CBC · California Building Code
What are the CBC installation standards for asphalt, slate, metal and single-ply roofs?
For homeowners: the CBC requires asphalt shingles only on solid decks with minimum slopes and underlayment rules, slate and metal roofing on solid sheathing and tested/labeled materials, and single‑ply membranes to meet minimum slope and ASTM standards; follow the specific section cited for each product (see §§ 1507.2, 1507.4, 1507.7, 1507.12).
Last reviewed: July 5, 2026
What the code requires
The California Building Code (CBC) sets prescriptive installation limits and material standards for common roof coverings. For asphalt shingles the CBC requires installation on solid sheathing, a minimum slope and specified underlayment treatments (§ 1507.2). Metal roof panels are installed per the manufacturer’s instructions with underlayment and wind-resistance testing requirements (§ 1507.4). Slate must be fastened to solid sheathing and meet required test/labeling standards (§ 1507.7). Single‑ply membranes have minimum slope, required ASTM material standards and special rules for ballasted low‑slope systems (§ 1507.12).
Requirements in detail
Asphalt shingles (controlling section § 1507.2)
- Deck: Asphalt shingles must be fastened to solidly sheathed decks (§ 1507.2.1).
- Slope: Asphalt shingles are permitted only on slopes ≥ 2 units vertical in 12 units horizontal (2:12 = 17%); for slopes from 2:12 up to 4:12 a double underlayment application is required (§ 1507.2.2).
- Material standard: Asphalt shingles must comply with ASTM D3462 (and wind classification/testing per ASTM D7158 or ASTM D3161 where applicable) (§ 1504.2 and § 1507.2.4).
Metal roof panels (controlling section § 1507.4)
- Installation basis: Metal roof panels are to be installed in accordance with the manufacturer’s installation instructions; underlayment and fasteners must comply with the underlayment section (§ 1507.4 and § 1507.4.5).
- Deck: Many metal panel systems require a solid or closely fitted roof deck; structural metal panel systems have separate testing/structural requirements (§ 1504.4.2).
- Wind/Testing: Metal panel systems applied to a solid deck must be tested in accordance with FM 4474, UL 580 or UL 1897 (and structural systems per ASTM E1592 where applicable) (§ 1504.4.1–.2).
- Underlayment fastening details: Where mechanically fastened underlayment is used the CBC specifies corrosion‑resistant fasteners and gives grid/lap spacing requirements for the fasteners and caps (see underlayment rules) (§ 1507.1.1 / § 1507.4.5).
Slate shingles (controlling section § 1507.7)
- Deck: Slate must be fastened to solidly sheathed roofs (§ 1507.7.1).
- Testing/labeling: Slate shingles must be tested and labeled in accordance with ASTM D3161 and meet the wind classification requirements in Table 1504.2 (see wind‑resistance/testing provisions) (§ 1504.4.4).
- Underlayment/ice barrier: Underlayment requirements and ice barriers where applicable apply to slate the same as other coverings per § 1507.1.2.
Single‑ply membrane (controlling section § 1507.12)
- Slope: Single‑ply membranes must have a design slope of not less than 1/4 unit vertical in 12 units horizontal (0.25:12 = 2% slope) (§ 1507.12.1).
- Material standards: Single‑ply roofing must comply with the material standards listed in Table 1507.12.2 (EPDM ASTM D4637; PVC ASTM D4434; TPO ASTM D6878; etc.) (§ 1507.12.2).
- Ballasted systems: Ballasted low‑slope single‑ply roofs have separate installation/design rules and must comply with ANSI/SPRI RP‑4 and Section 1504.5 (§ 1507.12.3).
Quick reference table (decision‑relevant numbers and values)
| Topic | Value / Requirement | Code Reference |
|---|---|---|
| Asphalt shingle minimum slope | 2 units vertical in 12 horizontal (2:12) | § 1507.2 |
| Double underlayment required | Roof slope ≥ 2:12 and < 4:12 | § 1507.2.2 |
| Single‑ply minimum slope | 1/4 unit vertical in 12 horizontal (2% = 0.25:12) | § 1507.12.1 |
| Slate / metal shingle deck | Solidly sheathed decks required | § 1507.7.1; § 1507.5.1 |
| Ice barrier extent | From lowest roof edge to not less than 24 in inside exterior wall line (36 in on slopes ≥ 8:12) | § 1507.1.2 |
| Metal valley flashing (metal shingles) | Extend ≥ 8 in from centerline each way; 36‑in underlayment in cold/ice areas | § 1507.5.7 |
| Single‑ply material standards | EPDM (ASTM D4637), PVC (ASTM D4434), TPO (ASTM D6878), etc. | Table 1507.12.2 (§ 1507.12.2) |
| Wind/testing for membrane/metal | FM 4474, UL 580 or UL 1897; structural metal per ASTM E1592 | § 1504.4.1–.2 |
Exceptions & special cases
- Ice‑barrier exception: Detached accessory structures without conditioned floor area are exempt from the ice‑barrier requirement (§ 1507.1.2).
- Manufacturer instructions: For many metal panel systems and single‑ply membranes the CBC defers to the manufacturer’s specific installation instructions; the code requires that those instructions be followed and that systems meet the material and testing standards (§ 1507.4; § 1507.12).
