CBC · California Building Code

What are seismic requirements for cold‑formed steel light‑frame construction?

For homeowners: the California Building Code requires most cold‑formed steel buildings in moderate to high seismic areas to be designed to a higher, seismic‑specific standard (AISI S400) so walls, diaphragms and connections behave predictably in earthquakes; small or lower‑risk systems in SDC B/C sometimes may use the baseline AISI S240 standard, and special inspections and foundation anchorage rules apply in higher seismic zones.

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Last reviewed: July 5, 2026

What the code requires — 2-4 sentences

The California Building Code requires cold‑formed steel light‑frame structural framing (floors, roofs, structural walls, shear walls/diaphragms and trusses) to be designed and installed in accordance with AISI S240 and the specific CBC provisions in Sections 2206.1 through 2206.1.3 (§ 2206.1) . For seismic design, the CBC directs designers to follow the rules in § 2206.1.1 and to use either the B/C provisions ( § 2206.1.1.1 ) or the D–F provisions ( § 2206.1.1.2 ), which essentially require AISI S400 detailing for seismic force‑resisting systems except where a limited exception allows use of AISI S240 in SDC B/C .

Requirements in detail

1) Scope and baseline standard

  • Baseline: Cold‑formed steel light‑frame framing systems must be designed and installed in accordance with AISI S240 and Sections 2206.1.1–2206.1.3 as applicable (§ 2206.1) .
  • This baseline covers floor/roof systems, structural walls, shear walls/diaphragms resisting in‑plane lateral loads, and trusses (§ 2206.1) .

2) Options by Seismic Design Category (SDC)

  • If the project is assigned to Seismic Design Category B or C:
    • Where the designer uses a response‑modification coefficient R in accordance with ASCE 7 Table 12.2‑1, the seismic force‑resisting system must be designed and detailed per AISI S400 (§ 2206.1.1.1) .
    • Exception: The R value for “Steel systems not specifically detailed for seismic resistance, excluding cantilever column systems” in ASCE 7 Table 12.2‑1 is allowed for systems designed and detailed per AISI S240; such systems need not meet AISI S400 detailing (§ 2206.1.1.1, Exception) .
  • If the project is assigned to Seismic Design Category D, E or F:
    • The seismic force‑resisting system must be designed and detailed in accordance with AISI S400 (§ 2206.1.1.2) .
    • Additional OSHPD notes under § 2206.1.1.2 require that cold‑formed steel stud foundation plates or sills be bolted/fastened to the foundation as required in § 2304.3.4, Item 2, and that certain AISI S400 shear‑wall assemblies (Sections E5, E6, E7) are not permitted within the seismic force‑resisting system .

3) Detailing, special inspection and related process requirements

  • The CBC delegates the detailed seismic design and detailing rules to AISI standards (S240, S400) — the CBC cites those standards as the means of compliance; the text does not reproduce detailed connector/ductility requirements, which are in AISI S400/S240 (§ 2206.1, § 2206.1.1, § 2206.1.1.2) .
  • Periodic special inspection is required for welding and for screw/bolt/anchor fastening of elements of the main wind‑ and seismic‑force‑resisting systems for cold‑formed steel light‑frame construction where the structure is in SDC C, D, E or F (§ 1705.12.2 and § 1705.13.3) file.

Decision‑relevant table

Decision factor What the code requires / threshold Code reference
Baseline standard for CFS light‑frame framing Design & installation per AISI S240 (floors, roofs, walls, shear walls/diaphragms, trusses) § 2206.1
SDC B or C — use of ASCE 7 R If R (ASCE 7 Table 12.2‑1) is used, seismic FR system must be designed/detailed per AISI S400 § 2206.1.1.1
SDC B or C — allowed exception Systems using ASCE 7 “Steel systems not specifically detailed…” R may be designed per AISI S240 and need not meet AISI S400 detailing (exception) § 2206.1.1.1 (Exception)
SDC D, E, F Seismic force‑resisting system must be designed and detailed per AISI S400 § 2206.1.1.2
Foundation fastening (OSHPD note) CFS stud foundation plates/sills must be bolted/fastened to foundation per § 2304.3.4, Item 2 § 2206.1.1.2 (OSHPD)
Prohibited shear wall assemblies in seismic FR system AISI S400 shear wall assemblies Sections E5, E6, E7 are not permitted within seismic FR system (OSHPD note) § 2206.1.1.2 (OSHPD)
Special inspections for seismic FR systems Periodic special inspection for welding and fastening of seismic FR elements in SDC C–F § 1705.12.2; § 1705.13.3 file

Exceptions & special cases

  • The CBC explicitly allows an exception in SDC B/C: designers may use the ASCE‑7 R for “Steel systems not specifically detailed for seismic resistance…” and design per AISI S240 (no AISI S400 detailing required) — apply that only where the ASCE 7 table entry is used and the system fits the ASCE definition (§ 2206.1.1.1, Exception) .
  • For projects under OSHPD/DSA jurisdictions additional restrictions appear (e.g., some SDC B/C provisions are “not permitted by DSA‑SS or OSHPD,” and OSHPD adds explicit requirements for foundation anchorage and forbids certain AISI S400 shear‑wall assemblies) — treat these as mandatory where OSHPD/DSA apply (§ 2206.1.1.2 and accompanying notes) .
  • The CBC delegates detailed design and detailing requirements to the referenced AISI standards; the CBC text does not include the AISI‑level detailing rules (you must consult AISI S400/S240 for connection, ductility, yielding and hold‑down details) (§ 2206.1, § 2206.1.1.1, § 2206.1.1.2) file.

