Local zoning · Hillsborough

Hillsborough — Land Use

Q: What can I build on an RD‑1 lot in Hillsborough?

You can build a single‑family dwelling and customary accessory structures; ADUs are allowed subject to the ADU chapter; commercial uses are generally prohibited unless specifically permitted (e.g., permitted home businesses under permit). For the precise uses table see § 17.16.010(B) and the home business rules at § 17.16.015 .

Q: What are Hillsborough setback requirements?

The code defines a street‑line setback area (the street‑line setback concept) that is generally a 25‑foot strip measured from the street line; other setback and encroachment rules are in the development standards and in § 17.24.020 . Verify exact front, side, and rear yard numbers in the development standards chapter for your district.

Q: Are ADUs allowed and how are they approved in Hillsborough?

Yes — ADUs and JADUs are permitted in RD‑1, RD‑2, and RD‑3 ; if an ADU meets the ADU chapter standards it is approved ministerially within the statutory timelines; if it does not, it may be allowed via an ADU exception that triggers design review per Chapter 2.12; see § 17.52.020 for the ADU rules and timing.

Q: Can I run a home‑based business from my house?

Possibly, but home businesses must comply with the Town’s permit and operating standards (no outward advertising, no excessive traffic or noise, vehicle restrictions, annual permit) under § 17.16.015 . If you don’t hold the required permit or you exceed the standards, the use is not allowed.

Q: Are commercial cannabis businesses allowed in Hillsborough?

No — all commercial cannabis uses are prohibited in the Town. The code provides a narrow exception allowing deliveries from state‑licensed retailers located outside the Town under conditions; see § 17.65.030 .

Q: What are the rules for two‑unit projects?

Two‑unit projects are governed by Chapter 17.54 : they allow two primary dwelling units under specified rules including owner occupancy (in many cases), separate utility connections, fire‑hazard mitigation if in a high hazard zone, deed restrictions, and prohibition on short‑term rentals; see Chapter 17.54 for details.

Land Use under the Hillsborough local zoning and planning code, with the controlling citations.

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Last reviewed: July 2, 2026

Overview

This page explains what the Hillsborough Zoning Ordinance (Title 17) actually allows and requires for land use in Town — which uses are permitted or require special permits, how the three local residential districts are set up, and the most decision‑relevant rules an applicant needs to check. All requirements below point to the controlling code section (§) in the Hillsborough Municipal Code and to the retrieved ordinance text.

How to read this page

Words you’re likely to check first are in bold (district labels, key numbers).
Where Hillsborough’s rules refer to other topics (parking, setbacks, design review, ADUs, etc.), I link to the corresponding local menu page inline the first time that topic appears so you can jump to details: see the links for parking, development standards, design review, overlay districts, landscaping and screening, nonconforming uses, ADUs, and the California Building Standards Code.

District-by-district breakdown

Note: Hillsborough currently uses three zoning districts for the kinds of properties most readers will face: RD-1, RD-2, and RD-3. The districts are established at § 17.12.010.

RD-1 — Traditional Residential (single‑family)

Purpose: Preserve existing single‑family character; limit density and protect privacy. See § 17.16.010(A)(1).
Typical permitted uses: single‑family dwelling (principal use), accessory structures, family day care home, residential care facilities, town‑owned open space where applicable. These appear as permitted (P) in the uses table at § 17.16.010(B).
Key numeric standards and limits you must check:
- Maximum density: one single‑family dwelling per one‑half acre (exclusive of ADUs) — § 17.16.010(A)(1).
- Setback concept: the street‑line setback area is a 25‑foot strip from the street line unless otherwise stated — § 17.24.020.
- Accessory uses and home businesses: many accessory uses allowed but some require a home business permit and strict limits — see § 17.16.015 and the uses table at § 17.16.010(B).

Where it applies: RD‑1 is the default “traditional residential” classification on the Town zoning map — see the zoning map requirement at § 17.04.030.