- Recover vs. tear‑off: The residential code (R908) contains additional rules when installing a new roof over old roof coverings — some coverings (for example, slate, clay, cement tile) often require tear‑off rather than recover. These reroofing/recover limits are state residential provisions and must be checked in reroof scenarios.
If you need a code requirement not shown above (for example very detailed fastening schedules for a specific metal panel profile), the retrieved CBC excerpts do not include every manufacturer‑specific fastening table — in such cases the code directs you to the manufacturer’s installation instructions and to the testing/labeling requirements cited above (§ 1507.4; § 1504.4).
Common mistakes
- Applying asphalt shingles on spaced sheathing or open decking — asphalt shingles must be on solid sheathing (§ 1507.2.1).
- Missing double underlayment on slopes between 2:12 and 4:12. Inspectors commonly see single underlayment where CBC requires two layers (§ 1507.2.2).
- Assuming all metal panels are interchangeable — some metal panels are structural and require ASTM E1592 testing, others are non‑structural; follow the manufacturer's tested system and CBC testing references (§ 1504.4.2).
- Forgetting ice‑barrier in cold/ice‑prone eave areas or not extending it the full 24 in (or 36 in on steep slopes) (§ 1507.1.2).
- Installing single‑ply membrane below the 2% minimum slope or using an unlisted membrane that does not meet the ASTM standards in Table 1507.12.2 (§ 1507.12.1–.2).
Worked example
Scenario: You are replacing a roof on a house in the Sierra foothills (ice‑prone eaves) with new asphalt shingles. Roof pitch = 3 in 12; slope across a valley also exists.
Steps (CBC‑grounded):
- Slope check: 3:12 is ≥ 2:12 and < 4:12, so asphalt shingles are permitted but require a double underlayment application per § 1507.2.2.
- Deck: Ensure the roof deck is solidly sheathed before fastening shingles (§ 1507.2.1).
- Ice barrier: Because the location is ice‑prone, install an ice barrier that extends from the eave up to at least 24 inches inside the exterior wall line (CBC ice‑barrier rule) (§ 1507.1.2). If any portion of the roof has slope ≥ 8:12 apply the 36‑inch rule where applicable (§ 1507.1.2).
- Material labeling/wind: Use asphalt shingles that are labeled to show compliance with ASTM D7158 (or ASTM D3161 where applicable) and the required wind classification per the local basic wind speed table (Table 1504.2) (§ 1504.2 / § 1507.2.4).
- Flashing and valleys: Provide code‑required valley and flashing per § 1503.2 and the asphalt shingle provisions; in cold areas consider additional underlayment under valley flashings (see metal shingle guidance for valley extents where similar rules apply).
Related provisions (useful cross‑references)
- Ice barriers and underlayment rules — § 1507.1.2.
- Wind resistance/testing of roof coverings — § 1504.1 and § 1504.4.
- Metal roof panels testing/structural standards — § 1504.4.1–.2.
- Metal roof shingles — § 1507.5.
- Valley and flashing requirements — § 1503.2 and the individual covering sections (e.g., § 1507.5.7 for valley flashing specifics).
- Single‑ply material standards and ballasted systems — § 1507.12 (Table 1507.12.2 and § 1507.12.3).
Code references
Grounded in the retrieved California Building Code — click a citation to read the verbatim passage:
CBC § 1507.11 High relevance — show source text
Type I or II| |Coal-tar primer used in roofing, dampproofing and waterproofing|ASTM D43| |Glass mat, coal-tar|ASTM D4990| |Glass mat, venting type|ASTM D4897| |Mineral-surfaced inorganic cap sheet|ASTM D3909| |Thermoplastic fabrics used in roofing|ASTM D5665, D5726|
1507.11 Modified bitumen roofing. The installation of modified bitumen roofing shall comply with the provisions of this section. 1507.11.1 Slope. Modified bitumen roofing shall have a design slope of not less than [1] / 4 unit vertical in 12 units horizontal (2percent slope) for drainage.
1507.11.2 Material standards. Modified bitumen roofing materials shall comply with ASTM D6162, ASTM D6163, ASTM D6164, ASTM D6222, ASTM D6223, ASTM D6298 or ASTM D6509.
1507.11.2.1 Base sheet. A base sheet that complies with the requirements of Section 1507.11.2, ASTM D1970 or ASTM D4601 shall be permitted to be used with a modified bitumen cap sheet.
1507.12 Single-ply roofing. The installation of single-ply roofing shall comply with the provisions of this section. 1507.12.1 Slope. Single-ply membrane roofs shall have a design slope of not less than [1] / 4 unit vertical in 12 units horizontal (2-percent slope) for drainage.
