Optional Revisions Based on Local Experience:
A. Modification or Elimination of the Pre-Construction Notice Requirement.
The current ordinance requires property owners to notify adjacent neighbors by mail at least 30 days before starting any ADU construction. The notice must include detailed project information and contact resources. Property owners must also submit a signed affidavit confirming compliance with the mailing requirement.
The intent of this provision was to promote neighborhood awareness and mitigate surprise or conflict related to ADU construction, even though ADUs are ministerially approved and not subject to public comment or discretionary review.
Observed Challenges:
• The 30-day notice period often causes confusion among neighbors who misinterpret the notice as an opportunity to object or influence the project.
• It has become an administrative burden for both applicants and staff to manage the mailing and affidavit process, with little added value.
• Several applicants have experienced delays in building permit issuance due to issues with the affidavit, despite the ordinance stating the requirement should not delay or deny a project. • State law does not require this step, and its enforceability is questionable if it creates delays or barriers to ministerial approval.
Staff Considerations:
• Eliminate the notice requirement entirely to streamline ADU approvals and align more closely with state law, or
• Modify the requirement to reduce burden and confusion (e.g., reducing the notice period, making it informational only with no affidavit requirement, or shifting the responsibility to the Town).
Council Feedback Requested:
• Should the Town eliminate the pre-construction notice requirement altogether? • If not, would the Council support modifying it to simplify compliance while still encouraging neighborhood awareness?
• Are there alternative approaches Council would like staff to consider for public awareness without creating process friction?
B. Elimination of the Notice of Limited Remaining Development Capacity Requirement The current ordinance requires that, when 500 square feet or fewer of floor area remain under the allowable Floor Area Ratio (FAR), the property owner must record a notice on title. This document (prepared by the Town) serves to inform future owners that additional development potential is limited, and that the Building Division should be consulted before proposing further improvements.
This provision was originally added to provide disclosure to future property owners regarding development constraints, particularly in cases where the addition of an ADU pushes a property close to or beyond its allowable FAR.
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Agenda Staff Report – Hillsborough City Council
September 8, 2025
Observed Challenges:
• Recording a notice on title is a significant legal step that may carry unintended consequences for property resale, refinancing, or buyer perceptions. • The 500-square-foot threshold is somewhat arbitrary and doesn’t necessarily reflect true limitations; future FAR allowances may change or be interpreted differently. • It creates a burden on staff to draft, track, and confirm recordation of these notices, without clear benefit.
• There are already other checks in place (i.e., plan review, zoning analysis) that would flag development constraints when future projects are proposed — without needing to cloud title.
Staff Considerations:
• It may create unwarranted encumbrances on property title. • The same purpose (awareness of limited development potential) can be met through internal permit review procedures without requiring recorded documents. • It is not a requirement of State ADU law and may be seen as overregulation or a barrier to ADU adoption.
Council Feedback Requested:
• Should staff proceed with eliminating this recordation requirement from the ordinance? • Does the Council want to explore alternative notification tools that are less permanent or legalistic (e.g., a note on the approved permit or final inspection sign-off)? C. Modification or Elimination of the Notice of Application Requirement The current ordinance requires property owners to notify adjacent neighbors within three business days of submitting an ADU application. The notice must include project timing and contact information, and the property owner must submit an affidavit of mailing to the Town within one day of completing this step.
This is in addition to a separate Notice of Construction required 30 days before breaking ground.
Observed Challenges:
• Like the construction notice, this provision has led to confusion among neighbors, who may mistakenly believe they can influence or appeal a project through this notice. • It imposes an early administrative burden on applicants, especially given the tight timeline for compliance (3-day window post-submittal).
• Staff time is spent fielding questions from neighbors who misunderstand the purpose of the notice.
• The requirement may conflict with the spirit (and potentially the letter) of state law by adding a procedural step not required under Government Code §65852.2, which mandates streamlined, ministerial approval processes for ADUs.
Staff Considerations:
• Eliminating the Notice of Application requirement altogether. • Consolidating this requirement with the Notice of Construction to avoid duplication. • Retaining an optional or courtesy notice that is Town-issued rather than owner-issued. -171-
Agenda Staff Report – Hillsborough City Council
September 8, 2025
Council Feedback Requested:
• Should the Town eliminate the Notice of Application requirement in its entirety? • Is there support for consolidating this with the Notice of Construction or shifting responsibility to the Town to reduce applicant burden and confusion?
• How important is it to maintain neighborhood awareness at the application stage, even if it creates some administrative friction?
D. Objective Standards that apply only to ADUs that require an ADU planning permit These standards apply only to ADUs requiring a Planning Permit, and they serve as the framework for ensuring compliance with state law while addressing local design considerations. The ADU ordinance presents a timely opportunity for Council to evaluate whether those standards remain appropriate and effective. Including them in this discussion allows Council to consider whether refinements, clarifications, or simplifications are warranted, or whether the current approach should be maintained without change.