If a design decision depends on R values, capacity factors, specific connection details, or allowable drift/ductility limits, those are in the AISI standards and ASCE 7; the retrieved CBC excerpts indicate which standard to use but do not reproduce those numeric/connection details here (§ 2206.1, § 2206.1.1) .

Common mistakes

  • Assuming AISI S240 detailing is always acceptable for seismic design — in many cases (SDC D–F, and B/C when using ASCE‑7 R for seismic‑resistant systems) the CBC requires AISI S400 detailing (§ 2206.1.1.1, § 2206.1.1.2) file.
  • Misapplying the SDC B/C exception: the exception applies only to the specific ASCE 7 table entry (“Steel systems not specifically detailed for seismic resistance…”) — don’t treat it as a blanket waiver for other SDC B/C systems (§ 2206.1.1.1) .
  • Forgetting special inspection requirements for seismic FR elements in SDC C–F (welding and fastenings require periodic special inspection) — check § 1705.12.2 and § 1705.13.3 (§ 1705.12.2; § 1705.13.3) file.
  • Overlooking jurisdictional restrictions (OSHPD/DSA) that may prohibit some CBC allowances (e.g., prescriptive SDC B/C language noted as “Not permitted by DSA‑SS/OSHPD”) — confirm if project is under those authorities (§ 2206.1.1.1 and the A sections) file.
  • Failing to bolt/fasten stud foundation plates or sills per the referenced foundation anchorage rule when OSHPD notes apply (§ 2206.1.1.2 OSHPD note referencing § 2304.3.4 Item 2) .

Worked example — applying the rule with numbers (illustrative)

Scenario: A 4‑story commercial building in California is assigned to Seismic Design Category D. The lateral system is cold‑formed steel light‑frame shear walls and diaphragms.

Application:

  1. Because the building is in SDC D, the CBC requires that the seismic force‑resisting system be designed and detailed in accordance with AISI S400 (§ 2206.1.1.2) . That means all seismic detailing that controls ductility, connection capacity, hold‑downs, collectors, and load paths must comply with the S400 requirements (consult AISI S400 for the explicit connection schedules and detailing rules — those are not printed in the CBC text) (§ 2206.1.1.2) .
  2. Per the OSHPD/CBC note, the cold‑formed steel stud foundation plates or sills must be bolted/fastened to the foundation per § 2304.3.4 Item 2 — confirm anchor type, spacing and embedment per that foundation rule and the project structural drawings (§ 2206.1.1.2 (OSHPD) referencing § 2304.3.4) .
  3. Because the structure is SDC D, periodic special inspection is required for welding and for screw/bolt/anchor fastening of seismic FR elements (shear walls, diaphragms, collectors, hold‑downs) under § 1705.13.3 and § 1705.12.2 — budget for special inspection and include qualifications for the special inspector in the contract documents (§ 1705.12.2; § 1705.13.3) file.
  4. Do not use AISI S400 shear wall assembly types listed as prohibited by OSHPD (for OSHPD projects — Sections E5, E6, E7 are not permitted) — verify allowable assemblies per the jurisdictional notes (§ 2206.1.1.2 OSHPD) .

Note: This example does not compute forces or use numerical R values; the CBC tells you which standard to use (AISI S400) — actual seismic force levels, drift limits and connection capacities come from ASCE 7 and AISI S400 and must be calculated by the registered design professional.

Related provisions

  • § 2206.1 — Structural framing; baseline requirement to use AISI S240 and Sections 2206.1.1–1.3 for cold‑formed steel light‑frame construction .
  • § 2206.1.1 — Seismic requirements (intro directing use of § 2206.1.1.1 or .1.1.2) .
  • § 2206.1.1.1 — Seismic Design Categories B and C requirements and exception for certain ASCE 7 R entry .
  • § 2206.1.1.2 — Seismic Design Categories D through F; requires AISI S400 and includes OSHPD foundation/assembly notes .
  • § 2206.1.2 — Prescriptive framing allowance (AISI S230) for certain detached 1‑ and 2‑family dwellings and townhouses (limitations apply) .
  • § 2206.1.3 — Truss design provisions for cold‑formed steel trusses, including special inspection and design drawing requirements .
  • § 1705.12.2 — Special inspection provisions for cold‑formed steel light‑frame construction (fastening, welding) .
  • § 1705.13.3 — Special inspections for seismic resistance (periodic special inspection for welding and fastening of seismic FR systems in SDC C–F) .
  • § 2304.3.4 (Item 2) — referenced for bolting/fastening stud foundation plates or sills when OSHPD notes apply (see § 2206.1.1.2 OSHPD) .

Code references

Grounded in the retrieved California Building Code — click a citation to read the verbatim passage:

  • CBC § 2206.1 High relevance — show source text

    2206.1 Structural framing. For cold-formed steel light-frame construction, the design and installation of the following structural framing systems, including their members and connections, shall be in accordance with AISI S240, and Sections 2206.1.1 through 2206.1.3, as applicable:

    1. Floor and roof systems.

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    1. Structural walls.

    2. Shear walls, strap-braced walls and diaphragms that resist in-plane lateral loads.

    3. Trusses.

    2206.1.1 Seismic requirements for cold-formed steel structural systems. The design of cold-formed steel light-frame construction to resist seismic forces shall be in accordance with the provisions of Section 2206.1.1.1 or 2206.1.1.2, as applicable.