1507.12.2 Material standards. Single-ply roof coverings shall comply with the material standards in Table 1507.12.2.
TABLE 1507.12.2—SINGLE-PLY ROOFING MATERIAL STANDARDS Col2 MATERIAL MATERIAL STANDARD Chlorosulfonated polyethylene (CSPE) or polyisobutylene (PIB) ASTM D5019 Ethylene propylene diene monomer (EPDM) ASTM D4637 Ketone Ethylene Ester (KEE) ASTM D6754 Polyvinyl Chloride (PVC) or (PVC/KEE) ASTM D4434 Thermoplastic polyolefin (TPO) ASTM D6878 15-18 2025 CALIFORNIA BUILDING CODE
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1507.12.3 Ballasted low-slope roofs. Ballasted low-slope roofs shall be installed in accordance with this section and Section 1504.5. Stone used as ballast shall comply with ASTM D448 or ASTM D7655.
1507.13 Sprayed polyurethane foam roofing. The installation of sprayed polyurethane foam roofing shall comply with the provisions of this section.
1507.13.1 Slope. Sprayed polyurethane foam roofs shall have a design slope of not less than [1] / 4 unit vertical in 12 units horizontal (2-percent slope) for drainage.
1507.13.2 Material standards. Spray-applied polyurethane foam insulation shall comply with ASTM C1029 Type III or IV or ASTM D7425.
CBC § 1507.10.2 High relevance — show source text
1507.10.2 Material standards. Built-up roof covering materials shall comply with the standards in Table 1507.10.2 or UL 55A.
TABLE 1507.10.2—BUILT-UP ROOFING MATERIAL STANDARDS Col2 MATERIAL STANDARD STANDARD Acrylic coatings used in roofing ASTM D6083 Aggregate surfacing ASTM D1863 Asphalt adhesive used in roofing ASTM D3747 Asphalt cements used in roofing ASTM D2822; D3019; D4586 Asphalt-coated glass fiber base sheet ASTM D4601 Asphalt coatings used in roofing ASTM D1227; D2823; D2824; D4479 Asphalt glass felt ASTM D2178 Asphalt primer used in roofing ASTM D41 Asphalt-saturated and asphalt-coated organic felt base sheet ASTM D2626 Asphalt-saturated organic felt (perforated) ASTM D226 Asphalt used in roofing ASTM D312 Coal-tar cements used in roofing ASTM D4022; D5643 Coal-tar saturated organic felt ASTM D227 Coal-tar pitch used in roofing ASTM D450; Type I or II Coal-tar primer used in roofing, dampproofing and waterproofing ASTM D43 Glass mat, coal-tar ASTM D4990 Glass mat, venting type ASTM D4897 Mineral-surfaced inorganic cap sheet ASTM D3909 Thermoplastic fabrics used in roofing ASTM D5665, D5726 1507.11 Modified bitumen roofing. The installation of modified bitumen roofing shall comply with the provisions of this section. 1507.11.1 Slope. Modified bitumen roofing shall have a design slope of not less than [1] / 4 unit vertical in 12 units horizontal (2percent slope) for drainage.
1507.11.2 Material standards. Modified bitumen roofing materials shall comply with ASTM D6162, ASTM D6163, ASTM D6164, ASTM D6222, ASTM D6223, ASTM D6298 or ASTM D6509.
1507.11.2.1 Base sheet. A base sheet that complies with the requirements of Section 1507.11.2, ASTM D1970 or ASTM D4601 shall be permitted to be used with a modified bitumen cap sheet.
1507.12 Single-ply roofing. The installation of single-ply roofing shall comply with the provisions of this section. 1507.12.1 Slope. Single-ply membrane roofs shall have a design slope of not less than [1] / 4 unit vertical in 12 units horizontal (2-percent slope) for drainage.
1507.12.2 Material standards. Single-ply roof coverings shall comply with the material standards in Table 1507.12.2.
CBC § 9-16 High relevance — show source text
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TABLE R905.11.2—MODIFIED BITUMEN ROOFING MATERIAL STANDARDS Col2 ** MATERIAL** ** STANDARD** Acrylic coating ASTM D6083 Asphalt adhesive ASTM D3747 Asphalt cement ASTM D3019 Asphalt coating ASTM D1227; D2824 Asphalt primer ASTM D41 Modified bitumen roof membrane ASTM D6162; D6163; D6164; D6222; D6223; D6298 R905.11.2.1 Base sheet. A base sheet that complies with the requirements of Section 1507.11.2 of the California Building Code, ASTM D1970 or ASTM D4601 shall be permitted to be used with a modified bitumen cap sheet.
R905.11.3 Application. Modified bitumen roofs shall be installed in accordance with this chapter and the manufacturer’s instructions.
R905.11.4 Wind resistance of modified bitumen roofing. Modified bitumen roofing shall be tested in accordance with FM 4474, UL 580 or UL 1897 and 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).
R905.12 Single-ply roofing. The installation of single-ply membrane roof coverings shall comply with the provisions of this section.
TABLE R905.12—SINGLE-PLY ROOFING MATERIAL STANDARDS Col2 MATERIAL STANDARD Chlorosulfanated polyethylene (CSPE) or polyisobutylene (PIB) ASTM D5019 Ethylene propylene diene monomer (EPDM) ASTM D4637 Ketone Ethylene Ester (KEE) ASTM D6754 Polyvinyl chloride (PVC) or (PVC/KEE) ASTM D4434 Thermosplastic polyolefin (TPO) ASTM D6878 R905.12.1 Slope. Single-ply membrane roof coverings shall have a design slope of not less than [1] / 4 unit vertical in 12 units horizontal (2-percent slope) for drainage.