1. Architectural Requirements.
a. The materials and colors of the exterior walls, roof, windows, and doors of the ADU must match the materials and colors of the exterior walls, roof, windows, doors of the primary dwelling.
b. The exterior lighting must be limited to down-lights or as otherwise required by the building or fire code.
c. The ADU or JADU must have an independent exterior entrance, apart from that of the primary dwelling.
d. All second-story windows and doors in an ADU that are less than thirty feet from a property line that is not a street line shall either be (for windows) clerestory with the bottom of the glass at least six feet above the finished floor, or (for windows and for doors) utilize frosted or obscure glass.
e. An ADU to be constructed on a lot that has an identified historical resource is subject to the ADU exception process.
f. Outdoor showers are not permitted within setback areas and shall not be visible from adjacent properties or the public right-of-way.
2. Landscape Requirements.
a. The ADU and primary dwelling must use the same driveway to access the street, unless otherwise required for fire apparatus access, as determined by CCFD. b. Evergreen landscape screening must be planted and maintained between the ADU and adjacent parcels as follows:
i. At least one fifteen-gallon size plant shall be provided for every five linear feet of exterior wall. Alternatively, at least one twenty-four-inch box size plant shall be provided for every ten linear feet of exterior wall. This paragraph dictates the minimum number of required plantings, not the particular placement of those plantings.
ii. For a ground-level ADU, plant specimens must be at least six feet tall when installed. As an alternative, for a ground-level ADU, a solid fence of at least six feet in height may be installed.
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Agenda Staff Report – Hillsborough City Council
September 8, 2025
iii. For a second-story ADU, plant specimens must be at least twelve feet tall when installed.
Staff Considerations:
Staff is not proposing specific edits at this time. However, because the ordinance is under review, this is an opportunity for Council to evaluate whether the existing objective standards remain appropriate, need refinement, or should be simplified for clarity.
Council Feedback Requested:
• Should the Town retain the current objective standards as written? • Does the Council wish to modify or clarify any standards? • Are there particular design elements Council believes should be strengthened, removed, or more clearly defined?
NEXT STEPS
• Incorporate City Council feedback into a revised draft ordinance. • Return to City Council with a formal ordinance for introduction and adoption.
FISCAL IMPACT: There is no fiscal impact associated with this agenda item.
ENVIRONMENTAL ISSUES: The proposed action is exempt from environmental review pursuant to the California Environmental Quality Act (CEQA) Guidelines sections 15378(b)(2) and 15378(b)(5) as ongoing administrative or organizational activities that will not result in direct or indirect physical changes in the environment.
ATTACHMENT: HMC Chapter 17.52 - Accessory Dwelling Units and Junior Accessory Dwelling Units
PREPARED BY: Liz Ruess, Assistant Director of Building & Planning RECOMMENDATION: Receive a presentation on potential revisions to the Hillsborough Municipal Code related to Accessory Dwelling Units (ADUs) and provide feedback and direction to staff regarding proposed changes.
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Chapter 17.52 ACCESSORY DWELLING UNITS AND JUNIOR ACCESSORY
DWELLING UNITS
17.52.010 Definitions.
As used in this chapter, terms are defined as follows:
"Accessory dwelling unit" or "ADU" means an attached or a detached residential dwelling unit that provides complete independent living facilities for one or more persons and is located on a lot with a proposed or existing primary residence. All references in this code to "second unit" refer to an ADU. An accessory dwelling unit also includes the following:
1. An efficiency unit, as defined by Section 17958.1 of the California Health and Safety Code; and
2. A manufactured home, as defined by Section 18007 of the California Health and Safety Code. "Accessory structure" means a structure that is accessory and incidental to a dwelling located on the same lot.
"Complete independent living facilities" means permanent provisions for living, sleeping, eating, cooking, and sanitation on the same parcel as the single-family or multifamily dwelling is or will be situated. "Efficiency kitchen" means a kitchen that includes each of the following:
1. A cooking facility with appliances.
2. A food preparation counter and storage cabinets that are of a reasonable size in relation to the size of the JADU.
"Junior accessory dwelling unit" or "JADU" means a residential unit that:
1. Is no more than five hundred square feet in size.
2. Is contained entirely within an existing or proposed single-family structure. An enclosed use within the residence, such as an attached garage, is considered to be a part of and contained within the singlefamily structure.
3. Includes its own separate sanitation facilities or shares sanitation facilities with the existing or proposed single-family structure.
4. If the unit does not include its own separate bathroom, then it contains an interior entrance to the main living area of the existing or proposed single-family structure in addition to an exterior entrance that is separate from the main entrance to the primary dwelling.
5. Includes an efficiency kitchen, as defined above.
"Livable space" means a space in a dwelling intended for human habitation, including living, sleeping, eating, cooking, or sanitation.
"Living area" means the interior habitable area of a dwelling unit, including basements and attics, but does not include a garage or any accessory structure.
"Nonconforming zoning condition" means a physical improvement on a property that does not conform with current zoning standards.
"Passageway" means a pathway that is unobstructed clear to the sky and extends from a street to one entrance of the ADU or JADU.
"Proposed dwelling" means a dwelling that is the subject of a permit application and that meets the requirements for permitting.
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"Public transit" means a location, including, but not limited to, a bus stop or train station, where the public may access buses, trains, subways, and other forms of transportation that charge set fares, run on fixed routes, and are available to the public.
"Tandem parking" means that two or more automobiles are parked on a driveway or in any other location on a lot, lined up behind one another.