    2206.1.1.1 Seismic Design Categories B and C. Where a response modification coefficient, R, in accordance with ASCE 7, Table 12.2-1 is used for the design of cold-formed steel light-frame construction assigned to Seismic Design Category B or C, the seismic force-resisting system shall be designed and detailed in accordance with the requirements of AISI S400.

    Exception: The response modification coefficient, R, designated for “Steel systems not specifically detailed for seismic resistance, excluding cantilever column systems” in ASCE 7, Table 12.2-1, shall be permitted for systems designed and detailed in accordance with AISI S240 and need not be designed and detailed in accordance with AISI S400.

    2206.1.1.2 Seismic Design Categories D through F. In cold-formed steel light-frame construction assigned to Seismic Design Category D, E or F, the seismic force-resisting system shall be designed and detailed in accordance with AISI S400.

    [OSHPD 1R, 2 & 5]: 1. Cold-formed steel stud foundation plates or sills shall be bolted or fastened to the foundation or foundation wall in accordance with Section 2304.3.4, Item 2.

    2. Shear wall assemblies in accordance with Sections E5, E6 and E7 of AISI S400 are not permitted within the seismic force- resisting system of buildings.

    2206.1.2 Prescriptive framing. Detached one- and two-family dwellings and townhouses, less than or equal to three stories above grade plane, shall be permitted to be constructed in accordance with AISI S230 subject to the limitations therein.

    2206.1.3 Truss design. Cold-formed steel trusses shall comply with the additional provisions of Sections 2206.1.3.1. through 2206.1.3.3.

    [ OSHPD 1R, 2 & 5] Complete engineering analysis and truss design drawings shall accompany the construction documents submit- ted to the enforcement agency for approval. When load testing is required, the test report shall be submitted with the truss design drawings and engineering analysis to the enforcement agency.

  • CBC § 2204.2.1 High relevance — show source text

    [OSHPD 1R, 2 & 5] Cold-formed steel structures shall be designed and detailed in accordance with the requirements of AISI S100 and AISI S400. Cold-formed steel special bolted moment frames are not permitted by OSHPD.

    2204.2.1 CFS special bolted moment frames. Where a response modification coefficient, R, in accordance with ASCE 7, Table 12.2-1, is used for the design of cold-formed steel special bolted moment frames, the structures shall be designed and detailed in accordance with the requirements of AISI S400.

    2204.2.2 Cold-formed steel seismic force-resisting systems. The response modification coefficient, R, designated in ASCE 7 Table 12.2-1 for “Steel systems not specifically detailed for seismic resistance, excluding cantilever column systems" shall be permitted for systems designed and detailed in accordance with AISI S100. Such systems need not be designed and detailed in accordance with AISI S400.

    SECTION 2205—COLD-FORMED STAINLESS STEEL

    2205.1 General. The design of cold-formed stainless steel structural members shall be in accordance with ASCE 8.

    [OSHPD 1R, 2 & 5] Modify AISI S100 Chapter J (Connections and Joints, Section J7.2) by the following: Power-actuated fastener allow- able design strength shall not exceed that permitted in the evaluation report qualified by ICC AC 70 or ASCE 7, Section 13.4.5.

    SECTION 2206—COLD-FORMED STEEL LIGHT-FRAME CONSTRUCTION

    2206.1 Structural framing. For cold-formed steel light-frame construction, the design and installation of the following structural framing systems, including their members and connections, shall be in accordance with AISI S240, and Sections 2206.1.1 through 2206.1.3, as applicable:

    1. Floor and roof systems.

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    1. Structural walls.

    2. Shear walls, strap-braced walls and diaphragms that resist in-plane lateral loads.

    3. Trusses.

    2206.1.1 Seismic requirements for cold-formed steel structural systems. The design of cold-formed steel light-frame construction to resist seismic forces shall be in accordance with the provisions of Section 2206.1.1.1 or 2206.1.1.2, as applicable.

    2206.1.1.1 Seismic Design Categories B and C. Where a response modification coefficient, R, in accordance with ASCE 7, Table 12.2-1 is used for the design of cold-formed steel light-frame construction assigned to Seismic Design Category B or C, the seismic force-resisting system shall be designed and detailed in accordance with the requirements of AISI S400.

    Exception: The response modification coefficient, R, designated for “Steel systems not specifically detailed for seismic resistance, excluding cantilever column systems” in ASCE 7, Table 12.2-1, shall be permitted for systems designed and detailed in accordance with AISI S240 and need not be designed and detailed in accordance with AISI S400.

  • CBC § 1.1 High relevance — show source text

    SECTION 2205 A —COLD-FORMED STAINLESS STEEL

    2205 A .1 General. The design of cold-formed stainless steel structural members shall be in accordance with ASCE 8.

    SECTION 2206 A —COLD-FORMED STEEL LIGHT-FRAME CONSTRUCTION

    2206 A .1 Structural framing. For cold-formed steel light-frame construction, the design and installation of the following structural framing systems, including their members and connections, shall be in accordance with AISI S240, and Sections 2206 A .1.1 through 2206 A .1.3, as applicable:

    1. Floor and roof systems.

    2. Structural walls.

    3. Shear walls, strap-braced walls and diaphragms that resist in-plane lateral loads.

    4. Trusses.

    2206 A .1.1 Seismic requirements for cold-formed steel structural systems. The design of cold-formed steel light-frame construction to resist seismic forces shall be in accordance with the provisions of Section 2206 A .1.1.1 or 2206 A .1.1.2, as applicable.

