Hillsborough Municipal Code Ch. 15.04 Building Code

Footnotes:

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Editor's note— Ord. No. 799, § 3(Exh. A), adopted December 9, 2025, in effect repealed Ch. 15.04 and enacted a new Ch. 15.04 as set out herein and as may later be amended. Former Ch. 15.04 pertained to similar subject matter and derived from Ord. No. 690, adopted December 13, 2010; Ord. No. 712, adopted November 12, 2013; Ord. No. 742, adopted November 14, 2016; Ord. No. 757, adopted October 14, 2019; Ord. No. 758, adopted November 12, 2019; Ord. No. 786, adopted 11-28-2022; and Ord. No. 788, adopted January 9, 2023.

The purpose of this chapter is to regulate the construction, alteration, and repair of structures; including materials and design, and to provide for inspections, issuance of permits, collection of fees, imposing of penalties or violations, and adopting uniform rules, regulations and standards in respect thereto.

Sections within this chapter may include both local amendments to Title 24 as adopted therein and local development standards related to construction in the town that are not part of Title 24.

(Ord. No. 799, § 3(Exh. A), 12-9-2025)

The rules, regulations and requirements published as the "2025 California Building Code Volumes 1 and 2," including Appendix Chapters G and J and the state amendments thereto, are hereby adopted as and for the rules, regulations, and standards for the town as to all matters contained therein except as herein otherwise provided.

A. One copy of the 2025 California Building Code Volumes 1 and 2 shall at all times be kept on file at the town building department. It shall be accompanied by one copy of Chapter 15.04 of this code (as well as any additional subsequent amendments) to show the amendments to the 2025 California Building Code Volumes 1 and 2.

B. In the event of any conflict or inconsistency between the provisions of this code and the 2025 California Building Code Volumes 1 and 2, when applied to any particular case, that requirement which establishes the higher degree of safety shall be complied with unless otherwise stated in this code.

C. No provision of the 2025 California Building Code Volumes 1 and 2, or as amended hereby, shall be deemed to supersede any other provision of this code.

(Ord. No. 799, § 3(Exh. A), 12-9-2025)

The 2025 California Building Code Volumes 1 and 2 as adopted by this chapter is hereby amended in its application to the town as set forth within Sections 15.04.040 through 15.04.220.

Any section within 15.04 that modifies the 2025 California Building Code shall include the code section being changed or modified and language which describes the nature of the change or modification. Sections that do not include such reference or language are local development standards and are not amendments to Title 24.

(Ord. No. 799, § 3(Exh. A), 12-9-2025)

Section 109.2 is replaced in its entirety to read as follows:

109.2 Schedule of permit and penalty fees.

A. A fee shall be set forth in the town's master fee schedule, plus any additional fees which may be established or mandated by state or federal law or city ordinance.

B. The value to be used in computing the building permit fee, the plan review fee and other fees shall be the total value of all construction work for which the permit is issued as well as all finish work, painting, roofing, electrical, plumbing, heating, air conditioning, elevators, fire extinguishing systems, etc., and any other permanent construction or equipment.

C. A fee for each permit shall be paid as required, in accordance with the master fee schedule, including subsection (C)(1) and (C)(2) of this section.

1. Whenever a permit fee is required by this chapter to be paid prior to starting work and such work is started prior to obtaining a permit, the scheduled fee shall be the applicable permit fee as set forth in Table No. 1-A found in the master fee schedule, plus an additional amount of up to ten times the applicable permit fee. The exact amount shall be set by the building official in the amount that will, in his or her good faith estimate, recover the cost of town staff time expended to deal with the problems caused by the unpermitted work.

2. If a stop work order is issued, it may not be lifted until a permit reactivation fee has been paid in the amount of not less than two hundred fifty dollars up to one thousand dollars, the exact amount to be set by the building official in the amount that will, in his or her good faith estimate, recover the cost of town staff time expended to deal with the problems involved in the issuance of the stop work order.

3. A document imaging charge shall be charged upon submission of every application for a combination, building, electrical, plumbing, mechanical, grading and or encroachment permit.

(Ord. No. 799, § 3(Exh. A), 12-9-2025)

If a contractor's bond prior to the issuance of any permit for a new residence or other work to which this section is applicable in the opinion of the building official, the applicant shall file with the building official a performance, maintenance or completion bond in the amount of the estimated cost of the work allowed or required under the provisions of the permit. The purpose and intent of the bond is to insure the completion of all work including the installation of any required curbs, gutter, street, sewer, and water; the repair of any damage to any of the above; and the removal of all debris from streets, gutters, sidewalk areas, and job site. Upon completion of the permitted work, such bond shall be exonerated, less any charges against the applicant for any work required to be done or contracted to be done by the town to complete the work.

