Millbrae Municipal Code Art. I Building Code

The California Building Code, 2025 Edition, adopted by the California Building Standards Commission, Part 2 Volumes 1 and 2; including Appendix G - Flood-Resistant Construction; Appendix H- Signs; Appendix I-Patio Covers; Appendix J-Grading; Appendix L - Earthquake Recording Instrumentation; hereinafter collectively called the "Building Code," is adopted and by reference incorporated in this chapter as if fully set forth as the building code of the city establishing the rules, regulations and standards within this city as to all matters therein contained; subject, however, to the amendments, additions and deletions set forth in this chapter. The mandatory requirements of the adopted appendices to the Building Code shall be enforceable to the same extent as if contained in the body of the Building Code.

Whenever reference is made within the Millbrae Municipal Code to the Uniform Codes, National Codes or any codes regulating the construction or maintenance of any building, structure or appurtenance thereto, such codes shall commonly mean the currently adopted building code set forth in this chapter.

The building code regulates the erection, construction, enlargement, alteration, repair, moving, removal, demolition, conversion, occupancy, equipment, use, height, area and maintenance of all buildings and structures in the city.

Building Code Section 1.11.2.1.1 is amended by replacing language to read as follows:

1.11.2.1.1 ENFORCEMENT. The responsibility for the enforcement of building standards adopted by the State Fire Marshal and published in the California Building Standards Code relating to fire and panic safety and other regulations of the State Fire Marshal shall, except as provided in Section 1.11.2.1.2, be delegated to the City Building Official for the enforcement of the building standards as they relate to One- and Two-Family Dwellings, as described in Section 310.1 of Part 2 of the California Building Standards Code.

Exception: This section does not apply to Automatic Fire Extinguishing Systems designed and installed in accordance with California Fire Code Section 903.

Building Code Sections 105.1.1 and 105.1.2 are hereby deleted.

Building Code Section [A] 105.2, "2. Fences, other than swimming pool barriers, not over 7 feet (2134 mm) high," is amended to read as follows:

2. Fences that are any manmade barrier forming a physical boundary constructed of wood, concrete, stone, brick, lattice, metal, chain, cable, plastic, or dense planting materials.

Building Code Section 105.3.2 is amended to read as set forth in MMC § 9.05.030.

Building Code Sections 105.5 and 105.5.1 are amended to read as set forth in MMC § 9.05.040.

Building Code Section [A] 109.3 is amended to read as set forth in MMC § 9.05.050.

Building Code Section [A] 113.1 is amended by adding Section 113.1.1 "Appeals" to read as set forth in MMC § 9.05.090.

Building Code Section 202, "Substantial Improvement," is amended to read as follows:

Section 202 SUBSTANTIAL IMPROVEMENT.

Any repair, reconstruction, rehabilitation, alteration, addition or other improvement of a building or structure, which equals or exceeds 50 percent of the existing square footage of the structure before the improvement or repair is started. If the structure has sustained substantial damage, any repairs are considered substantial improvements regardless of the actual repair work performed. The following shall be used to calculate a Substantial Improvement:

1. The square footage of every room repaired, reconstructed, rehabilitated, altered, added or improved shall be included in the calculation of total square footage.

2. The total square footage of an individual room shall be considered repaired, reconstructed, rehabilitated, altered, added to or improved when at least fifty percent (50%) or greater of the linear length of interior wall sheeting or ceiling of any one wall or ceiling within the room is new, removed, or replaced.

a. Aggregate. The square footage of any repair, reconstruction, rehabilitation, alteration, addition or improvement of a building or structure used in calculating whether a Substantial Improvement exists shall not be aggregated with prior or future repairs, reconstructions, rehabilitations, alterations, additions, or improvements in the same building unless the following applies: Where more than one (1) repair, reconstruction, rehabilitation, alteration, addition or improvement for which building permits are required is/are made within a two (2) year period, the sum of the square footage of these repairs, reconstructions, rehabilitations, additions or improvements during the two (2) year period shall be aggregated for the purpose of determining whether there is a Substantial Improvement.

3. The term Substantial Improvement does not, however, include either:

a. Any project for improvement of a building required to correct existing health, sanitary or safety code violation identified by the building official and that are the minimum necessary to assure safe living conditions.

b. Any alteration of a historic structure provided that the alteration will not preclude the structure's continued designation as a historic structure.