RD-2 — Mixed Residential

Purpose: Accommodate townhomes and multifamily on specific town‑owned parcels at higher density — § 17.16.010(A)(2).
Typical permitted uses: multifamily housing (P where shown), public parks, public buildings, telecommunications structures, emergency shelters (allowed by right subject to objective standards), ADUs. See the uses table at § 17.16.010(B).
Key numeric standards:
- Minimum density where applied: 20 units per acre (where RD‑2 is mapped) — § 17.16.010(A)(2).
- Emergency shelters allowed by right in RD‑2 (subject to objective standards listed at § 17.16.010(B)(1)(e) — e.g., up to 3 beds, on‑site parking for staff, intake areas inside the building, on‑site management plan, spacing limits) — see § 17.16.010(B)(1)(e).

Where it applies: only on specific parcels mapped as RD‑2 on the Town zoning map; check the map at Town Hall or the official zoning map filing per § 17.04.030.

RD-3 — Governmental and Residential Mixed Use

Purpose: Accommodate certain town facilities and limited residential units (town‑owned sites), with a maximum of 16 dwelling units where applied — § 17.16.010(A)(3).
Typical permitted uses: town facilities, public buildings, limited multifamily housing, telecommunications structures, public parks, ADUs where applicable — see the uses table at § 17.16.010(B).
Key numerical/operational controls are in the same uses chapter and in the Town’s development standards; check the zoning map and site‑specific constraints.

Most decision‑relevant table (quick reference)

Topic / Use	Allowed in which district(s)	Key local reference
Single‑family dwelling	RD‑1 (P)	§ 17.16.010(A)(1) and § 17.16.010(B)
Accessory dwelling units (ADUs / JADUs)	RD‑1, RD‑2, RD‑3 (P, subject to ADU rules)	§ 17.16.010(B); ADU rules § 17.52.020
Multifamily housing	RD‑2, RD‑3 (P where shown)	§ 17.16.010(B)
Emergency shelters	RD‑2, RD‑3 (P, objective standards)	§ 17.16.010(B)(1)(e)
Private schools	Special permit (S) in residential districts	§ 17.16.010(B)(1)(d)
Home business	Special permit / annual permit; strict limits	§ 17.16.015 and § 17.16.010(B)
Commercial cannabis uses	Prohibited in all districts (deliveries allowed from outside, subject to rules)	§ 17.65.030
Setback / street‑line area	Street‑line setback area defined as 25 ft from the street line	§ 17.24.020

(For ADU ministerial approval timing and other ADU-specific procedural rules see § 17.52.020 and the ADU chapter.)

Practical guidance and synthesis (plain English, but code‑grounded)

RD‑1 is Hillsborough’s single‑family district: if your lot is RD‑1 you can expect primarily single‑family uses, accessory structures, ADUs (subject to the ADU chapter), and tight controls on any business‑like activity (home businesses require permits and strict limits) — see § 17.16.010 and § 17.16.015.
Multifamily and emergency‑shelter allowances are narrowly mapped to RD‑2 and RD‑3 and in most cases are tied to specific town‑owned parcels or special permit rules; don’t assume RD‑2 or RD‑3 is available for private rezoning without a map change — see § 17.16.010(A) and § 17.04.030.
ADUs are permitted across the residential districts and have a ministerial approval pathway if they meet the ADU standards; if an ADU does not meet those standards, an exception can be granted but triggers design review per Chapter 2.12 (see § 17.52.020 and the design‑review cross‑reference).
The Town’s definitions, setback math (the 25‑ft street‑line rule), and accessory‑use rules are critical to site layout. Verify dimensional and coverage numbers in the Town’s development standards chapter before design work — start with § 17.24.020 and the development standards chapter.

First‑time topic links (useful to follow now): parking (/us/california/hillsborough/parking), development standards and setbacks (/us/california/hillsborough/development-standards), design review (/us/california/hillsborough/design-review), overlay districts (/us/california/hillsborough/overlay-districts), landscaping and screening (/us/california/hillsborough/landscaping-and-screening), nonconforming uses (/us/california/hillsborough/nonconforming-uses), ADUs (/us/california/hillsborough/adu), and the California Building Standards Code (/us/california/building-codes).