    2206 A .1.1.1 Seismic Design Categories B and C. Not permitted by DSA-SS and OSHPD.

    2206 A .1.1.2 Seismic Design Categories D through F. In cold-formed steel light-frame construction assigned to Seismic Design Category D, E or F, the seismic force-resisting system shall be designed and detailed in accordance with AISI S400. The following additional requirements apply: 1. Cold-formed steel stud foundation plates or sills shall be bolted or fastened to the foundation or foundation wall in accordance with Section 2304.3.4, Item 2.

    2. Shear wall assemblies in accordance with Sections E5, E6 and E7 of AISI 400 are not permitted within the seismic force- resisting system of buildings.

    2206 A .1.2 Prescriptive framing. Not permitted by DSA-SS and OSHPD.

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    2206 A .1.3 Truss design. Cold-formed steel trusses shall comply with the additional provisions of Sections 2206 A .1.3.1. through 2206 A .1.3.3.

    Complete engineering analysis and truss design drawings shall accompany the construction documents submitted to the enforce- ment agency for approval. When load testing is required, the test report shall be submitted with the truss design drawings and engineering analysis to the enforcement agency.

  • CBC § 2206.1.1.2 High relevance — show source text

    2206.1.1.2 Seismic Design Categories D through F. In cold-formed steel light-frame construction assigned to Seismic Design Category D, E or F, the seismic force-resisting system shall be designed and detailed in accordance with AISI S400.

    [OSHPD 1R, 2 & 5]: 1. Cold-formed steel stud foundation plates or sills shall be bolted or fastened to the foundation or foundation wall in accordance with Section 2304.3.4, Item 2.

    2. Shear wall assemblies in accordance with Sections E5, E6 and E7 of AISI S400 are not permitted within the seismic force- resisting system of buildings.

    2206.1.2 Prescriptive framing. Detached one- and two-family dwellings and townhouses, less than or equal to three stories above grade plane, shall be permitted to be constructed in accordance with AISI S230 subject to the limitations therein.

    2206.1.3 Truss design. Cold-formed steel trusses shall comply with the additional provisions of Sections 2206.1.3.1. through 2206.1.3.3.

    [ OSHPD 1R, 2 & 5] Complete engineering analysis and truss design drawings shall accompany the construction documents submit- ted to the enforcement agency for approval. When load testing is required, the test report shall be submitted with the truss design drawings and engineering analysis to the enforcement agency.

    2206.1.3.1 Truss design drawings. The truss design drawings shall conform to the requirements of Section I1 of AISI S202 and shall be provided with the shipment of trusses delivered to the job site. The truss design drawings shall include the details of permanent individual truss member restraint/bracing in accordance with Section I1.6 of AISI S202 where these methods are utilized to provide restraint/bracing.

    2206.1.3.2 Trusses spanning 60 feet or greater. The owner or the owner’s authorized agent shall contract with a registered design professional for the design of the temporary installation restraint/bracing and the permanent individual truss member restraint/bracing for trusses with clear spans 60 feet (18 288 mm) or greater. Special inspection of trusses over 60 feet (18 288 mm) in length shall be in accordance with Section 1705.2.

    2206.1.3.3 Truss quality assurance. Trusses not part of a manufacturing process that provides requirements for quality control done under the supervision of a third-party quality control agency in accordance with AISI S240 Chapter D shall be fabricated in compliance with Sections 1704.2.5 and 1705.2, as applicable.

    2206.2 Nonstructural members. For cold-formed steel light-frame construction, the design and installation of nonstructural members and connections shall be in accordance with AISI S220.

    [OSHPD 1R, 2 & 5] for noncomposite assembly design. Where nonstructural members do not qualify for design under AISI S220, the design and installation of nonstructural members and connections shall be in accordance with AISI S240 or S100.

    2206.3 Cutting and notching. The cutting and notching of holes in cold-formed steel framing members shall be in accordance with AISI S240 for structural members and AISI S220 for nonstructural members.

    SECTION 2207—STEEL JOISTS

  • CBC § 2202A.5.2 High relevance — show source text

    2202A.5.2 Section D2. Modify Section D2.6c(b)(2) as follows:

    (2) The moment calculated using the load combinations of the applicable building code, including the amplified seismic load, provided the connection or other mechanism within the column base is designed to have the ductility necessary to accommodate the column base rotation resulting from the design story drift.

    2202A.6 Modifications to AISC 358. [DSA-SS]

    2202A.6.1 Modifications to AISC 358 Chapter 10. [DSA-SS] Steel and concrete ConXtech ConXL composite special moment frame connections shall be permitted, provided: 1. Beams are provided with reduced beam sections (RBS); 2. Web extension to beam web two-sided fillet welds are sized to develop expected strength of the beam web and shall not be less than a [1] / 4 inch fillet weld; and 3. The built-up box column wall thickness shall not be less than 1.25 inches and the HSS column wall thickness shall not be less than [1] / 2 inch.

    SECTION 2203 A —STRUCTURAL STAINLESS STEEL

    2203 A .1 General. The design, manufacture and erection of austenitic and duplex structural stainless steel shall be in accordance with AISC 370.

    SECTION 2204 A —COLD-FORMED STEEL

    2204 A .1 General. The design of cold-formed carbon and low-alloy steel structural members not covered in Sections 2206 A through 2209 A shall be in accordance with AISI S100. The design of cold-formed steel diaphragms shall be in accordance with additional provisions of AISI S310 as applicable.