(Ord. No. 763, § 3(Exh. A), 1-13-2020; Ord. No. 768, § 3(Exh. A), 3-8-2021; Ord. No. 777, § 3(Exh. A), 12-13-2021; Ord. No. 787, 12-12-2022; Ord. No. 796, § 4(Exh. A), 12-9-2024)
17.52.020 General provisions.
A. Purpose. The purpose of this chapter is to allow and regulate ADUs and JADUs in compliance with Chapter 13 of Division 1 of Title 7 of the California Government Code.
B. Effect of Conforming. An ADU or JADU that conforms to the standards in this section will not be:
1. Deemed to be inconsistent with the town's general plan and zoning designation for the lot on which the ADU or JADU is located.
2. Deemed to exceed the allowable density for the lot on which the ADU or JADU is located.
3. Considered in the application of any local ordinance, policy, or program to limit residential growth.
4. Required to correct a nonconforming zoning condition, as defined in Section 17.52.010. This does not prevent the town from enforcing compliance with applicable building standards in accordance with Health and Safety Code Section 17980.12.
C. Approvals. The following approvals apply to ADUs and JADUs under this section:
1. Building Permit Only. If an ADU or JADU complies with each of the general requirements in subsection D below, it is allowed with only a building permit in the following scenarios:
a. Converted on Single-family Lot: one ADU as described in this subsection and one JADU on a lot with a proposed or existing single-family dwelling on it, where the ADU or JADU:
(1) Is either: within the space of a proposed single-family dwelling; within the existing space of an existing single-family dwelling; or within the existing space of an accessory structure, plus up to one hundred fifty additional square feet if the expansion is limited to accommodating ingress and egress may utilize reduced ADU setbacks. An expansion for purposed other than accommodating ingress and egress must comply with applicable setbacks.
(2) Has exterior access that is independent of that for the single-family dwelling. (3) Has side and rear setbacks sufficient for fire and safety, as dictated by applicable building and fire codes.
(4) The JADU complies with the requirements of Government Code sections 66333 through 66339.
b. Limited Detached on Single-family Lot: one detached, new-construction ADU on a lot with a proposed or existing single-family dwelling (in addition to any JADU that might otherwise be established on the lot under subsection C.1.a. above), if the detached ADU satisfies the following limitations:
(1) The side- and rear-yard setbacks are at least four feet from the property line. (2) The total floor area is eight hundred square feet or smaller. -175-
(3) The peak height above grade does not exceed the applicable height limit in subsection E.6 below.
c. Converted on Lot with Multifamily: one or more ADUs within portions of existing multifamily dwelling structures that are not used as livable space, including but not limited to storage rooms, boiler rooms, passageways, attics, basements, or garages, if each converted ADU complies with state building standards for dwellings. Under this subsection C.1.c., at least one converted ADU is allowed within an existing multifamily dwelling, up to a quantity equal to twenty-five percent of the existing multifamily dwelling units.
d. Limited Detached with Multifamily: no more than two detached ADUs on a lot with a proposed multifamily dwelling, or up to eight detached ADUs on a lot with an existing multifamily dwelling, if each detached ADU satisfies both of the following limitations:
(1) The side- and rear-yard setbacks are at least four feet. If the existing multifamily dwelling has a rear or side yard setback of less than four feet, the city will not require any modification to the multifamily dwelling as a condition of approving the ADU. (2) The peak height above grade does not exceed the applicable height limit provided in subsection E.6. below
(3) If the lot has an existing multifamily dwelling, the quantity of detached ADUs does not exceed the number of primary dwelling units on the lot.
2. ADU Planning Permit.
a. Except as allowed under subsection C.1. (building permit only), no ADU may be created without an ADU planning permit and a building permit in compliance with the standards set forth in subsections D. (ADU and JADU requirements) and E. (ADU planning permit requirements), below. b. The town may charge a fee to reimburse it for costs incurred in processing ADU planning permits, including the costs of adopting or amending the town's ADU ordinance. The ADU planning permit processing fee is determined by the town council by resolution.
D. ADU and JADU Requirements. The following requirements apply to all ministerial ADUs and JADUs that are applied for under subsections C.1. (building permit only) or C.2. (ADU planning permit) above:
1. Zoning.
a. An ADU or JADU subject only to a building permit under subsection C.1. above may be created on a lot in a residential or mixed-use zone.
b. An ADU or JADU subject to an ADU permit under subsection C.2. above may be created on a lot that is zoned to allow single-family dwelling residential use. c. In accordance with Government Code section 66333(a), a JADU may only be created on a lot zoned for single-family residences.
2. Fire Sprinklers.
a. Fire sprinklers are required in an ADU if sprinklers are required in the primary residence. b. The construction of an ADU does not trigger a requirement for fire sprinklers to be installed in the existing primary dwelling.
3. Rental.
a. No ADU or JADU may be rented for a term that is shorter than thirty days. This prohibition applies regardless of when the ADU or JADU was created. b. The renting of the primary dwelling, ADU, or JADU is not considered a business and is not subject to the provisions of Chapter 5.04.
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4. No Separate Conveyance. An ADU or JADU may be rented, but except as otherwise provided in Government Code Section 66341, no ADU or JADU may be sold or otherwise conveyed separately from the lot and the primary dwelling (in the case of a single-family lot) or from the lot and all of the dwellings (in the case of a lot with multifamily).
