:12 One per tile R905.3.9 Flashing. At the juncture of roof vertical surfaces, flashing and counterflashing shall be provided in accordance with this chapter and the manufacturer’s installation instructions and, where of metal, shall be not less than 0.019 inch (0.5 mm) (No. 26 galvanized sheet gage) corrosion-resistant metal. The valley flashing shall extend not less than 11 inches (279 mm) from the centerline each way and have a splash diverter rib not less than 1 inch (25 mm) in height 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). For roof slopes of 3 units vertical in 12 units horizontal (25-percent slope) and greater, valley flashing shall have a 36-inch-wide (914 mm) underlayment of one layer of Type I underlayment running the full length of the valley, in addition to other required underlayment. In areas where the average daily temperature in January is 25°F (-4°C) or less, metal valley flashing underlayment shall be solid-cemented to the roofing underlayment for slopes less than 7 units vertical in 12 units horizontal (58-percent slope) or be of self-adhering polymer-modified bitumen sheet.
R905.4 Metal roof shingles. The installation of metal roof shingles shall comply with the provisions of this section.
R905.4.1 Sheathing requirements. Metal roof shingles shall be fastened to wood structural panels, solid lumber sheathing or closely fitted lumber sheathing, except where the roof covering is specifically designed to be applied to spaced lumber sheathing.
R905.4.2 Slope. Metal roof shingles shall not be installed on roof slopes below 3 units vertical in 12 units horizontal (25-percent slope).
R905.4.3 Underlayment. Underlayment shall comply with Section R905.1.1.
R905.4.3.1 Ice barrier. Where required, ice barriers shall comply with Section R905.1.2.
R905.4.4 Material standards. Metal roof shingle roof coverings shall comply with Table R905.10.3(1). The materials used for metal roof shingle roof coverings shall be naturally corrosion resistant or be made corrosion resistant in accordance with the standards and minimum thicknesses listed in Table R905.10.3(2).
CRC § 1507.7.8 High relevance — show source text
1507.7.8 Additional requirements. [DSA-SS & DSA-SS/CC, OSHPD 1, 1R, 2, 4 & 5] In addition to the requirements of Section 1507.7.5, the installation of slate shingle roof coverings shall comply with the requirements of Sections 1507.3.6 and 1507.3.7, and the seismic anchorage provisions of Section 1513.
1507.8 Wood shingles. The installation of wood shingles shall comply with the provisions of this section and Table 1507.8.
TABLE 1507.8—WOOD SHINGLE AND SHAKE INSTALLATION Col2 Col3 ROOF ITEM WOOD SHINGLES WOOD SHAKES 1. Roof slope Wood shingles shall be installed on slopes of
not less than 3 units vertical in 12 units hori-
zontal (3:12).Wood shakes shall be installed on slopes of not less
than 4 units vertical in 12 units horizontal (4:12).2. Deck requirement 2. Deck requirement 2. Deck requirement Temperate climate Shingles shall be applied to roofs with solid or
spaced sheathing. Where spaced sheathing is
used, sheathing boards shall be not less than
1″ × 4″ nominal dimensions and shall be
spaced on centers equal to the weather expo-
sure to coincide with the placement of
fasteners.Shakes shall be applied to roofs with solid or spaced
sheathing. Where spaced sheathing is used, sheath-
ing boards shall be not less than 1″ × 4″ nominal
dimensions and shall be spaced on centers equal to
the weather exposure to coincide with the placement
of fasteners. Where 1″ × 4″ spaced sheathing is
installed at 10 inches, boards must be installed
between the sheathing boards.In areas where the average daily
temperature in January is 25°F or
less or where there is a possibility
of ice forming along the eaves
causing a backup of water.Solid sheathing is required. Solid sheathing is required. 3. Interlayment No requirements. Interlayment shall comply with ASTM D226, Type 1. 4. Underlayment 4. Underlayment 4. Underlayment Temperate climate Underlayment shall comply with Section
1507.1.1.Underlayment shall comply with Section 1507.1.1. 5. Application 5. Application 5. Application Attachment Fasteners for wood shingles shall be hot-
dipped galvanized or Type 304 (Type 316 for
coastal areas) stainless steel with a minimum
penetration of 0.75 inch into the sheathing.