    SECTION 2205 A —COLD-FORMED STAINLESS STEEL

    2205 A .1 General. The design of cold-formed stainless steel structural members shall be in accordance with ASCE 8.

    SECTION 2206 A —COLD-FORMED STEEL LIGHT-FRAME CONSTRUCTION

    2206 A .1 Structural framing. For cold-formed steel light-frame construction, the design and installation of the following structural framing systems, including their members and connections, shall be in accordance with AISI S240, and Sections 2206 A .1.1 through 2206 A .1.3, as applicable:

    1. Floor and roof systems.

    2. Structural walls.

    3. Shear walls, strap-braced walls and diaphragms that resist in-plane lateral loads.

    4. Trusses.

    2206 A .1.1 Seismic requirements for cold-formed steel structural systems. The design of cold-formed steel light-frame construction to resist seismic forces shall be in accordance with the provisions of Section 2206 A .1.1.1 or 2206 A .1.1.2, as applicable.

    2206 A .1.1.1 Seismic Design Categories B and C. Not permitted by DSA-SS and OSHPD.

  • CBC § 1616.3.2.1. High relevance — show source text

    where:

    w = As defined in Section 1616.3.2.1.

    β T = A coefficient with a value of 16,000 pounds (7200 kN) for structures with masonry bearing walls and a value of 4,000 pounds (1300 kN) for structures with bearing walls of cold-formed steel light-frame construction.

    1616.3.2.4 Vertical ties. Vertical ties shall consist of continuous or spliced reinforcing, continuous or spliced members, wall sheathing or other engineered systems. Vertical tension ties shall be provided in bearing walls and shall be continuous over the height of the building. The minimum nominal tensile strength for vertical ties within a bearing wall shall be equal to the weight of the wall within that story plus the weight of the diaphragm tributary to the wall in the story below. Not fewer than two ties shall be provided for each

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    wall. The strength of each tie need not exceed 3,000 pounds per foot (450 kN/m) of wall tributary to the tie for walls of masonry construction or 750 pounds per foot (140 kN/m) of wall tributary to the tie for walls of cold-formed steel light-frame construction.

    SECTION 1617—ADDITIONAL REQUIREMENTS FOR COMMUNITY COLLEGES [DSA-SS/CC]

    1617.1 Construction documents.

    1617.1.1 Additional requirements for construction documents are included in Sections 4-210 and 4-317 of the California Administra- tive Code (Part 1, Title 24, C.C.R).

    1617.1.2 Connections. Connections that resist design seismic forces shall be designed and detailed on the design drawings.

    1617.1.3 Construction procedures. Where unusual erection or construction procedures are considered essential by the project struc- tural engineer or architect in order to accomplish the intent of the design or influence the construction, such procedure shall be indicated on the plans or in the specifications.

    1617.2 General design requirements.

    1617.2.1 Lateral load deflections.

    1617.2.1.1 Horizontal diaphragms. The maximum span-depth ratio for any roof or floor diaphragm consisting of steel and compos- ite steel slab decking or concrete shall be based on test data and design calculations acceptable to the enforcement agency.

    1617.2.1.2 Veneers. The deflection shall not exceed l/600 for veneered walls, anchored veneers and adhered veneers over 1 inch (25 mm) thick, including the mortar backing.

    1617.2.2 Risk Category of buildings and other structures. Risk Category IV includes structures as defined in the California Adminis- trative Code, Section 4-207 and all structures required for their continuous operation or access/egress.

    1617.2.3 Structural walls . For anchorage of concrete or masonry walls to roof and floor diaphragms, the out-of-plane strength design force shall not be less than 280 lb/linear ft (4.09 kN/m) of wall.

  • CBC § 1.1.1 High relevance — show source text

    2206 A .1.1.1 Seismic Design Categories B and C. Not permitted by DSA-SS and OSHPD.

    2206 A .1.1.2 Seismic Design Categories D through F. In cold-formed steel light-frame construction assigned to Seismic Design Category D, E or F, the seismic force-resisting system shall be designed and detailed in accordance with AISI S400. The following additional requirements apply: 1. Cold-formed steel stud foundation plates or sills shall be bolted or fastened to the foundation or foundation wall in accordance with Section 2304.3.4, Item 2.

    2. Shear wall assemblies in accordance with Sections E5, E6 and E7 of AISI 400 are not permitted within the seismic force- resisting system of buildings.

    2206 A .1.2 Prescriptive framing. Not permitted by DSA-SS and OSHPD.

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    2206 A .1.3 Truss design. Cold-formed steel trusses shall comply with the additional provisions of Sections 2206 A .1.3.1. through 2206 A .1.3.3.

    Complete engineering analysis and truss design drawings shall accompany the construction documents submitted to the enforce- ment agency for approval. When load testing is required, the test report shall be submitted with the truss design drawings and engineering analysis to the enforcement agency.

    2206 A .1.3.1 Truss design drawings. The truss design drawings shall conform to the requirements of Section I1 of AISI S202 and shall be provided with the shipment of trusses delivered to the job site. The truss design drawings shall include the details of permanent individual truss member restraint/bracing in accordance with Section I1.6 of AISI S202 where these methods are utilized to provide restraint/bracing. [DSA-SS] Deferred submittal per Section I1.4.2 of AISI S202 is not permitted by DSA-SS.