5. Owner Occupancy.
a. ADUs created under this section on or after January 1, 2020 are not subject to an owneroccupancy requirement. b. As required by state law, all JADUs are subject to an owner-occupancy requirement. A natural person with legal or equitable title to the property must reside on the property, in either the primary dwelling or JADU, as the person's legal domicile and permanent residence. However, the owner-occupancy requirement of this subsection does not apply if the property is entirely owned by another governmental agency, land trust, or housing organization.
6. Deed Restriction. Prior to issuance of a certificate of occupancy for an ADU or JADU, a deed restriction must be recorded against the title of the property in the county recorder's office and a copy filed with the town. Evidence of recordation is not required for issuance of a building permit or ADU permit. The deed restriction must run with the land and bind all future owners. The form of the deed restriction will be provided by the town and must provide that:
a. Except as otherwise provided in Government Code Section 66341, the ADU or JADU may not be sold separately from the primary dwelling.
b. The ADU or JADU is restricted to the approved size and to other attributes allowed by this section.
c. The deed restriction runs with the land and may be enforced against future property owners. d. The deed restriction may be removed if the ADU or JADU is entirely physically removed. The remaining structure and improvements must otherwise comply with applicable provisions of this code.
e. The deed restriction is enforceable by the director or his or her designee for the benefit of the town. Failure of the property owner to comply with the deed restriction may result in legal action against the property owner, and the town is authorized to obtain any remedy available to it at law or equity, including, but not limited to, obtaining an injunction enjoining the use of the ADU or JADU in violation of the recorded restrictions or abatement of the illegal unit.
7. Rent Reporting. In order to facilitate the town's obligation to identify adequate sites for housing in accordance with Government Code Sections 65583.1 and 66330, the following requirements must be satisfied:
a. With the building permit application, the applicant must provide the town with an estimate of the projected annualized rent that will be charged for the ADU or JADU. b. Within ninety days after each January 1 following issuance of the building permit, the owner must report the actual rent charged for the ADU or JADU during the prior year. If the town does not receive the report within the ninety-day period, the owner is in violation of this code, and the town may send the owner a notice of violation and allow the owner another thirty days to submit the report. If the owner fails to submit the report within the thirty-day period, the town may enforce this provision in accordance with applicable law. c. This requirement shall not be the basis for the delay or denial of an ADU application.
8. Notice of Construction.
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a. At least thirty calendar days before starting any construction of an ADU, the property owner shall mail written notice to all the owners of record of each of the adjacent residential parcels, utilizing the mail notice template provided by the town, which shall include the following information:
(1) Notice that construction has been authorized,
(2) The anticipated start and end dates for construction, (3) The hours of construction,
(4) Contact information for the project manager (for construction-related complaints), and (5) Contact information for the town building division. b. Within one business day of completion of mailing, the property owner shall submit to the building division a completed and signed affidavit of mailing, utilizing the affidavit of mailing template provided by the town.
c. This notice requirement does not confer a right on the noticed persons or on anyone else to comment on the project before permits are issued. Approval is ministerial. Under state law, the town has no discretion in approving or denying a particular ADU project under this section. This notice requirement is purely to promote neighborhood awareness and expectation. d. This requirement shall not be the basis for the delay or denial of an ADU application.
9. Building and Safety.
a. Must Comply with Building Code. Subject to subparagraph 9.b. below, all ADUs and JADUs must comply with all local building and fire code requirements. b. No Change of Occupancy. Construction of an ADU does not constitute a group R occupancy change under the local building code, as described in Section 310 of the California Building Code, unless the building official makes a written finding based on substantial evidence in the record that the construction of the ADU could have a specific, adverse impact on public health and safety. Nothing in this subsection E.9.b. prevents the city from changing the occupancy code of a space that was uninhabitable space or that was only permitted for nonresidential use and was subsequently converted for residential use in accordance with this section.
10. Structures and Equipment within Setbacks. No structures or mechanical equipment may be located within the ADU setback area.
E. ADU Planning Permit Review Requirements. The following requirements apply only to ADUs that require an ADU planning permit as described under subsection C.2. above.
1. Maximum Size.
a. The maximum size of a detached or attached ADU subject to this subsection E is as follows:
(1) Eight hundred fifty square feet for a studio or one-bedroom unit; and (2) One thousand square feet for an ADU with two or more bedrooms. b. An attached ADU that is created on a lot with an existing primary dwelling is further limited to fifty percent of the floor area of the existing primary dwelling. c. Application of other development standards in this subsection E, such as FAR or lot coverage, might further limit the size of the ADU, but no application of the percent-based size limit in subsection E.1.b above or of an FAR, front setback, lot coverage, and open-space requirement may require the ADU to be less than eight hundred square feet.
2. Floor Area Ratio (FAR). For each ADU that is subject to this subsection E, the total covered floor area of all dwellings and structures on the lot may not exceed twenty-five percent of the net lot area for the first acre, plus fifteen percent of the net lot area over one acre, subject to subsection E.1.c. above. This -178-
percentage is known as the floor-area ratio (FAR) and is calculated by dividing the total covered floor area (in square feet) by the net lot area (also in square feet).