Building Code Section 312.1 "Fences more than 7 feet (2134 mm) in height" is amended to read as follows:

Fences that are any manmade barrier forming a physical boundary constructed of wood, concrete, stone, brick, lattice, metal, chain, cable, plastic, or dense planting materials.

Building Code Section 406.6.2 is amended by adding the following section:

Section 406.6.2.1 Garage Ventilation:

A garage containing electrical charging stations shall provide a manually operated control switch that controls ventilation operations located in the command/control room for emergency operations.

Building Code Section [F] 502.1 is amended to read as set forth in MMC § 9.05.160.

Building Code Section 705.2.3 "Exception:" is amended to read as follows:

Exception: Type VA and VB construction shall be allowed for combustible projections in Group R-3 and U occupancies with a fire separation distance greater than or equal to 5 feet measured from the finished face of the building.

Building Code Section 903.1 is amended by adding Sections [F] 903.1.2 and [F] 903.1.3 to read as follows:

Section [F] 903.1.2 Additions and Alterations. The standard for determining the size of addition and/or alteration for determining the threshold for an automatic sprinkler system shall be determined by the following:

1. The square footage of every room being added and/or altered shall be included in the calculation of total square footage of addition and/or alteration.

2. The entire square footage shall be considered added or altered when at least fifty percent (50%) or greater of interior wall sheeting or ceiling of any one wall within a room or area is new, removed, or replaced.

Section [F] 903.1.3 Applicable to all sprinkled buildings.

1. When a commercial or multi-family building is partially retrofitted with an approved automatic fire extinguishing system pursuant to this section, the building owner shall complete the fire extinguishing system retrofit throughout the unprotected building interior areas within six (6) years of completing the initial partial retrofit or within every tenant space where a building permit is obtained, whichever is less.

2. When a residential building is partially retrofitted with an approved automatic sprinkler system pursuant to this section, the building fire extinguishing system retrofit shall be completed throughout the unprotected building interior areas within two (2) years from completing the initial partial retrofit.

3. When a property owner or responsible party of a commercial or residential building chooses option 1 or 2 from above, the property owner shall file a deed restriction with San Mateo County Assessor's Office and obtain a performance bond with Central County Fire Department to ensure compliance with this code.

Building Code Section [F] 903.2 is amended to read as follows:

Section [F] 903.2 Where Required.

Approved automatic fire sprinkler systems shall be installed in all new occupiable and/or habitable buildings and structures. In addition, approved automatic fire sprinkler systems shall be provided in locations described in Sections 903.2.1 through 903.2.23 and Sections 903.2.14 through 903.2.21.

Exceptions:

1. Group U occupancies less than 1200 square feet and separated from the primary structure by a minimum of ten (10) feet.

2. When approved by the fire chief, canopy structures used solely for vehicular parking which have a photovoltaic system attached are not required to be equipped with a fire sprinkler system as long as the structure meets distance requirements to other structures and property lines.

3. Spaces or areas in telecommunications buildings used exclusively for telecommunications equipment, associated electrical power distribution equipment, batteries and standby engines, provided that those spaces or areas are equipped throughout with an automatic smoke detection system in accordance with Section 907.2 and are separated from the remainder of the building by not less than 1-hour fire barriers constructed in accordance with Section 707 or not less than 2-hour horizontal assemblies in accordance with Section 711 or both.

Building Code Section 903.2.10 is amended by adding Section 903.2.10.3 and 903.2.10.4 to read as follows:

[F] 903.2.10.3 Lithium-ion batteries in vehicles.

Areas which contain electric vehicle charging stations shall have a fire sprinkler density design of a minimum extra hazard, group 2 for the coverage of charging stations and for 15' in any direction of charging stations.

Section [F] 903.2.10.4 Additional commercial and multi-family dwelling sprinkler locations. Rooms or spaces which contain vehicle parking lifts or stacking systems shall be designed as Extra-High Hazard Classification. Sprinkler design to include sidewall sprinkler heads designed at minimum Ordinary Group 2 in between each level.

Building Code Section 903.2 is amended by adding Section [F] 903.2.22 to read as follows:

Section [F] 903.2.22 Existing Buildings and Structures.

All existing buildings and structures shall be retroactively protected by an approved automatic extinguishing system when the following conditions exist:

1. Commercial and multi-family residential buildings with a total building floor area in excess of 2,000 square feet or more than two stories in height, and when additions or alterations for which a building permit is required will equal or exceed 1,200 square feet of the existing building square footage.