    2206 A .1.3.2 Trusses spanning 60 feet or greater. The owner or the owner’s authorized agent shall contract with a registered design professional for the design of the temporary installation restraint/bracing and the permanent individual truss member restraint/bracing for trusses with clear spans 60 feet (18 288 mm) or greater. Special inspection of trusses over 60 feet (18 288 mm) in length shall be in accordance with Section 1705.2.

    2206 A .1.3.3 Truss quality assurance. Trusses not part of a manufacturing process that provides requirements for quality control done under the supervision of a third-party quality control agency in accordance with AISI S240 Chapter D shall be fabricated in compliance with Sections 1704.2.5 and 1705.2, as applicable.

  • CBC § 3.2.1. High relevance — show source text

    where:

    w = As defined in Section 1616 A .3.2.1.

    β T = A coefficient with a value of 16,000 pounds (7200 kN) for structures with masonry bearing walls and a value of 4,000 pounds (1300 kN) for structures with bearing walls of cold-formed steel light-frame construction.

    1616 A .3.2.4 Vertical ties. Vertical ties shall consist of continuous or spliced reinforcing, continuous or spliced members, wall sheathing or other engineered systems. Vertical tension ties shall be provided in bearing walls and shall be continuous over the height of the building. The minimum nominal tensile strength for vertical ties within a bearing wall shall be equal to the weight of the wall within that story plus the weight of the diaphragm tributary to the wall in the story below. Not fewer than two ties shall be provided for each wall. The strength of each tie need not exceed 3,000 pounds per foot (450 kN/m) of wall tributary to the tie for walls of masonry construction or 750 pounds per foot (140 kN/m) of wall tributary to the tie for walls of cold-formed steel light-frame construction.

    SECTION 1617A—MODIFICATIONS TO ASCE 7

    1617A.1 General. The text of ASCE 7 shall be modified as indicated in Sections 1617A.1.1 through 1617A.1.41.

    1617A.1.1 ASCE 7, Section 1.3. Modify ASCE 7, Section 1.3 by adding Section 1.3.8 as follows:

    1.3.8 Structural design criteria. Where design is based on ASCE 7, Chapters 16, 17, 18 or 31, the seismic ground motion, wind tunnel test-based design recommendations, analysis and design methods, material assumptions, testing requirements and acceptance criteria shall be submitted to the enforcement agency as an alternative system.

    [DSA-SS] Peer review requirements in Section 322 of the California Existing Building Code shall apply to design reviews required by ASCE 7, Chapters 17, 18, 31 and ASCE 49.

    [OSHPD 1 & 4] Peer review requirements in Section 1617A.1.41 of this code shall apply to design reviews required by ASCE 7, Chap- ters 17 and 18.

    1617A.1.2 ASCE 7, Section 11.1.3. Replace last paragraph of ASCE 7, Section 11.1.3, by the following:

    Non-building structures similar to buildings shall be designed and detailed in accordance with Chapter 12.

    1617A.1.3 Reserved.

    1617A.1.4 ASCE 7, Table 12.2-1. Modify ASCE 7, Table 12.2-1 as follows:

    A. BEARING WALL SYSTEMS

    6. Intermediate Precast Shear Walls —Not permitted by OSHPD.

    18 . Light-framed walls with shear panels of all other materials —Not permitted by OSHPD and DSA-SS.

    B. BUILDING FRAME SYSTEMS

    1. Steel ordinary concentrically braced frames— Not permitted by OSHPD.
  • CBC § 2202.4.5 High relevance — show source text

    2202.4.5 Modifications to AISC 358 Chapter 15. The DuraFuse Frames (DFF) bolted moment connection shall be permitted, provided: 1. The biaxial dual-strong axis and column minor axis configurations of the moment connection shall be considered as an alternative system. 2. DFF connection bolts shall not slip under wind design demand loads. The connection shall be designed to prevent slip using AISC 360 Equation J3-4, where the slip resistance is taken to be 0.3. 3. Beam flange width-to-thickness ratio shall satisfy AISC 341 Table D1.1b. 4. The beam weight shall be limited to a maximum of 232 pounds per foot (345 kg/m).

    SECTION 2203—STRUCTURAL STAINLESS STEEL

    2203.1 General. The design, manufacture and erection of austenitic and duplex structural stainless steel shall be in accordance with AISC 370.

    SECTION 2204—COLD-FORMED STEEL

    2204.1 General. The design of cold-formed carbon and low-alloy steel structural members not covered in Sections 2206 through 2209 shall be in accordance with AISI S100. The design of cold-formed steel diaphragms shall be in accordance with additional provisions of AISI S310 as applicable. Where required, the seismic design of cold-formed steel structures shall be in accordance with the additional provisions of Section 2204.2.

    2204.2 Seismic design. The design and detailing of cold-formed steel seismic force-resisting systems shall be in accordance with Sections 2204.2.1 and 2204.2.2, as applicable.

    [OSHPD 1R, 2 & 5] Cold-formed steel structures shall be designed and detailed in accordance with the requirements of AISI S100 and AISI S400. Cold-formed steel special bolted moment frames are not permitted by OSHPD.

    2204.2.1 CFS special bolted moment frames. Where a response modification coefficient, R, in accordance with ASCE 7, Table 12.2-1, is used for the design of cold-formed steel special bolted moment frames, the structures shall be designed and detailed in accordance with the requirements of AISI S400.