3. Lot Coverage. Subject to subsection E.1.c. above, ADUs are subject to lot coverage limits. For purposes of this chapter, there are two types of residential lot coverage limits to which ADUs are subject together with the other dwelling and structures on the lot. These types are: structural coverage and hardscape coverage.
a. Structural Coverage.
(1) Structural coverage consists of areas of the lot covered by a dwelling, a garage, a carport, and any other accessory structure having a roof and more than one wall. (2) The maximum structural coverage of a lot is as follows:
Table 17.52.020-1
Lot size
(net lot area)
Maximum area of lot
permitted to be covered
Up to 17,500 sq. ft. 22 sq. ft. for each 100 sq. ft. or portion thereof of net lot area 17,500 up to 21,780 sq. ft. 3,850 sq. ft. plus 15 sq. ft. for each 100 sq. ft. or portion thereof of net lot area in excess of 17,500 sq. ft.
21,780 up to 32,670 sq. ft. 4,495 sq. ft. plus 10 sq. ft. for each 100 sq. ft. or portion thereof of net lot area in excess of 21,780 sq. ft.
32,670 through 43,560 sq. ft. 5,585 sq. ft. plus 6 sq. ft. for each 100 sq. ft. or portion thereof of net lot area in excess of 32,670 sq. ft.
Over 43,560
sq. ft.
6,239 sq. ft. plus 5 sq. ft. for each 100 sq. ft. or portion thereof of net lot area in excess of 43,560 sq. ft.
b. Hardscape.
(1) Hardscape coverage consists of areas of the lot located beneath a roof or covered by manufactured, non-plant, pervious or impervious materials but does not include anything included in structural coverage.
(2) Examples include, but are not limited to: decking, a concrete slab or walkway, a gazebo with no walls (just a roof).
c. Subject to the provisions of subsection E.3.a. above, the combined total of structural plus hardscape coverage shall not exceed fifty percent of the net lot area; provided, however, that in any setback area adjacent to the street line, the combined total of structural plus hardscape coverage may not exceed forty percent of such area.
4. Minimum Open Space. No ADU subject to this subsection E. may cause the total percentage of open space of the lot to fall below fifty percent, subject to subsection E.1.c. above.
5. Notice of Limited Remaining Development Capacity. When five hundred or fewer square feet remain in the allowable floor area, a notice (prepared by the town) shall be recorded by the property owner to notify future owners that the square footage remaining for additional development of the property is minimal and that the building department should therefore be consulted as to whether any additional development is possible on the property.
6. Height.
a. Detached.
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(1) Except as otherwise provided by subsections E.6.a.2. and E.6.a.3. below, a detached ADU created on a lot with an existing or proposed single-family or multifamily dwelling unit may not exceed sixteen feet in height.
(2) A detached ADU may be up to eighteen feet in height if it is created on a lot with an existing or proposed single-family dwelling unit that is located within one-half mile walking distance of a major transit stop or a high quality transit corridor, as those terms are defined in Section 21155 of the Public Resources Code, and the ADU may be up to two additional feet in height (for a maximum of twenty feet) if necessary to accommodate a roof pitch on the ADU that is aligned with the roof pitch of the primary dwelling unit. (3) The height of a detached ADU that is at least twenty feet from side and rear property lines, and at least twenty-five feet from all public right-of-way may be up to twenty-two feet in height, measured from existing grade, defined by subsection E.6.c. below. (4) A detached ADU created on a lot with an existing or proposed multifamily dwelling that has more than one story above grade may not exceed 18 feet in height. b. Attached. An ADU that is attached to the primary dwelling may not exceed twenty-five feet or the height limitation in the local zoning ordinance that applies to the primary dwelling, whichever is lower. Notwithstanding the foregoing, ADUs subject to this subsection E.6.b. may not exceed two stories.
c. For purposes of this subsection E.6., height is measured above existing grade. "Existing grade" means the legally established grade that exists at the time that the application is submitted.
7. Setback.
a. Side and Rear. ADUs that are subject to this subsection E. must conform to minimum four-foot side and rear setbacks.
b. Front. ADUs that are subject to this subsection E. must conform to twenty-five-foot front setbacks.
c. No setback is required for an ADU that is subject to this subsection E. if the ADU is constructed in the same location and to the same dimensions as an existing structure.
8. Passageway. No passageway, as defined by subsection H. above, is required for an ADU.
9. Parking.
a. Generally. One off-street parking space is required for each ADU. The parking space may be provided in setback areas or as tandem parking, as defined by subsection K. above. The town may restrict tandem parking or parking in setback areas in certain areas or throughout the town if the town finds that such parking configurations are not feasible based upon specific site or regional topographic or fire and life safety conditions.
b. Exceptions. No parking under subsection E.9.a. is required in the following situations:
(1) The ADU is located within one-half mile walking distance of public transit, as defined in subsection J. above.
(2) The ADU is located within an architecturally and historically significant historic district. (3) The ADU is part of the proposed or existing primary residence or an accessory structure under subsection C.1.a. above.
