Los Angeles County Municipal Code Ch. 3 Building Planning
Los Angeles County Municipal Code · 2026-09 edition · updated 2026-10-04 · Los Angeles County
Cite as: Los Angeles County Municipal Code Chapter 3 · Text as of 2026-10-04
R301 - DESIGN CRITERIA
R301.1.3.2 - Woodframe structures.
The Building Official shall require construction documents to be approved and stamped by a California licensed architect or engineer for all dwellings of woodframe construction more than two stories and basement in height located in Seismic Design Category A, B, or C. Notwithstanding other sections of law, the law establishing these provisions is found in Business and Professions Code Sections 5537 and 6737.1.
The Building Official shall require construction documents to be approved and stamped by a California licensed architect or engineer for all structural aspects of dwellings of woodframe construction more than one story in height or with a basement located in Seismic Design Category D 0 , D 1 , or D 2 or E.
(Ord. 2025-0051 § 3, 2025.)
R301.1.5 - Seismic design provisions for buildings constructed on or into slopes steeper than one unit vertical in three units horizontal (33.3 percent slope).
The design and construction of new buildings and additions to existing buildings when constructed on or into slopes steeper than one unit vertical in three units horizontal (33.3 percent slope) shall comply with Section 1613.6 of the Los Angeles County Building Code.
(Ord. 2025-0051 § 4, 2025.)
R301.2 - Climatic and geographic design criteria.
Buildings shall be constructed in accordance with the provisions of this Code as limited by the provisions of this Section. Consult with the Building Official regarding additional criteria in Table R301.2.
(Ord. 2025-0051 § 5, 2025.)
R301.2.2.6 - Irregular buildings.
. . .
Shear wall or braced wall offsets out of plane. Conditions where exterior shear wall lines or braced wall panels are not in one plane vertically from the foundation to the uppermost story in which they are required.
Lateral support of roofs and floors. Conditions where a section of floor or roof is not laterally supported by shear walls or braced wall lines on all edges.
Exception: Portions of floors that do not support shear walls, braced wall panels above, or roofs shall be permitted to extend not more than 6 feet (1829 mm) beyond a shear wall or braced wall line.
Shear wall or braced wall offsets in plane. Conditions where the end of a braced wall panel occurs over an opening in the wall below.
Floor and roof opening. Conditions where an opening in a floor or roof exceeds the lesser of 12 feet (3658 mm) or 50 percent of the least floor or roof dimension.
Floor level offset. Conditions where portions of a floor level are vertically offset.
. . .
(Ord. 2025-0051 § 6, 2025.)
R301.2.2.11 - Anchorage of mechanical, electrical, or plumbing components and equipment.
Mechanical, electrical, or plumbing components and equipment shall be anchored to the structure. Anchorage of the components and equipment shall be designed to resist loads in accordance with the Los Angeles County Building Code and ASCE 7, except where the component is positively attached to the structure and flexible connections are provided between the component and associated ductwork, piping, and conduit; and either:
The component weighs 400 pounds (1,780 N) or less and has a center of mass located 4 feet (1.22 m) or less above the supporting structure; or
The component weighs 20 pounds (89N) or less or, in the case of a distributed system, 5 pounds per foot (73 N/m) or less.
(Ord. 2025-0051 § 7, 2025.)
Table R302.1(2) - Exterior Walls—Dwellings, Townhouses and Accessory Buildings with Automatic Residential Fire Sprinkler Protection
For SI: 1 foot = 304.8 mm
a. Reserved.
. . .
(Ord. 2025-0051 § 8, 2025.)
R337 - MATERIALS AND CONSTRUCTION METHODS FOR EXTERIOR WILDFIRE EXPOSURE R337.1 - Modifications to the California Wildland-Urban Interface Code.
Chapter 5 of the California Wildland-Urban Interface Code shall be modified as indicated in Sections 337.1.1 through 337.1.7 and shall apply to all buildings and structures as provided in this section.
(Ord. 2025-0051 § 9, 2025.)
R337.1.1 - California Wildland-Urban Interface Code, Section 501.1.