(Ord. No. 799, § 3(Exh. A), 12-9-2025)

Section 111.2 is amended to read as follows:

111.2 Certificate of occupancy issued. No final inspection by the building official as to all or any portion of a development shall be deemed complete, and no certificate of occupancy or temporary certificate of occupancy shall be issued, nor shall any occupancy occur in accordance with CBC 3312.1, unless and until the installation of the prescribed fire protection facilities and access ways have been completed and approved by the fire chief or designee. Once the prescribed fire protection facilities and access way have been completed and approved as required, and once final inspection by the building official is deemed complete, the building official shall issue a certificate of occupancy containing the address or APN of the property and the name and address of the owner or the owner's agent. The certificate shall also include a description of the portion of the work for which the certificate is being issued and a statement that such work has been inspected for compliance. The Building Official will indicate his/her name and sign the certificate, the code edition under which the work was permitted, whether the structure was required and thus contains an automatic fire sprinkler system, and any further stipulations or conditions that the permit was issued.

(Ord. No. 799, § 3(Exh. A), 12-9-2025)

When required by the fire code official, plans submitted to the building official for a permit shall be reviewed by the fire code official to determine compliance with all applicable standards including the California Fire Code and the California Wildland-Urban Interface Code. Upon review a written report shall be returned to the building official listing deficiencies or compliance with the code.

(Ord. No. 799, § 3(Exh. A), 12-9-2025)

Section 502.1 is replaced in its entirety to read as follows:

502.1 Address identification. New and existing buildings, including accessory dwelling units, shall have approved address numbers, building numbers or approved building identification placed in a position that is plainly legible and visible from the street or road fronting the property. These numbers shall be a minimum of four inches high with minimum stroke width of one-half inch and shall contrast with their background. Address numbers shall be Arabic numerals or alphabet letters. Said numbers shall be either internally or externally illuminated in all new construction. Size of numbers shall be as follows:

1. When the structure is thirty-six (36) to fifty (50) feet from the street or fire apparatus access, a minimum of one-half-inch (½") stroke by six inches (6") high is required.

2. When the structure is more than fifty (50) feet from the street or fire apparatus access, a minimum of one-inch (1") stroke by nine inches (9") high is required.

Multi-Tenant Buildings Address Number. Numbers or letters shall be designated on all occupancies within a building. Size shall be a minimum of one-half inch (½") stroke by four inches (4") high and on a contrasting background. Directional address numbers or letters shall be provided. Said addresses or numbers shall be posted at a height no greater than 5 feet, 6 inches (5'6") above the finished floor and shall be either internally or externally illuminated in all new construction.

Rear addressing. When required by the fire official, approved numbers or addresses shall be placed on all new and existing buildings in such a position as to be plainly visible and legible from the fire apparatus road at the back of a property or where rear parking lots or alleys provide and acceptable vehicular access. Number stroke and size shall comply with 502.1.

(Ord. No. 799, § 3(Exh. A), 12-9-2025)

The standard for calculating whether additions and/or alterations of an existing building which triggers automatic fire sprinkler system installation as described in Section 15.04.112 shall be based on the following criteria:

1. Cumulative Square Footage of Each Room Being Added or Altered.

a. A room is considered added or altered when fifty percent or more of interior wall or ceiling sheeting covering the wall planes of the room is removed, replaced, or new.

b. Wall plane area of a room does not include the area of windows, doors, and openings.

2. Aggregated Additions and Alterations. Cumulative added or altered square footage or replacement costs of additions or alterations will be aggregated to include any room square footage added or altered within a two-year period from the closure date of any previous additions or alterations.

Exceptions:

Wall sheeting removal, replacement, or new installment shall not be calculated when necessitated for:

1. Building roof repair/replacement;

2. Fire damage repair;

3. Building heating and/or cooling unit repair/replacement; and

4. 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.

(Ord. No. 799, § 3(Exh. A), 12-9-2025)

The following provisions apply to all sprinklered buildings:

1. When a non-residential building is partially retrofitted with an approved automatic sprinkler 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 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 fire extinguishing system pursuant to this section, the building fire extinguishing system retrofit shall be completed throughout the unprotected building interior areas within two 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 to ensure compliance. The bond shall be in an amount equal to or greater than the estimated cost of completion, as determined by Central County Fire Department.