(4) When on-street parking permits are required but not offered to the occupant of the ADU. (5) When there is an established car share vehicle stop located within one block of the ADU. -180-
(6) When the permit application to create an ADU is submitted with an application to create a new single-family or new multifamily dwelling on the same lot, provided that the ADU or the lot satisfies any other criteria listed in subsections E.9.b.1. through 5. above. c. No Replacement. When a garage, carport, or covered parking structure is demolished in conjunction with the construction of an ADU or converted to an ADU, those off-street parking spaces are not required to be replaced.
10. Architectural Requirements.
a. The materials and colors of the exterior walls, roof, windows, and doors of the ADU must match the materials and colors of the exterior walls, roof, windows, and doors of the primary dwelling. b. The exterior lighting must be limited to down-lights or as otherwise required by the building or fire code.
c. The ADU or JADU must have an independent exterior entrance, apart from that of the primary dwelling.
d. All second-story windows and doors in an ADU that are less than thirty feet from a property line that is not a street line shall either be (for windows) clerestory with the bottom of the glass at least six feet above the finished floor, or (for windows and for doors) utilize frosted or obscure glass.
e. An ADU to be constructed on a lot that has an identified historical resource is subject to the ADU exception process.
f. Outdoor showers are not permitted within setback areas and shall not be visible from adjacent properties or the public right-of-way.
11. Landscape Requirements.
a. The ADU and primary dwelling must use the same driveway to access the street, unless otherwise required for fire apparatus access, as determined by CCFD. b. Evergreen landscape screening must be planted and maintained between the ADU and adjacent parcels as follows:
(1) At least one fifteen-gallon size plant shall be provided for every five linear feet of exterior wall. Alternatively, at least one twenty-four-inch box size plant shall be provided for every ten linear feet of exterior wall. This paragraph dictates the minimum number of required plantings, not the particular placement of those plantings. (2) For a ground-level ADU, plant specimens must be at least six feet tall when installed. As an alternative, for a ground-level ADU, a solid fence of at least six feet in height may be installed.
(3) For a second-story ADU, plant specimens must be at least twelve feet tall when installed.
12. Roof Decks. Roof decks are prohibited on any ADU.
13. Notice of Application.
a. Within three business days of submitting an application for an ADU under this section, the property owner shall mail written notice to all the owners of record of each of the adjacent residential parcels, utilizing the mail notice template provided by the town, which shall include the following information:
(1) Notice that an ADU planning permit application has been submitted; (2) The anticipated start and end dates for construction; (3) Contact information for the town planning division; and -181-
(4) Contact information for the property owner.
b. Within one business day of completion of mailing, the property owner shall submit to the building division a completed and signed affidavit of mailing, utilizing the affidavit of mailing template provided by the town.
c. This notice requirement does not confer a right on the noticed persons or on anyone else to comment on the project before permits are issued. Approval is ministerial. Under state law, the town has no discretion in approving or denying a particular ADU project under this section. This notice requirement is purely to promote neighborhood awareness and expectation.
F. Impact Fees.
1. No impact fee is required for an ADU that is less than seven hundred fifty square feet in size. For purposes of this subsection F.1., "impact fee" means a "fee" under the Mitigation Fee Act (Government Code Section 66000(b)) and a fee under the Quimby Act (Government Code Section 66477). "Impact fee" here does not include any connection fee or capacity charge for water or sewer service.
2. Any impact fee that is required for an ADU that is seven hundred fifty square feet or larger in size must be charged proportionately in relation to the square footage of the primary dwelling unit (e.g. the floor area of the primary dwelling, divided by the floor area of the ADU, times the typical fee amount charged for a new dwelling). "Impact fee" here does not include any connection fee or capacity charge for water or sewer service.
G. Process and Timing.
1. Building permit only and ADU planning permit applications are considered and approved ministerially, without discretionary review or a hearing.
2. The town shall approve or deny the application to create an ADU or JADU within sixty days from the date that the town deems an application complete. If the town does not act upon the completed application within sixty days, the application is deemed approved unless either:
a. The applicant requests a delay, in which case the sixty-day time period is tolled for the period of the requested delay; or
b. When an application to create an ADU or JADU is submitted with a permit application to create a new single-family or multifamily dwelling on the lot, the town may delay acting on the permit application for the ADU or JADU until the town acts on the permit application to create the new single-family or multifamily dwelling, but the application to create the ADU or JADU will still be considered ministerially without discretionary review or a hearing.
3. If the town denies an application to create an ADU or JADU, the city must provide the applicant with comments that include, among other things, a list of all the defective or deficient items and a description of how the application may be remedied by the applicant. Notice of the denial and corresponding comments must be provided to the applicant within the sixty-day time period established by subsection G.2. above.
4. A demolition permit for a detached garage that is to be replaced with an ADU is reviewed with the application for the ADU and issued at the same time.
H. Nonconforming Zoning Code Conditions, Building Code Violations, and Unpermitted Structures.
1. Generally. The city will not deny an ADU or JADU application due to a nonconforming zoning condition, building code violation, or unpermitted structure on the lot that does not present a threat to the public health and safety and that is not affected by the construction of the ADU or JADU.