R905.12.2 Material standards. Single-ply membrane roof coverings shall comply with the material standards in Table R905.12.
R905.12.3 Application. Single-ply membrane roof coverings shall be installed in accordance with this chapter and the manufacturer’s installation instructions.
R905.12.4 Wind resistance of single-ply roofing. Single-ply roofing shall be tested in accordance with FM 4474, UL 580 or UL 1897 and 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).
R905.13 Sprayed polyurethane foam roofing. The installation of sprayed polyurethane foam roofing shall comply with the provisions of this section.
CBC § 1504.3.1.3 High relevance — show source text
1504.3.1.3 Air permeability testing. The lift coefficient for concrete and clay tile shall be 0.2 or shall be determined in accordance with SBCCI SSTD 11 or ASTM C1570.
1504.4 Wind resistance of nonballasted roofs. Roof coverings installed on roofs in accordance with Section 1507 that are mechanically attached or adhered to the roof deck shall be designed to resist the design wind load pressures for components and cladding in accordance with Section 1609.6.2. The wind load on the roof covering shall be permitted to be determined using allowable stress design.
1504.4.1 Other roof systems. Built-up, modified bitumen, fully adhered or mechanically attached single-ply roof systems, metal panel roof systems applied to a solid or closely fitted deck and other types of membrane roof coverings shall be tested in accordance with FM 4474, UL 580 or UL 1897.
1504.4.2 Structural metal panel roof systems. Where the metal roof panel functions as the roof deck and roof covering and it provides both weather protection and support for loads, the structural metal panel roof system shall comply with this section. Structural standing-seam metal panel roof systems shall be tested in accordance with ASTM E1592 or FM 4474. Structural through-fastened metal panel roof systems shall be tested in accordance with ASTM E1592, FM 4474 or UL 580.
Exceptions:
- Metal roofs constructed of cold-formed steel shall be permitted to be designed and tested in accordance with the applicable referenced structural design standard in Section 2204.1.
- Metal roofs constructed of aluminum shall be permitted to be designed and tested in accordance with the applicable referenced structural design standard in Section 2002.1.
1504.4.3 Metal roof shingles. Metal roof shingles applied to a solid or closely fitted deck 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 1504.2 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 1504.2.
1504.4.4 Slate shingles. Slate shingles shall be tested in accordance with ASTM D3161. Slate packaging shall bear a label indicating compliance with ASTM D3161 and the required classification in Table 1504.2.
1504.5 Ballasted low-slope single-ply roof systems. Ballasted low-slope single-ply roof system coverings installed in accordance with Section 1507.12 shall be designed in accordance with ANSI/SPRI RP-4.
1504.6 Edge systems for low-slope roofs. Metal edge systems, except gutters and counterflashing, installed on built-up, modified bitumen and single-ply roof systems on a low-slope roof shall be designed and installed for wind loads in accordance with Chapter 16
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and tested for resistance in accordance with Test Methods RE-1, RE-2 and RE-3 of ANSI/SPRI ES-1, except basic wind speed, V, shall be determined from Figures 1609.3(1)through 1609.3(4), as applicable.
CBC § 25.4 High relevance — show source text
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.
Self-adhering polymer modified bitumen underlayment
shall be 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.
Exception: Self-adhering polymer modified bitumen under-
layment shall not be installed under wood shakes or wood
shingles.| |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| |For SI: 1 inch = 25.4 mm, 1 mile per hour = 0.447 m/s.|For SI: 1 inch = 25.4 mm, 1 mile per hour = 0.447 m/s.|For SI: 1 inch = 25.4 mm, 1 mile per hour = 0.447 m/s.|For SI: 1 inch = 25.4 mm, 1 mile per hour = 0.447 m/s.|2025 CALIFORNIA RESIDENTIAL CODE 9-7
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R905.1.2 Ice barriers. In areas where there has been a history of ice forming along the eaves causing a backup of water as designated in Table R301.2, an ice barrier shall be installed for asphalt shingles, metal roof shingles, mineral-surfaced roll roofing, slate and slate-type shingles, wood shingles and wood shakes. The ice barrier shall consist of not fewer than two layers of underlayment cemented together, or a self-adhering polymer-modified bitumen sheet shall be used in place of normal underlayment and extend from the lowest edges of all roof surfaces to a point not less than 24 inches (610 mm) inside the exterior wall line of the building.
On roofs with slope equal to or greater than 8 units vertical in 12 units horizontal (67-percent slope), the ice barrier shall be applied not less than 36 inches (914 mm) measured along the roof slope from the eave edge of the building.
Exception: Detached accessory structures not containing conditioned floor area.
R905.2 Asphalt shingles. The installation of asphalt shingles shall comply with the provisions of this section.
R905.2.1 Sheathing requirements. Asphalt shingles shall be fastened to wood structural panels or solid lumber sheathing.
R905.2.2 Slope. Asphalt shingles shall be used only on roof slopes of 2 units vertical in 12 units horizontal (17-percent slope) or greater. For roof slopes from 2 units vertical in 12 units horizontal (17-percent slope) up to 4 units vertical in 12 units horizontal (33-percent slope), double underlayment application is required in accordance with Section R905.1.1.