Modify the California Wildland-Urban Interface Code Section 501.1 to read as follows:
501.1 Scope and Application.
New buildings and structures in a wildland-urban interface area shall be constructed in accordance with the Residential Code and this Code. Additions, alterations, or repairs made to existing buildings erected, constructed, or moved within a Fire Hazard Severity Zone or Wildland-Urban Interface area shall be constructed in accordance with the Residential Code and this code. New buildings for which an application for a building permit is submitted on or after July 1, 2008, and any additions, alterations, or repairs made to existing buildings for which an application for a building permit is submitted on or after January 1, 2026, located in any Fire Hazard Severity Zone or Wildland-Urban Interface area shall comply with all sections of the Residential Code and this Code.
Exceptions:
Group U accessory structures not exceeding 120 square feet (11m 2 ) in floor area where located not less than 50 feet (15 240 mm) from applicable buildings.
Group U agricultural buildings not less than 50 feet (15 240 mm) from applicable buildings.
501.1.1 Alternates for materials, design, tests, and methods of construction.
The Building Official is permitted to modify the provisions of this Chapter for site-specific conditions in accordance with Chapter 1, Section 104.2.2 of the California Wildland-Urban Interface Code.
(Ord. 2025-0051 § 10, 2025.)
R337.1.2 - California Wildland-Urban Interface Code, Section 503.1.
Modify the California Wildland-Urban Interface Code Section 503.1 to read as follows:
503.1 General.
Buildings and structures hereafter constructed, modified or relocated into or within wildland-urban interface areas shall meet the construction requirements in accordance with Chapter 5. Materials required to be ignition-resistant building materials shall comply with the requirements of Section 503.2.
Exceptions:
New accessory buildings and miscellaneous structures complying with Section 504.11.
Reserved.
Group C occupancy special buildings conforming to the limitations specified in Section 450.4.1 of the Building Code.
(Ord. 2025-0051 § 11, 2025.)
R337.1.3 - California Wildland-Urban Interface Code, Section 503.2.3.
Modify the California Wildland-Urban Interface Code Section 503.2.3 to read as follows:
503.2.3 Reserved.
(Ord. 2025-0051 § 12, 2025.)
R337.1.4 - California Wildland-Urban Interface Code, Section 503.3.1.
Modify the California Wildland-Urban Interface Code Section 503.3.1 to read as follows:
503.3.1 Qualification by testing.
Material and material assemblies tested in accordance with the requirements of Section 503 shall be accepted for use when the results and conditions of those tests are met. Product evaluation testing of material and material assemblies shall be approved or listed by the State Fire Marshal, the Building Official, or identified in a current report issued by an approved agency.
(Ord. 2025-0051 § 13, 2025.)
R337.1.5 - California Wildland-Urban Interface Code, Section 503.3.4.
Modify the California Wildland-Urban Interface Code Section 503.3.4 to read as follows:
503.3.4 Reserved.
(Ord. 2025-0051 § 14, 2025.)
R337.1.6 - California Wildland-Urban Interface Code, Section 504.2.1.
Modify the California Wildland-Urban Interface Code Section 504.2.1 to read as follows:
504.2.1 Roof covering voids.
Where there is a void under the roof covering it shall comply with Section 504.2.1.1 or 504.2.1.2. Roof coverings shall be Class A as specified in the Building Code. Wood shingles and wood shakes are prohibited in any Fire Hazard Severity Zone regardless of classification.
(Ord. 2025-0051 § 15, 2025.)
R337.1.7 - California Wildland-Urban Interface Code, Section 504.5.2.
Modify the California Wildland-Urban Interface Code Section 504.5.2 to read as follows:
504.5.2 Exterior wall coverings.
Exterior wall coverings shall comply with one or more of the following requirements:
Noncombustible material.
Ignition-resistant building material labeled for exterior use.
Fire-retardant treated wood labeled for exterior use and complying with the requirements of Section 2303.2 of the Building Code.
Reserved.
Exception:
Exterior wall coverings which are a component of an approved wall assembly complying with Section 504.5.
(Ord. 2025-0051 § 16, 2025.)
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