2. Unpermitted ADUs constructed before 2018.
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a. Permit to Legalize. As required by state law, the city may not deny a permit to legalize an existing but unpermitted ADU that was constructed before January 1, 2018, if denial is based on either of the following grounds:
(1) The ADU violates applicable building standards, or
(2) The ADU does not comply with the state ADU law (Government Code Section 65852.2) or this ADU ordinance (Chapter 17.52).
b. Exceptions:
(1) Notwithstanding subsection H.2.a. above, the city may deny a permit to legalize an existing but unpermitted ADU that was constructed before January 1, 2018, if the city makes a finding that correcting a violation is necessary to protect the health and safety of the public or of occupants of the structure.
(2) Subsection H.2.a. above does not apply to a building that is deemed to be substandard in accordance with California Health and Safety Code Section 17920.3. (Ord. No. 763, § 3(Exh. A), 1-13-2020; Ord. No. 768, § 3(Exh. A), 3-8-2021; Ord. No. 775, § 3, 11-22-2021; Ord. No. 777, § 3(Exh. A), 12-13-2021; Ord. No. 778, § 3, 12-13-2021; Ord. No. 787, 12-12-2022; Ord. No. 796, § 4(Exh. A), 12-9-2024)
17.52.030 Nonconforming domestic units.
A. All detached domestic units existing as of January 10, 1983, are nonconforming structures. (The term "detached domestic units" means living quarters designed, capable of being used, or intended to be used to house household help, such quarters being not structurally attached to the single-family dwelling served by the household help.) All alterations to or remodeling of nonconforming detached domestic units shall be confined to the interior of such structures; exterior improvements shall be limited to normal upkeep and repair and to such improvements as do not enlarge or alter the existing outside dimensions of the structure.
B. Notwithstanding the foregoing, in the event that a natural disaster (such as fire, earthquake, flood, landslide, etc.) damages or destroys a nonconforming detached domestic unit, the same may be reconstructed to the same or smaller outside dimensions as those of the damaged or destroyed structure.
C. Notwithstanding the foregoing, an existing detached domestic unit that is converted to an ADU may be enlarged to a maximum floor area of one thousand four hundred square feet subject to the requirements of Section 17.52.020.
(Ord. No. 763, § 3(Exh. A), 1-13-2020; Ord. No. 768, § 3(Exh. A), 3-8-2021; Ord. No. 777, § 3(Exh. A), 12-13-2021; Ord. No. 787, 12-12-2022; Ord. No. 796, § 4(Exh. A), 12-9-2024)
17.52.040 Conversion of existing residential space.
Recognizing that there may be a considerable existing stock of potential ADUs in the town and that this stock represents a valuable housing resource for the community, the town wishes to encourage property owners to take advantage of this ADU ordinance. Accordingly, any property owner may apply to the town without penalty or fee for the purpose of converting existing residential space (such as guest suites, guest quarters, pool houses, carriage houses, domestic quarters, etc.) into an ADU in accordance with the provisions and requirements of this chapter. (Ord. No. 763, § 3(Exh. A), 1-13-2020; Ord. No. 768, § 3(Exh. A), 3-8-2021; Ord. No. 777, § 3(Exh. A), 12-13-2021; Ord. No. 787, 12-12-2022; Ord. No. 796, § 4(Exh. A), 12-9-2024) -183-
17.52.050 ADU exception review.
A. An ADU or JADU that does not comply with every applicable standard in Section 17.52.020 may nevertheless be permitted by the director of building and planning, or the director's designee, at the director's or designee's discretion if the ADU or JADU undergoes the design review process set forth in Chapter 2.12 of this code (ADU exemption). An ADU or JADU that does not comply with all the standards in Section 17.52.020 is considered a "type B project" under Section 2.12.070.A.
B. Findings Required. The following findings shall be made in in advance of any approval of an ADU Exception:
1. The project is consistent with the town general plan.
2. The project is consistent with this code, including the town zoning ordinance.
3. The project is consistent with the town residential design guidelines.
4. The project is consistent with all other town land use policies and plans.
5. The project has undergone the design review process outlined in Chapter 2.12 of this code.
6. The project has been publicly noticed as a "type B" project under Section 2.12.070.A of this code.
7. The project does not constitute a risk to the welfare of the town and its residents;
8. The project does not constitute a risk to the health and safety of the town and its residents.
An ADU that complies with all the standards in Section 17.52.020 is approved ministerially in accordance with that section, as indicated by subsection 2.12.070(A)(2)(c)(ix). (Ord. No. 763, § 3(Exh. A), 1-13-2020; Ord. No. 768, § 3(Exh. A), 3-8-2021; Ord. No. 777, § 3(Exh. A), 12-13-2021; Ord. No. 787, 12-12-2022; Ord. No. 796, § 4(Exh. A), 12-9-2024) -184-
TOWN OF HILLSBOROUGH
San Mateo County
1600 Floribunda Avenue
Hillsborough, CA 94010
17 DISCUSSION
CITY COUNCIL MEETING
SEPTEMBER 8, 2025
AGENDA STAFF REPORT
ITEM SUBJECT: UPDATE FROM THE CITY COUNCIL SUBCOMMITTEE FOR THE TOWN
HALL COMPLEX PROJECT
SUMMARY: The staff liaison to the City Council Subcommittee for the Town Hall Complex Project will provide a brief informational update.
FISCAL IMPACT: There is no fiscal impact associated with this agenda item.