For sheathing less than 0.5 inch thick, the
fasteners shall extend through the sheathing.Fasteners for wood shakes shall be hot-dipped galva-
nized or Type 304 (Type 316 for coastal areas) with a
minimum penetration of 0.75 inch into the sheath-
ing. For sheathing less than 0.5 inch thick, the
fasteners shall extend through the sheathing.No. CRC § 1507.3 High relevance — show source text
1507.3 Clay and concrete tile. The installation of clay and concrete tile shall comply with the provisions of this section.
1507.3.1 Deck requirements. Concrete and clay tile shall be installed only over solid sheathing.
Exception: Spaced lumber sheathing shall be permitted in Seismic Design Categories A, B and C. 1507.3.2 Deck slope. Clay and concrete roof tile shall be installed on roof slopes of 2 [1] / 2 units vertical in 12 units horizontal (21percent slope) or greater. For roof slopes from 2 [1] / 2 units vertical in 12 units horizontal (21-percent slope) to 4 units vertical in 12 units horizontal (33-percent slope), double underlayment application is required in accordance with Section 1507.1.1.
1507.3.3 Underlayment. Unless otherwise noted, required underlayment shall conform to: ASTM D226, Type II; ASTM D2626 or ASTM D6380, Class M mineral-surfaced roll roofing.
1507.3.4 Clay tile. Clay roof tile shall comply with ASTM C1167.
1507.3.5 Concrete tile. Concrete roof tile shall comply with ASTM C1492. 1507.3.6 Fasteners. Tile fasteners shall be corrosion resistant and not less than 11-gage, [0.120 inch (3 mm)], [5] / 16 -inch (8.0 mm) head, and of sufficient length to penetrate the deck not less than [3] / 4 inch (19.1 mm) or through the thickness of the deck, which
2025 CALIFORNIA BUILDING CODE 15-11
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
ROOF ASSEMBLIES AND ROOFTOP STRUCTURES
ever 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.
1507.3.7 Attachment. Clay and concrete roof tiles shall be fastened in accordance with Table 1507.3.7.
TABLE 1507.3.7—CLAY AND CONCRETE TILE ATTACHMENTa, b, c Col2 Col3 Col4 Col5 GENERAL—CLAY OR CONCRETE ROOF TILE GENERAL—CLAY OR CONCRETE ROOF TILE GENERAL—CLAY OR CONCRETE ROOF TILE GENERAL—CLAY OR CONCRETE ROOF TILE GENERAL—CLAY OR CONCRETE ROOF TILE Maximum Allow-
able Stress Design
Wind Speed,****Vasd
f
(mph)Mean roof
height (feet)Roof slope < 3:12 Roof slope 3:12 and over Roof slope 3:12 and over 85 0-60 One fastener per tile. Flat tile
without vertical laps, two
fasteners per tile.Two fasteners per tile. Only one fastener on slopes of 7:12 and less
for tiles with installed weight exceeding 7.5 lbs./sq.CRC § 4.1 Medium relevance — show source text
For roof slopes of 3 units vertical in 12 units horizontal (25-percent slope) and greater, valley flashing shall have a 36-inch-wide (914 mm) underlayment of one layer of Type I underlayment running the full length of the valley, in addition to other required underlayment. In areas where the average daily temperature in January is 25°F (-4°C) or less, metal valley flashing underlayment shall be solid-cemented to the roofing underlayment for slopes less than 7 units vertical in 12 units horizontal (58-percent slope) or be of self-adhering polymer-modified bitumen sheet.
R905.4 Metal roof shingles. The installation of metal roof shingles shall comply with the provisions of this section.
R905.4.1 Sheathing requirements. Metal roof shingles shall be fastened to wood structural panels, solid lumber sheathing or closely fitted lumber sheathing, except where the roof covering is specifically designed to be applied to spaced lumber sheathing.
R905.4.2 Slope. Metal roof shingles shall not be installed on roof slopes below 3 units vertical in 12 units horizontal (25-percent slope).
R905.4.3 Underlayment. Underlayment shall comply with Section R905.1.1.
R905.4.3.1 Ice barrier. Where required, ice barriers shall comply with Section R905.1.2.
R905.4.4 Material standards. Metal roof shingle roof coverings shall comply with Table R905.10.3(1). The materials used for metal roof shingle roof coverings shall be naturally corrosion resistant or be made corrosion resistant in accordance with the standards and minimum thicknesses listed in Table R905.10.3(2).