    2204.2.2 Cold-formed steel seismic force-resisting systems. The response modification coefficient, R, designated in ASCE 7 Table 12.2-1 for “Steel systems not specifically detailed for seismic resistance, excluding cantilever column systems" shall be permitted for systems designed and detailed in accordance with AISI S100. Such systems need not be designed and detailed in accordance with AISI S400.

    SECTION 2205—COLD-FORMED STAINLESS STEEL

    2205.1 General. The design of cold-formed stainless steel structural members shall be in accordance with ASCE 8.

    [OSHPD 1R, 2 & 5] Modify AISI S100 Chapter J (Connections and Joints, Section J7.2) by the following: Power-actuated fastener allow- able design strength shall not exceed that permitted in the evaluation report qualified by ICC AC 70 or ASCE 7, Section 13.4.5.

    SECTION 2206—COLD-FORMED STEEL LIGHT-FRAME CONSTRUCTION

  • CBC § 1705.12.2 High relevance — show source text

    1705.12.2 Cold-formed steel light-frame construction. Periodic special inspection is required for welding operations of elements of the main windforce-resisting system. Periodic special inspection is required for screw attachment, bolting, anchoring and other fastening of elements of the main windforce-resisting system, including shear walls, braces, diaphragms, collectors (drag struts) and hold-downs.

    Exception: Special inspections are not required for cold-formed steel light-frame shear walls and diaphragms, including screwing, bolting, anchoring and other fastening to components of the windforce-resisting system, where either of the following applies:

    1. The sheathing is gypsum board or fiberboard.
    2. The sheathing is wood structural panel or steel sheets on only one side of the shear wall, shear panel or diaphragm assembly and the specified fastener spacing at the panel or sheet edges is more than 4 inches (102 mm) on center (o.c.).

    1705.12.3 Wind-resisting components. Periodic special inspection is required for fastening of the following systems and components:

    1. Roof covering, roof deck and roof framing connections.
    2. Exterior wall covering and wall connections to roof and floor diaphragms and framing.

    1705.13 Special inspections for seismic resistance. Special inspections for seismic resistance shall be required as specified in Sections 1705.13.1 through 1705.13.9, unless exempted by the exceptions of Section 1704.2.

    Exception: The special inspections specified in Sections 1705.13.1 through 1705.13.9 are not required for structures designed and constructed in accordance with one of the following:

    1. The structure consists of light-frame construction; the design spectral response acceleration at short periods, S DS, as determined in Section 1613.2.4, does not exceed 0.5; and the building height of the structure does not exceed 35 feet (10 668 mm).
    2. The seismic force-resisting system of the structure consists of reinforced masonry or reinforced concrete; the design spectral response acceleration at short periods, S DS, as determined in Section 1613.2.4, does not exceed 0.5; and the building height of the structure does not exceed 25 feet (7620 mm).
    3. The structure is a detached one- or two-family dwelling not exceeding two stories above grade plane and does not have any of the following horizontal or vertical irregularities in accordance with Section 12.3 of ASCE 7: 3.1. Torsional or extreme torsional irregularity. 3.2. Nonparallel systems irregularity. 3.3. Stiffness-soft story or stiffness-extreme soft story irregularity. 3.4. Discontinuity in lateral strength-weak story irregularity.

    1705.13.1 Structural steel. Special inspections for seismic resistance shall be in accordance with Section 1705.13.1.1 or 1705.13.1.2, as applicable.

    1705.13.1.1 Seismic force-resisting systems. Special inspections of structural steel in the seismic force-resisting systems in buildings and structures assigned to Seismic Design Category B, C, D, E or F shall be performed in accordance with the quality assurance requirements of AISC 341. [OSHPD 1R, 2 & 5] and this code.

  • CBC § 1617.12.7 High relevance — show source text

    Exception: Structures assigned to Seismic Design Category E or F that have vertical irregularity Type 4a shall be permitted where the story lateral strength is not less than 80 percent of that in the story above.

    1617.12.7 ASCE 7, Section 12.7.2. Modify ASCE 7, Section 12.7.2 by adding Item 7 to read as follows: 7. Where buildings provide lateral support for walls retaining earth, and the exterior grades on opposite sides of the building differ by more than 6 feet (1829 mm), the load combination of the seismic increment of earth pressure due to earthquake acting on the higher side, as determined by a Geotechnical engineer qualified in soils engineering, plus the difference in earth pressures shall be added to the lateral forces provided in this section.

    1617.12.8 ASCE 7, Section 12.10.2.1. Replace Exception to ASCE 7, Section 12.10.2.1 by the following:

    Exception: In light-frame structures or portions thereof braced entirely by wood light-frame shear walls, collector elements and their connections, including connections to vertical elements, need only be designed to resist forces using the load combinations of Section 2.3.6 with seismic forces determined in accordance with Section 12.10.1.1.

    1617.12.9 ASCE 7, Section 12.13.1. Modify ASCE 7, Section 12.13.1 by adding Section 12.13.1.1 as follows:

    12.13.1.1 Foundations and superstructure-to-foundation connections. The foundation shall be capable of transmitting the design base shear and the overturning forces from the structure into the supporting soil. Stability against overturning and sliding shall be in accordance with Section 1605.1.1.

    In addition, the foundation and the connection of the superstructure elements to the foundation shall have the strength to resist, in addition to gravity loads, the lesser of the following seismic loads: 1. The strength of the superstructure elements. 2. The maximum forces that can be delivered to the foundation in a fully yielded structural system. 3. Forces from the Load Combinations with overstrength factor in accordance with ASCE 7, Section 12.4.3.1. Exceptions: 1. Where referenced standards specify the use of higher design loads. 2. When it can be demonstrated that inelastic deformation of the foundation and superstructure-to-foundation connection will not result in a weak story or cause collapse of the structure. 3. Where seismic force-resisting system consists of light-framed walls with shear panels, unless the reference standard specifies the use of higher design loads.