ENVIRONMENTAL ISSUES: The proposed action is exempt from environmental review under California Environmental Quality Act (CEQA) Guidelines sections 15378(b)(2) and 15378(b)(5) as ongoing administrative or organizational activities that will not result in direct or indirect physical changes in the environment.
ATTACHMENTS: Unapproved Minutes of the City Council Subcommittee for the Town Hall Complex Project Meeting of August 27, 2025
PREPARED BY: Liz Ruess, Assistant Director of Building & Planning RECOMMENDATION: This is an update only; no City Council action is required. -185-
TOWN OF HILLSBOROUGH
San Mateo County
Leslie Marden Ragsdale, Vice Mayor 1600 Floribunda Avenue Christine Krolik, Councilmember Hillsborough, CA 94010
www.hillsborough.net
Phone 650-375-7400
Unapproved Minutes
AUGUST 27, 2025
2:30 PM
CITY COUNCIL SUBCOMMITTEE FOR
THE TOWN HALL COMPLEX PROJECT
This meeting of the City Council Subcommittee for the Town Hall Complex Project was held in-person in the Administrative Conference Room.
I. CALL TO ORDER
Meeting called to order at 2:30 PM
II. ROLL CALL
Present: Leslie Marden Ragsdale, Christine Krolik
Consultants and Staff Present:
Consultants: Lauren Roan (EHDD) and Karen Curtiss (Red Dot Studio) Staff: Doug Davis (City Manager), Mandy Brown (Assistant City Manager), Tim Anderson (Director of Building & Planning), Liz Ruess (Assistant Director of Building & Planning) III. PUBLIC COMMENT: No speakers.
IV. OLD BUSINESS
1. Assistant Director of Building & Planning Liz Ruess provided an overview of space needs assumptions.
V. NEW BUSINESS
2. Assistant Director of Building & Planning Liz Ruess provided an update regarding revised assumptions and led discussions about site footprint, site adjacencies, Walnut Avenue, and parking.
a. Revised assumption that Central County Fire Dept. (CCFD) will be located off-site due to their need for office space and dedicated parking. The site is unable to meet their requests without impacting Town operations and CCFD has an alternative location nearby in Burlingame.
Subcommittee Direction: Subcommittee confirmed. Would still like to explore the opportunity to have an Emergency Operations Center (EOC) at the Town Hall Complex to be used as training room.
b. Staff confirmed assumption that Town Hall & Police Department (PD) will be new -186-
Unapproved Minutes – City Council Subcommittee for the Town Hall Complex Project Wednesday, August 27, 2025
construction. Renovation of, or addition to existing spaces would limit the development potential of the site due to the current condition of the buildings and building infrastructure (e.g., slab foundation hinders ability to repurpose Town Hall spaces). With the anticipated demand on the site, building new would allow for the most efficient use of space resources to allow for the structures to take advantage of site adjacencies.
Subcommittee Direction: Subcommittee confirmed that new construction should be the assumption for both buildings due to limitations with existing structures and siting. c. Discussion: Site Parking.
The following considerations were discussed:
• The site cannot handle all parking spaces on surface lots. • Acquisition, annexation, and/or rezoning of sites will extend timeline beyond the current RHNA cycle.
• With the revised assumption to not include CCFD in the program, acquisition of neighboring properties is not necessary to accommodate program needs and associated parking, under the condition that podium and/or basement parking will be needed.
• Two-story parking garage is challenging due to site constraints, and it would be difficult to build without the two-story structure being highly visible. • PD would likely have the below-grade secured parking.
Subcommittee Direction: Include up to one-level of below-grade parking in alternatives to consider in order to accommodate the parking needs without creating a visual impact of an above-ground garage. Final recommendation will depend on construction cost, geotechnical analysis to determine soil conditions, and any constructability challenges such as waterproofing.
d. Discussion: Site Adjacencies based on preferred location of PD, housing and community spaces.
Subcommittee Direction: Move as much building frontage of PD as close to El Camino as possible, with additional frontage along the property line shared with the church parcel, to minimize frontage along Floribunda. Subcommittee would like to move forward with two options:
• Option 1 - Housing and its parking on the 1640 Floribunda Ave site/Walnut Lot and the community space located to the east of Walnut Ave, with Town Hall. • Option 2 – Housing is located on the corner of El Camino and Floribunda with the community building located on the 1640 Floribunda Ave site/Walnut Lot. e. Discussion: Relocation of the SFPUC water line.
The relocation of the water line would be costly and likely extend the project timeline beyond the current RHNA cycle. Waiting for more information from SFPUC puts our ability to move forward on hold.
Subcommittee Direction: Treat the SFPUC waterline as a fixed constraint and no longer pursue relocation of the waterline.
f. Discussion: Walnut Avenue realignment.
Depending on site encumbrances, the design could include the realignment of Walnut Avenue, without relocation of the waterline, provided that no structures are built over the line (limited to open space or parking).
Subcommittee Direction: Realigning/Straightening Walnut Avenue would entail costs even without waterline relocation, and given constraints of what could be built over the waterline, this is not worth the effort or expense. The option to cul-de-sac Walnut should -187-
Unapproved Minutes – City Council Subcommittee for the Town Hall Complex Project Wednesday, August 27, 2025
remain under consideration for potential future discussion.
VI. ADJOURNMENT
Meeting adjourned at 3:45 PM
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