R905.2.3 Underlayment. Underlayment shall comply with Section R905.1.1.
CBC § 3.1. High relevance — show source text
- Where the existing roof includes one layer of self-adhered underlayment and the existing layer cannot be removed without damaging the roof deck, a second layer of self-adhered underlayment is permitted to be installed over the existing self-adhered underlayment provided that the following conditions are met: 3.1. It is permitted by the roof covering manufacturer and new self-adhered underlayment manufacturer. 3.2. The existing sheathing is not water soaked or deteriorated to the point that it is not adequate as a base for additional roofing. 3.3. The second layer of self-adhered underlayment is installed such that buildup of material at walls, valleys, roof edges, end laps, and side laps does not exceed two layers.
R908.4 Roof recover. The installation of a new roof covering over an existing roof covering shall be permitted where any of the following conditions occur:
- Where the new roof covering is installed in accordance with the roof covering manufacturer’s approved instructions.
- Complete and separate roofing systems, such as standing-seam metal roof systems, that are designed to transmit the roof loads directly to the building’s structural system and do not rely on existing roofs and roof coverings for support, shall not require the removal of existing roof coverings.
- Metal panel, metal shingle and concrete and clay tile roof coverings shall be permitted to be installed over existing wood shake roofs where applied in accordance with Section R908.4.1.
- The application of a new protective roof coating over an existing protective roof coating, metal roof panel, metal roof shingle, mineral surfaced roll roofing, built-up roof, modified bitumen roofing, thermoset and thermoplastic single-ply roofing and spray polyurethane foam roofing system shall be permitted without tear-off of existing roof coverings.
Exceptions: A roof recover shall not be permitted where any of the following conditions occur:
- Where the existing roof or roof covering is water soaked or has deteriorated to the point that the existing roof or roof covering is not adequate as a base for the additional roofing.
- Where the existing roof covering is slate, clay, cement or asbestos-cement title.
- Where the existing roof has two or more applications of any type of roof covering.
R908.4.1 Roof recovering over wood shingles or shakes. Where the application of a new roof covering over wood shingle or shake roofs creates a combustible concealed space, the entire existing surface shall be covered with gypsum board, mineral fiber, glass fiber or other approved materials securely fastened in place.
R908.5 Reinstallation of materials. Existing slate, clay or cement tile shall be permitted for reinstallation, except that damaged, cracked or broken slate or tile shall not be reinstalled. Any existing flashings, edgings, outlets, vents or similar devices that are a part of the assembly shall be replaced where rusted, damaged or deteriorated. Aggregate surfacing materials shall not be reinstalled.
R908.6 Flashings. Flashings shall be reconstructed in accordance with approved manufacturer’s installation instructions. Metal flashing to which bituminous materials are to be adhered shall be primed prior to installation.
SECTION R909—ROOF COATINGS
R909.1 General. The installation of a roof coating on a roof covering shall comply with the requirements of Section R902, Section R904 and this section. Roof coatings shall be installed in accordance with the manufacturer’s installation instructions.
R909.2 Material standards. Roof coating materials shall comply with one of the standards in Table R909.2.
CBC § 1504.4.4 High relevance — show source text
1504.4.4 Slate shingles. Slate shingles shall be tested in accordance with ASTM D3161. Slate packaging shall bear a label indicating compliance with ASTM D3161 and the required classification in Table 1504.2.
1504.5 Ballasted low-slope single-ply roof systems. Ballasted low-slope single-ply roof system coverings installed in accordance with Section 1507.12 shall be designed in accordance with ANSI/SPRI RP-4.
1504.6 Edge systems for low-slope roofs. Metal edge systems, except gutters and counterflashing, installed on built-up, modified bitumen and single-ply roof systems on a low-slope roof shall be designed and installed for wind loads in accordance with Chapter 16
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and tested for resistance in accordance with Test Methods RE-1, RE-2 and RE-3 of ANSI/SPRI ES-1, except basic wind speed, V, shall be determined from Figures 1609.3(1)through 1609.3(4), as applicable.
1504.6.1 Gutter securement for low-slope roofs. Gutters that are used to secure the perimeter edge of the roof membrane on low-slope built-up, modified bitumen, and single-ply roofs, shall be designed, constructed and installed to resist wind loads in accordance with Section 1609 and shall be tested in accordance with Test Methods G-1 and G-2 of SPRI GT-1.
1504.7 Impact resistance. Roof coverings installed on low-slope roofs in accordance with Section 1507 shall resist impact damage based on the results of tests conducted in accordance with ASTM D3746, ASTM D4272 or the “Resistance to Foot Traffic Test” in FM 4470.
1504.8 Wind resistance of aggregate-surfaced roofs. Parapets shall be provided for aggregate surfaced roofs and shall comply with Table 1504.8. Such parapets shall be provided on the perimeter of the roof at all exterior sides except where an adjacent wall extends above the roof to a height at least equivalent to that required for the parapet. For roofs with differing surface elevations due to slope or sections at different elevations, the minimum parapet height shall be determined based on each roof surface elevation, and at no point shall the parapet height be less than that required by Table 1504.8.