Exceptions:

a. Group U occupancies less than 1200 square feet and is separated from primary structure by a minimum of ten (10) feet.

b. Building roof repair/replacement; fire damage repair; building heating and/or cooling unit repair/replacement; and any other federal, state and local construction code upgrade requirements including but not limited to the seismic retrofit requirements, asbestos, and other hazardous material abatement.

c. Additions or alterations of commercial and multi-family residential buildings that do not exceed twenty percent (20%) of the total square footage of the entire completed building. The following scopes of work are excluded from calculations to determine area of alteration: building roof repair/replacement, fire damage repair, building heating and/or cooling unit repair/replacement, and any other federal, state, and local construction code upgrade requirements including but not limited to the seismic retrofit requirements, asbestos, and other hazardous material abatement.

Building Code Section 903.2 is amended by adding Section [F] 903.2.23 to read as follows:

Section [F] 903.2.23 Aggregate.

1. When more than one (1) addition and/or alteration for which building permits are required are submitted within a two (2) year period from the closure date of the initial permit, the sum of the square footage of these additions and/or alterations shall be aggregated for the purpose of determining calculations in Section [F] 903.1.2.

Building Code Section 903.3.1 is amended by adding Sections 903.3.1.4, 903.3.1.5 and 903.3.1.6 to read as follows:

Section [F] 903.3.1.4 Inspector's test valves.

Single-family residential fire sprinkler systems within buildings greater than 3600 square feet shall be equipped with an inspector's test valve for each system and located the furthest point away from the sprinkler riser.

Section [F] 903.3.1.5 Additional residential sprinkler locations. The installation of a residential fire sprinkler system shall conform to the following:

1. Sprinklers shall be required throughout carports and garages.

Exception: Detached carports and garages less than 1,200 square feet in area and separated from residential buildings by a minimum of 10 feet.

2. Sprinkler coverage shall be provided in the following locations:

a. Attic access openings.

b. Areas of attics and crawl spaces containing storage, mechanical and/or electrical equipment.

Section 903.3.1.6 ADDITIONAL COMMERCIAL AND MULTI-FAMILY DWELLING SPRINKLER LOCATIONS.

Rooms or spaces which contain vehicle parking lifts or stacking systems shall be designed as Extra-High Hazard Classification. Sprinkler design to include sidewall sprinkler heads designed at minimum Ordinary Group 2 in between each level.

Building Code Section 903.4.1 is amended by adding Section 903.4.1.1 to read as follows:

Section [F] 903.4.1.1 Monitoring.

For new fire sprinkler monitoring systems the approved supervisory station shall be defined as a UL approved central receiving station.

Building Code Section [F] 907.7 is amended to read as follows:

Section [F] 907.7 Acceptance test and completion.

Upon completion of the installation, the fire alarm system and all fire alarm components shall be tested in accordance with NFPA 72. New fire alarm systems installed in commercial and multi-family buildings shall be UL-Certified. Certificate shall be posted next to fire alarm control panel at time of final inspection.

Building Code Table 1505.1 is amended to require all roof coverings to be a minimum Class B assemblies as set forth below.

Building Code Section 1505.1.2 is amended to read as follows:

Section 1505.1.2 Roof covering within all other areas.

The entire roof covering of every existing structure where more than 300 square feet of the total roof area is replaced within any one year period, the entire roof covering of every new structure, and any roof covering applied in the alteration, repair or replacement of a roof of every structure, shall be a fire-retardant roof covering that is a least Class B.

Building Code Section 1705.3 Exceptions number 1, is amended to read as follows.

1. Isolated spread concrete footings of buildings three stories or less above grade plane that are fully supported on earth or rock, where structural design of footing is based on a specified compressive strength f'c, no greater than 2,500 pounds per square inch (psi).

Building Code Section 3005.5 is amended to read as follows:

Section 3005.5. Shunt trip prohibited.

Where elevator hoistways and/or elevator machine rooms, containing elevator control equipment located within buildings equipped with automatic fire sprinklers, the following is required in lieu of a shunt trip:

1. The elevator machine room must be constructed with the minimum fire rating as the hoistway. For non-rated hoistways, the minimum rating must be one hour throughout in accordance with Section 707 of the California Building Code for fire barriers.

2. Fire sprinklers at the top of the hoistway and inside the elevator machine room may not be installed.

3. Means for elevator shutdown may not be installed.