(Ord. No. 799, § 3(Exh. A), 12-9-2025)

Section 903.2 is replaced in its entirety to read as follows:

903.2 Where required. Approved automatic fire sprinkler systems shall be provided in locations described in Sections 903.2.1 through 903.2.21 and be installed in:

1. All new occupiable and/or habitable buildings and structures.

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

3. An accessory dwelling unit (ADU) when the primary dwelling that the ADU is in accessory to is required to have or has an existing an automatic residential fire sprinkler system. If an existing primary dwelling is required to have an automatic residential fire sprinkler system, fire sprinklers must be provided throughout both dwellings.

4. All existing buildings and structures. Retroactive protection by an approved automatic extinguishing system shall be required in existing buildings and structures when the following conditions exist:

a. Non-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 and/or alterations for which a building permit is required will exceed 1,500 square feet in area.

b. Structures with a total building floor area in excess of 2,000 square feet or more than two stories in height, and when additions and/or alterations for which a building permit is required will exceed 1,500 square feet in area.

Exceptions:

1. 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 fire protection distance requirements to other structures and property lines.

2. Group U occupancies less than 1,200 square feet.

3. Additions and/or alterations of non-residential and multi-family residential buildings that do not exceed 20% of the total square footage of the entire completed building.

4. Additions and/or alterations to residential one- and two-family dwellings and structures that do not exceed 20% of a building over 7,500 square feet.

5. Additions and/or alterations necessitated for:

a. Building roof repair/replacement;

b. Fire damage repair;

c. Building heating and/or cooling unit repair/replacement; and/or

d. 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

Section 15.04.110 outlines the standard used to calculate additions and/or alterations for purposes of determining applicability of this section.

Section 903.2.10 is amended by adding the following subsection to read as follows:

903.2.10(4) Areas which contain electric vehicle charging stations, and thus could contain lithium-ion batteries in vehicles, 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.

(Ord. No. 799, § 3(Exh. A), 12-9-2025)

Section 903.3 is amended to read as follows:

903.3 Installation requirements. Automatic sprinkler systems shall be designed and installed in accordance with Sections 903.3.1 through 903.3.9. When installed, sprinkler coverage shall be provided in the following locations:

a. Attic access openings

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

(Ord. No. 799, § 3(Exh. A), 12-9-2025)

Section 903.5 is amended to read as follows:

903.5 Inspection, testing and maintenance. Automatic sprinkler systems shall be inspected, tested and maintained in accordance with the California Fire Code. Single-family residential fire sprinkler systems within buildings greater than 3,600 square feet shall be equipped with an inspector's test valve for each system and located the furthest point away from the sprinkler riser.

(Ord. No. 799, § 3(Exh. A), 12-9-2025)

Section 903.2.18 is replaced in its entirety to read as follows:

903.2.18 Group U private garages and carports accessory to Group R-3 occupancies.

Sprinklers shall be required throughout carports and garages. The required residential fire sprinkler shall be in accordance with this section. Residential fire sprinklers shall be connected to, and installed in accordance with, an automatic residential fire sprinkler system that complies with Section R313 of the 2025 California Residential Code or with NFPA 13D. Fire sprinklers shall be residential sprinklers or quick-response sprinklers, designed to provide a minimum density of 0.05 gpm/ft² (2.04 mm/min) over the area of the garage and/or carport, but not exceed two sprinklers for hydraulic calculation purposes. Garage doors shall not considered obstructions with respect to sprinkler placement.

Exception: Detached carports and garages less than 2,000 square feet in area and separated from residential buildings by no less than a minimum of 10 feet.

(Ord. No. 799, § 3(Exh. A), 12-9-2025)

Section 903.4.2 is amended by adding the following condition to read as follows:

903.4.2 Monitoring.

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

(Ord. No. 799, § 3(Exh. A), 12-9-2025)

Section 907.7 is replaced in its entirety to read as follows:

907.7 Acceptance and Certification. 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.

(Ord. No. 799, § 3(Exh. A), 12-9-2025)

Section 1505.1 is replaced in its entirety to read as follows:

1501.1 Minimum roof fire classification. Fire classification of roof assemblies shall be in accordance with Section 1505 as amended. All roof assemblies shall be Class A. All roof assemblies and roof coverings shall be tested in accordance with ASTM E 108 or UL 790. In addition, fire-retardant-treated wood roof coverings shall be tested in accordance with ASTM D 2898 and shall comply with 1505.6. The minimum roof coverings installed on buildings shall comply with the Table 1505.1 as amended.