Exception: Ballasted single-ply roof coverings shall be designed and installed in accordance with Section 1504.5.
|TABLE 1504.8—MINIMUM REQUIRED PARAPET HEIGHT (INCHES) FOR AGGREGATE SURFACED ROOFSa, b, c, d,
CBC § 4.1 High relevance — show source text
1|||X||||||||||||||||||||| |R902.1 - R902.4|||X||||||||||||||||||||| |R903.4.1||||X|||||||||||||||||||| |R904.1 - R904.4|||X||||||||||||||||||||| |R905.15||||X|||||||||||||||||||| |R905.16||||X|||||||||||||||||||| |R907.1||||X|||||||||||||||||||| |R907.2 – R907.5|||X||||||||||||||||||||| |R909|||X|||||||||||||||||||||
The state agency does not adopt sections identified with the following symbol: †
2025 CALIFORNIA RESIDENTIAL CODE 9-1
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9-2 2025 CALIFORNIA RESIDENTIAL CODE
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9 ROOF ASSEMBLIES
User notes:
About this chapter: Chapter 9 addresses the design and construction of roof assemblies. A roof assembly includes the roof deck, substrate or thermal barrier, insulation, vapor retarder and roof covering. This chapter provides the requirement for wind resistance of roof coverings. The types of roof covering materials and installation addressed by Chapter 9 are: asphalt shingles, clay and concrete tile, metal roof shingles, mineral-surfaced roll roofing, slate and slate-type shingles, wood shakes and shingles, built-up roofs, metal roof panels, modified bitumen roofing, thermoset and thermoplastic single-ply roofing, sprayed polyurethane foam roofing, liquid applied coatings and building-integrated photovoltaic (BIPV) roof coverings. Chapter 9 also provides requirements for roof drainage, flashing, above-deck thermal insulation, rooftop-mounted photovoltaic systems and recovering or replacing an existing roof covering.
SECTION R901—GENERAL
R901.1 Scope. The provisions of this chapter shall govern the design, materials, construction and quality of roof assemblies.
SECTION R902—FIRE CLASSIFICATION
R902.1 Roof assemblies. Roof decks shall be covered with materials as set forth in Section R904 or with roof coverings as set forth in Section R905. A minimum Class A, B or C roofing shall be installed in areas designated by this section or where the edge of the roof deck is less than 3 feet (914 mm) from a lot line. Where Class A, B or C roof assemblies are required, they shall be tested in accordance with ASTM E108 or UL 790. Where required, the roof assembly shall be listed and identified as to class by an approved testing agency.
Exceptions:
Class A roof assemblies include those with coverings of brick, masonry and exposed concrete roof deck.
Class A roof assemblies include ferrous or copper shingles or sheets, metal sheets and shingles, clay or concrete roof tile, or slate installed on noncombustible roof decks or ferrous, copper or metal sheets installed without a roof deck on noncombustible framing.
Class A roof assemblies include minimum 16 ounces per square foot (4.882 kg/m [2] ) copper sheets installed over combustible roof decks.
Class A roof assemblies include slate installed over underlayment over ASTM D226, Type II underlayment over combustible decks.
CBC § 10.5 High relevance — show source text
R905.10.5 Wind resistance of metal roof panels. Metal roof panels 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). Metal roof panels applied to a solid or closely fitted deck shall be tested for wind resistance in accordance with FM 4474, UL 580, or UL 1897. Structural standing seam metal panel roof systems shall be tested for wind resistance in accordance with ASTM E1592 or FM 4474. Structural through-fastened metal panel roof systems shall be tested for wind resistance in accordance with ASTM E1592, FM 4474 or UL 580.
Exceptions:
- Metal roofs constructed of cold-formed steel shall be permitted to be designed and tested in accordance with the applicable referenced structural design standard in Section 2208.1 of the California Building Code .
- Metal roofs constructed of aluminum shall be permitted to be designed and tested in accordance with the applicable referenced structural design standard in Section 2002.1 of the California Building Code .
R905.10.6 Underlayment. Underlayment shall comply with Section R905.1.1.
R905.11 Modified bitumen roofing. The installation of modified bitumen roofing shall comply with the provisions of this section and the manufacturer’s approved installation instructions.
R905.11.1 Slope. Modified bitumen roofing shall have a design slope of not less than one-fourth unit vertical in 12 units horizontal (2-percent slope) for drainage.
R905.11.2 Material standards. Modified bitumen roofing shall comply with the standards in Table R905.11.2.
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ROOF ASSEMBLIES
TABLE R905.11.2—MODIFIED BITUMEN ROOFING MATERIAL STANDARDS Col2 ** MATERIAL** ** STANDARD** Acrylic coating ASTM D6083 Asphalt adhesive ASTM D3747 Asphalt cement ASTM D3019 Asphalt coating ASTM D1227; D2824 Asphalt primer ASTM D41 Modified bitumen roof membrane ASTM D6162; D6163; D6164; D6222; D6223; D6298 R905.11.2.1 Base sheet. A base sheet that complies with the requirements of Section 1507.11.2 of the California Building Code, ASTM D1970 or ASTM D4601 shall be permitted to be used with a modified bitumen cap sheet.