R905.4.4.1 Wind resistance of metal roof shingles. Metal roof shingles fastened to wood structural panels, solid lumber sheathing or closely fitted lumber sheathing shall be tested in accordance with ASTM D3161, FM 4474, UL 580 or UL 1897. Metal roof shingles tested in accordance with ASTM D3161 shall meet the classification requirements of Table R905.4.4.1 for the appropriate maximum basic wind speed and the metal shingle packaging shall bear a label to indicate compliance with ASTM D3161 and the required classification in Table R905.2.4.1.
9-10 2025 CALIFORNIA RESIDENTIAL CODE
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
ROOF ASSEMBLIES
CRC § 0.097 Medium relevance — show source text
roofg and wall sheathing to framing and particleboard wall sheathing to framingf**| |Up to1/2|Staple 15 ga. 13/4|4|8| |Up to1/2|0.097–0.099 Nail 21/4|3|6| |Up to1/2|Staple 16 ga. 13/4|3|6| |19/32 and5/8|0.113 Nail 2|3|6| |19/32 and5/8|Staple 15 and 16 ga. 2|4|8| |19/32 and5/8|0.097–0.099 Nail 21/4|4|8| |23/32 and3/4|Staple 14 ga. 2|4|8| |23/32 and3/4|Staple 15 ga. 13/4|3|6| |23/32 and3/4|0.097–0.099 Nail 21/4|4|8| |23/32 and3/4|Staple 16 ga. 2|4|8| |1|Staple 14 ga. 21/4|4|8| |1|0.113 Nail 21/4|3|6| |1|Staple 15 ga. 21/4|4|8| |1|0.097–0.099 Nail 21/2|4|8|
2025 CALIFORNIA RESIDENTIAL CODE 6-7
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
WALL CONSTRUCTION
TABLE R602.3(2)—ALTERNATE ATTACHMENTS TO TABLE R602.3(1)—continued Col2 Col3 Col4 NOMINAL MATE-
RIAL THICKNESS
(inches)DESCRIPTIONa, b OF FASTENER AND LENGTH
(inches)SPACINGc OF FASTENERS SPACINGc OF FASTENERS NOMINAL MATE-
RIAL THICKNESS
(inches)DESCRIPTIONa, b OF FASTENER AND LENGTH
(inches)Edges
(inches)Body of paneld
(inches)Floor underlayment; plywood-hardboard-particleboardf-fiber-cementh Floor underlayment; plywood-hardboard-particleboardf-fiber-cementh Floor underlayment; plywood-hardboard-particleboardf-fiber-cementh Floor underlayment; plywood-hardboard-particleboardf-fiber-cementh Fiber-cement Fiber-cement Fiber-cement Fiber-cement 1/4 11/4 long × 0.099″ corrosion-resistant, ring shank nails (finished flooring other than tile) 3 6 1/4 Staple 18 ga.7/8 long,1/4 crown (finished flooring other than tile) 3 6 1/4 11/4 long × .121 shank × .375 head diameter corrosion-resistant
(galvanized or stainless steel) roofing nails (for tile finish)8 8 1/4 11/4 long, No.
Frequently asked questions
Do roof coverings always need an ice barrier or double underlayment?
Ice barriers and double underlayment are required where specified by §R905.1.2 and by the roof‑covering sections based on climate and slope (for example double underlayment for certain slopes of asphalt and tile and ice‑barrier areas identified in Table R301.2); the CRC spells out where an ice barrier or two layers of underlayment are mandatory.
Where do I find the required nail/staple type and spacing for sheathing?
Sheathing fastener type, minimum penetration and edge/field spacing are given in the sheathing attachment schedules (Table R602.3(2) and related tables). Those tables list allowable nails/staples, required penetration and common spacings (for example 6" or 12" o.c. and 4" o.c. at edges in some wind exposures).
Can self‑adhering underlayment be used everywhere?
Self‑adhering polymer‑modified bitumen underlayment complying with ASTM D1970 is permitted in many applications and is often specified as an acceptable single‑layer option, but the code and the roof‑covering sections include exceptions (for example it is not permitted under wood shakes/shingles) and require installation in accordance with manufacturer instructions and the applicable section (§R905.1.1 and related roof sections).
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