(Ord. No. 799, § 3(Exh. A), 12-9-2025)

Table No. 1505.1 is replaced in its entirety to read as follows:

TABLE NO. 1505.1 MINIMUM ROOF COVERING CLASSIFICATION FOR TYPES OF CONSTRUCTION

(Ord. No. 799, § 3(Exh. A), 12-9-2025)

Section 1505.1.2 is replaced in its entirety to read as follows:

1505.1.2 Roof covering replacement in all zones. Roof covering within all other areas shall be Class A. The entire roof covering of every existing structure where more than 50 percent 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 the roof of every existing structure, shall be a fire-retardant roof covering that is at least Class A.

(Ord. No. 799, § 3(Exh. A), 12-9-2025)

Except as otherwise provided in this code or as indicated in the town's green infrastructure plan approved by resolution of the city council, in all zones, water from the roof of any building and from any paved area, which would flow by gravity over a public right-of-way, shall be carried by means of conductors under the parking strip area and through the curb to the gutter, or other approved location.

(Ord. No. 799, § 3(Exh. A), 12-9-2025)

No storm water from any roof, impervious surfaces, point discharge or from any paved or developed area shall be allowed to drain to adjacent properties nor shall this water be connected to the city's sanitary sewer system. Regardless of the slope of the source property, such water shall drain to either artificial or natural storm drainage facilities by gravity or pumping.

(Ord. No. 799, § 3(Exh. A), 12-9-2025)

All persons to whom permits are issued pursuant to any provision of this code shall, as a condition to the continuing validity of the permit, maintain the subject building site with proper parking, sanitary facilities, material storage, dust and erosion controls on the property site, including, without limitation, all structures thereon, free of all open trenches, tripping hazards, broken ware, empty cans, rubbish, garbage, metal pieces or parts, and all other refuse (collectively "debris"). The presence of debris is contrary to the purposes and intent of this code and is hereby deemed to pose a threat to the health, property, and public welfare of the town's inhabitants. Violations of the duty to maintain building sites as described herein shall be punishable in the same manner as any other violation of this code.

(Ord. No. 799, § 3(Exh. A), 12-9-2025)

All state provisions and local amendments for existing buildings, including structural evaluation, design, and retrofits of additions, alterations, repairs, and change-of-occupancy work, are now governed by the California Existing Building Code (CEBC), Title 24, Part 10, as adopted by reference and amended in Chapter 15.07 of this code.

(Ord. No. 799, § 3(Exh. A), 12-9-2025)

The following section is added per the direct of the California Office of Emergency Services. These placards are to be used during a "Post Disaster Safety Assessment" performed by the city building staff in the aftermath of any disaster. The post disaster assessment placards carry the weight of law per the direction of the California Office of Emergency Services.

(Ord. No. 799, § 3(Exh. A), 12-9-2025)

A. When, in the judgment of the building department, it is reasonably necessary to amend the provisions of the California Building Code due to local climatic, geological, topographical, or other statutorily permissible conditions, the building official shall prepare and submit the proposed amendments to the city council for consideration at the next regularly scheduled city council meeting. Before adopting any changes or modifications in the requirements contained in the provisions published in the California Building Code, or in any other regulations adopted hereunder, the city council shall make an express finding that such modifications or changes are reasonably necessary because of local climatic, geological, topographical, or other statutorily permissible conditions. Such finding shall be made available as a public record. Upon approval by the city council and filing of the city council's findings with the California Building Standards Commission (CBSC) or other governing body, such amendments shall be added to and become a part of the provisions of this chapter.

B. From October 1, 2025, through June 1, 2031, the town is limited in its ability to modify provisions related to residential units. Allowable findings for modifications during this time are limited to:

1. Modifications previously adopted and filed with the CBSC before September 30, 2025;

2. Administrative changes related to permits or fees;

3. Emergency health and safety measures as deemed by the CBSC;

4. Needed to implement a greenhouse gas emissions reduction strategy as outlined in a general plan adopted before June 10, 2025; or

5. Related to fire home hardening.

(Ord. No. 799, § 3(Exh. A), 12-9-2025)

As successive editions of the California Building Code are promulgated and incorporated by reference in the California Building Standards Code, the building department, under the guidance and direction of the building official, shall review the provisions of the new code in order to determine whether they are consistent with the provisions of the California Building Code then enforce as modified by the provisions of this chapter. The building official shall submit a list of recommendations with respect to such changes (if any) to the city council. Upon review and adoption by the city council, according to the procedure set out in Section 15.04.240, such revised version of the California Building Code, together with all amendments thereto which are recommended by the building official and/or required by the provisions of this chapter, shall govern all buildings and construction within town limits.

(Ord. No. 799, § 3(Exh. A), 12-9-2025)