R905.11.3 Application. Modified bitumen roofs shall be installed in accordance with this chapter and the manufacturer’s instructions.
R905.11.4 Wind resistance of modified bitumen roofing. Modified bitumen roofing shall be tested in accordance with FM 4474, UL 580 or UL 1897 and 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).
R905.12 Single-ply roofing. The installation of single-ply membrane roof coverings shall comply with the provisions of this section.
CBC § 1507.12.2 High relevance — show source text
TABLE 1507.12.2—SINGLE-PLY ROOFING MATERIAL STANDARDS Col2 MATERIAL MATERIAL STANDARD Chlorosulfonated polyethylene (CSPE) or polyisobutylene (PIB) ASTM D5019 Ethylene propylene diene monomer (EPDM) ASTM D4637 Ketone Ethylene Ester (KEE) ASTM D6754 Polyvinyl Chloride (PVC) or (PVC/KEE) ASTM D4434 Thermoplastic polyolefin (TPO) ASTM D6878 15-18 2025 CALIFORNIA BUILDING CODE
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ROOF ASSEMBLIES AND ROOFTOP STRUCTURES
1507.12.3 Ballasted low-slope roofs. Ballasted low-slope roofs shall be installed in accordance with this section and Section 1504.5. Stone used as ballast shall comply with ASTM D448 or ASTM D7655.
1507.13 Sprayed polyurethane foam roofing. The installation of sprayed polyurethane foam roofing shall comply with the provisions of this section.
1507.13.1 Slope. Sprayed polyurethane foam roofs shall have a design slope of not less than [1] / 4 unit vertical in 12 units horizontal (2-percent slope) for drainage.
1507.13.2 Material standards. Spray-applied polyurethane foam insulation shall comply with ASTM C1029 Type III or IV or ASTM D7425.
1507.13.3 Application. Foamed-in-place roof insulation shall be installed in accordance with the manufacturer’s instructions. A liquid-applied protective coating that complies with Table 1507.13.3 shall be applied not less than 2 hours nor more than 72 hours following the application of the foam.
TABLE 1507.13.3—PROTECTIVE COATING MATERIAL STANDARDS Col2 MATERIAL STANDARD Acrylic coating ASTM D6083 Silicone coating ASTM D6694 Moisture-cured polyurethane coating ASTM D6947 1507.13.4 Foam plastics. Foam plastic materials and installation shall comply with Chapter 26.
1507.14 Liquid-applied roofing. The installation of liquid-applied roofing shall comply with the provisions of this section. 1507.14.1 Slope. Liquid-applied roofing shall have a design slope of not less than [1] / 4 unit vertical in 12 units horizontal (2-percent slope).
1507.14.2 Material standards. Liquid-applied roofing shall comply with ASTM C836, ASTM C957 or ASTM D3468.
1507.14.3 Application. Liquid-applied roofing shall be installed in accordance with this chapter and the manufacturer’s installation instructions.
1507.15 Vegetative roofs and landscaped roofs. Vegetative roofs and landscaped roofs shall comply with the requirements of this chapter, Section 1607.14 and the California Fire Code.
[BF] 1507.15.1 Structural fire resistance. The structural frame and roof construction supporting the load imposed on the roof by the vegetative roof or landscaped roofs shall comply with the fire-resistance-rating requirements of Table 601.
CRC § 2025 High relevance — show source text
Chapter 9 Roof Assemblies.
Chapter 9 regulates the design and construction of roof assemblies. A roof assembly includes the roof deck, vapor retarder, substrate or thermal barrier, insulation, vapor retarder and roof covering. This chapter provides the requirement for wind resistance of roof coverings.
The types of roof covering materials and installation regulated by Chapter 9 are: asphalt shingles, clay and concrete tile, metal roof shingles, mineral-surfaced roll roofing, slate and slate-type shingles, wood shakes and shingles, built-up roofs, metal roof panels, modified bitumen roofing, thermoset and thermoplastic single-ply roofing, sprayed polyurethane foam roofing, liquid applied coatings and photovoltaic shingles. Chapter 9 also provides requirements for roof drainage, flashing, above deck thermal insulation, rooftop-mounted photovoltaic systems and recovering or replacing an existing roof covering.
Chapter 10 Chimneys and Fireplaces.
Chapter 10 contains requirements for the safe construction of masonry chimneys and fireplaces and establishes the standards for the use and installation of factory-built chimneys, fireplaces and masonry heaters. Chimneys and fireplaces constructed of masonry rely on prescriptive requirements for the details of their construction; the factory-built type relies on the listing and labeling method of approval. Chapter 10 provides the requirements for seismic reinforcing and anchorage of masonry fireplaces and chimneys.
Chapter 11 [RE] Energy Efficiency.
Chapter 11 is not adopted in California. See California Energy Code, Title 24, Part 6.
Chapter 12 Mechanical Administration.
Chapter 12 is not adopted in California. See California Mechanical Code, Title 24, Part 4.
Chapter 13 General Mechanical System Requirements.
Chapter 13 is not adopted in California. See California Mechanical Code, Title 24, Part 4.
Chapter 14 Heating and Cooling Equipment and Appliances.