    Where the computation of the seismic overturning moment is by the equivalent lateral-force method or the modal analysis method, reduction in overturning moment permitted by Section 12.13.4 of ASCE 7 may be used.

    Where moment resistance is assumed at the base of the superstructure elements, the rotation and flexural deformation of the foundation as well as deformation of the superstructure-to-foundation connection shall be considered in the drift and deforma- tion compatibility analyses.

    1617.12.10 ASCE 7, Section 12.13.5.2. Modify ASCE 7, Section 12.13.5.2 by the following:

  • CBC § 12.2 High relevance — show source text

    Exceptions: [OSHPD 1R, 2 & 5] Not permitted by OSHPD.

    1. In buildings and structures assigned to Seismic Design Category B or C, special inspections are not required for structural steel seismic force-resisting systems where the response modification coefficient, R, designated for “Steel systems not specifically detailed for seismic resistance, excluding cantilever column systems” in ASCE 7, Table 12.2-1, has been used for design and detailing.

    17-14 2025 CALIFORNIA BUILDING CODE

    on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

    SPECIAL INSPECTIONS AND TESTS

    1. In structures assigned to Seismic Design Category D, E, or F, special inspections are not required for structural steel seismic force-resisting systems where design and detailing in accordance with AISC 360 is permitted by ASCE 7, Table 15.4-1.

    1705.13.1.2 Structural steel elements. Special inspections of structural steel elements in the seismic force-resisting systems of buildings and structures assigned to Seismic Design Category B, C, D, E or F other than those covered in Section 1705.13.1.1, including struts, collectors, chords and foundation elements, shall be performed in accordance with the quality assurance requirements of AISC 341. [OSHPD 1R, 2 & 5] and this code.

    Exceptions: [OSHPD 1R, 2 & 5] Not permitted by OSHPD.

    1. In buildings and structures assigned to Seismic Design Category B or C, special inspections of structural steel elements are not required for seismic force-resisting systems with a response modification coefficient, R, of 3 or less.
    2. In structures assigned to Seismic Design Category D, E, or F, special inspections of structural steel elements are not required for seismic force-resisting systems where design and detailing other than AISC 341 is permitted by ASCE 7, Table 15.4-1. Special inspection shall be in accordance with the applicable referenced standard listed in ASCE 7, Table 15.4-1.

    1705.13.2 Structural wood. For the seismic force-resisting systems of structures assigned to Seismic Design Category C, D, E or F:

    1. Continuous special inspection shall be required during field gluing operations of elements of the seismic force-resisting system.
    2. Periodic special inspection shall be required for nailing, bolting, anchoring and other fastening of elements of the seismic force-resisting system, including wood shear walls, wood diaphragms, drag struts, braces, shear panels and hold-downs.

    Exception: Special inspections are not required for wood shear walls, shear panels and diaphragms, including nailing, bolting, anchoring and other fastening to other elements of the seismic force-resisting system, where the lateral resistance is provided by structural sheathing, and the specified fastener spacing at the panel edges is more than 4 inches (102 mm) on center.

    1705.13.3 Cold-formed steel light-frame construction. For the seismic force-resisting systems of structures assigned to Seismic Design Category C, D, E or F, periodic special inspection shall be required for both:

    1. Welding operations of elements of the seismic force-resisting system.
    2. Screw attachment, bolting, anchoring and other fastening of elements of the seismic force-resisting system, including shear walls, braces, diaphragms, collectors (drag struts) and hold-downs.

Frequently asked questions

Do I always have to use AISI S400 for cold‑formed steel seismic design?

Not always. The CBC requires AISI S400 detailing for seismic force‑resisting systems in SDC D, E or F (§ 2206.1.1.2). For SDC B or C, AISI S400 is required when using an ASCE 7 R value per Table 12.2‑1, but an exception allows some systems to be designed per AISI S240 if they correspond to the ASCE 7 entry “Steel systems not specifically detailed for seismic resistance…” (§ 2206.1.1.1) file.

Where are the AISI connection and ductility rules I need to follow?

The CBC points you to the AISI standards (S240 and S400) for those details; the CBC sections require compliance with those standards but do not reproduce their technical content (§ 2206.1, § 2206.1.1.1, § 2206.1.1.2) file.

Are special inspections required for cold‑formed steel seismic elements?

Yes — periodic special inspection is required for welding and for screw/bolt/anchor fastening of seismic force‑resisting elements for structures in SDC C, D, E or F (§ 1705.12.2; § 1705.13.3) file.

What if my project is under OSHPD or DSA jurisdiction?

OSHPD/DSA may restrict or modify some CBC allowances — the CBC includes jurisdictional notes that, for example, prohibit some prescriptive provisions and add requirements such as bolting of stud sills and forbidding certain AISI S400 shear wall assemblies (§ 2206.1.1.2 and related A‑section notes) file.

If I use the SDC B/C exception, do I still need special inspection?

Special inspection requirements depend on the structure’s SDC and the work performed; the exception to AISI S400 in § 2206.1.1.1 does not automatically remove applicable special inspection obligations — check §§ 1705.12.2 and 1705.13.3 for seismic‑related inspection rules filefile.

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