Chapter 14 is not adopted in California. See California Mechanical Code, Title 24, Part 4.
Chapter 15 Exhaust Systems.
Chapter 15 is not adopted in California. See California Mechanical Code, Title 24, Part 4.
Chapter 16 Duct Systems.
Chapter 16 is not adopted in California. See California Mechanical Code, Title 24, Part 4.
Chapter 17 Combustion Air.
Chapter 17 is not adopted in California. See California Mechanical Code, Title 24, Part 4.
Chapter 18 Chimneys and Vents.
Chapter 18 is not adopted in California. See California Mechanical Code, Title 24, Part 4.
Chapter 19 Special Appliances, Equipment and Systems.
Chapter 19 is not adopted in California. See California Mechanical Code, Title 24, Part 4.
Chapter 20 Boilers and Water Heaters.
Chapter 20 is not adopted in California. See California Mechanical Code, Title 24, Part 4.
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Chapter 21 Hydronic Piping.
Chapter 21 is not adopted in California. See California Mechanical Code, Title 24, Part 4.
Chapter 22 Special Piping and Storage Systems.
Chapter 22 is not adopted in California. See California Mechanical Code, Title 24, Part 4.
Chapter 23 Solar Thermal Energy Systems.
CBC § 4.1 High relevance — show source text
Exceptions: A roof recover shall not be permitted where any of the following conditions occur:
- Where the existing roof or roof covering is water soaked or has deteriorated to the point that the existing roof or roof covering is not adequate as a base for the additional roofing.
- Where the existing roof covering is slate, clay, cement or asbestos-cement title.
- Where the existing roof has two or more applications of any type of roof covering.
R908.4.1 Roof recovering over wood shingles or shakes. Where the application of a new roof covering over wood shingle or shake roofs creates a combustible concealed space, the entire existing surface shall be covered with gypsum board, mineral fiber, glass fiber or other approved materials securely fastened in place.
R908.5 Reinstallation of materials. Existing slate, clay or cement tile shall be permitted for reinstallation, except that damaged, cracked or broken slate or tile shall not be reinstalled. Any existing flashings, edgings, outlets, vents or similar devices that are a part of the assembly shall be replaced where rusted, damaged or deteriorated. Aggregate surfacing materials shall not be reinstalled.
R908.6 Flashings. Flashings shall be reconstructed in accordance with approved manufacturer’s installation instructions. Metal flashing to which bituminous materials are to be adhered shall be primed prior to installation.
SECTION R909—ROOF COATINGS
R909.1 General. The installation of a roof coating on a roof covering shall comply with the requirements of Section R902, Section R904 and this section. Roof coatings shall be installed in accordance with the manufacturer’s installation instructions.
R909.2 Material standards. Roof coating materials shall comply with one of the standards in Table R909.2.
TABLE R909.2—ROOF COATING MATERIAL STANDARDS Col2 COATING MATERIAL STANDARD Acrylic coating ASTM D6083 Asphaltic emulsion coating ASTM D1227 Asphalt coating ASTM D2823 Asphalt roof coating ASTM D4479 Aluminum-pigmented asphalt coating ASTM D2824 Silicone coating ASTM D6694 Moisture-cured polyurethane coating ASTM D6947 9-20 2025 CALIFORNIA RESIDENTIAL CODE
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CALIFORNIA RESIDENTIAL CODE – MATRIX ADOPTION TABLE
CHAPTER 10 – CHIMNEYS AND FIREPLACES
(Matrix Adoption Tables are nonregulatory, intended only as an aid to the code user. See Chapter 1 for state agency authority and building applications.)
Frequently asked questions
Do asphalt shingles need solid sheathing or can they go on spaced sheathing?
Asphalt shingles must be fastened to solidly sheathed decks per § 1507.2.1.
What’s the minimum slope for a single‑ply membrane?
Minimum design slope for single‑ply membranes is 1/4 unit vertical in 12 units horizontal (≈2%) per § 1507.12.1.
When is an ice barrier required and how far must it extend?
Where there is a history of ice forming at eaves, an ice barrier is required and must extend from the lowest roof edge to at least 24 inches inside the exterior wall line (36 inches on steeper eaves as specified) — § 1507.1.2.
Do metal roof panels need special testing for wind?
Yes — metal panel systems applied to a solid deck must be tested per FM 4474, UL 580 or UL 1897; structural metal panels have additional ASTM E1592 testing requirements (§ 1504.4.1–.2).
If my single‑ply is ballasted, does the CBC require anything special?
Ballasted low‑slope single‑ply systems must be designed/installed per § 1507.12.3 and ANSI/SPRI RP‑4 (see § 1504.5 for design direction).
More in California Building Code
- Administration & Permits
- Energy Efficiency
- Existing Buildings
- Occupancy Classification & Use
- Hazardous Materials & Occupancies
- Types of Construction
- Fire-Resistance & Fire Safety
- Interior Finishes
- Means of Egress
- Accessibility
- Exterior Walls
- Roofing & Roof Assemblies
- Structural Design
- Special Inspections & Tests
- Foundations & Soils
- Concrete
- Masonry
- Steel
- Wood
- Elevators & Conveying Systems
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