Checklist (what an applicant must satisfy before filing / to expect)

Confirm district on official zoning map (zoning map requirement: § 17.04.030)
Confirm your proposed use is shown as P (permitted) or S (special permit) in the uses table at § 17.16.010(B) and review the corresponding supplemental standard subsection (a–k) for that use.
Check density rules: RD‑1 = 1 dwelling / ½ acre; RD‑2 = min 20 units/acre where mapped; RD‑3 = max 16 dwellings where mapped — § 17.16.010(A).
Confirm setbacks and street‑line setback (25 ft concept) and other development standards in the development standards chapter and § 17.24.020.
If proposing an ADU, follow § 17.52.020 for ministerial review and timing (60‑day rules) and see ADU-specific notice/permit rules.
If proposing a two‑unit project, follow Chapter 17.54 (owner occupancy, utilities, fire‑hazard mitigation, deed restrictions, no short‑term rentals).
If proposing a private school, film production, fundraising event, or home business, review the special permit and detailed operating standards at § 17.16.010(B)(1) and the related permit sections (e.g., § 17.16.015 for home business).
Check whether the proposal triggers design review (Chapter 2.12) — many nonstandard deviations or ADU exceptions require design review.

Risks & Ambiguities

Issue	Why it matters	What to verify
District boundary / zoning map interpretation	Whether a parcel is RD‑1, RD‑2, or RD‑3 controls permitted uses and density	Verify the parcel’s zone on the Town’s official zoning map per § 17.04.030 and confirm with planning staff.
Exact numeric development standards (height, lot coverage, FAR)	These numbers determine whether a project needs variances or design review	The retrieved materials show setbacks and some accessory structure limits but do not provide a consolidated per‑district table of height, lot coverage, or FAR. Verify with the Town’s development standards chapter and planning staff. (Not found in retrieved materials)
Accessory structure placement that requires adjacent owner consent	Certain small/unenclosed structures require adjoining owner written non‑objection under supplemental use rules	Check the specific supplemental subsection applicable to the accessory structure in § 17.16.010(B)(1)(…) and secure written consents if required.
ADU exceptions vs. ministerial approval	ADUs meeting state/local standards are ministerial; exceptions can trigger discretionary design review and public notice	Confirm which ADU path applies (see § 17.52.020 and design review cross‑referenced in Chapter 2.12).
Two‑unit projects: owner‑occupancy and deed restrictions	Two‑unit projects have owner‑occupancy and deed restriction rules that affect resale and conveyance	Review Chapter 17.54 for deed restriction and occupancy rules and verify whether your lot qualifies (fire, utility connections, nonconforming corrections).
Cannabis use	Commercial cannabis is prohibited — attempting to locate these uses will be denied	§ 17.65.030 prohibits commercial cannabis uses in Town.

Information Gaps (what I could NOT confirm from the retrieved materials)

A district‑by‑district consolidated table of height limits, lot coverage percentages, and FAR for RD‑1 / RD‑2 / RD‑3 (numeric values not found in the retrieved text). Verify in the Town’s development standards chapter or with planning staff. (Not found in retrieved materials)
Exact map locations / parcels currently zoned RD‑2 or RD‑3 — the Code requires a zoning map, but parcel‑level mapping must be checked with Town records. See § 17.04.030.

Plain‑English Summary

Hillsborough’s Title 17 organizes most residential land into RD‑1 (single‑family), RD‑2 (higher‑density/multifamily on specific sites), and RD‑3 (town facilities with limited housing). The uses table in § 17.16.010(B) tells you whether a use is permitted (P), allowed only with a special permit (S), or prohibited; ADUs are allowed in all residential districts but must follow the ADU chapter’s ministerial rules (or go through design review if an exception is requested). Confirm your parcel’s zoning map designation, setbacks (street‑line setback concept is 25 ft), and any special ADU or two‑unit rules before you design — see the cited code sections for each rule.

Source References

Hillsborough Municipal Code, Title 17 — ZONING (print export). Key sections used: § 17.04.030, § 17.12.010, § 17.16.010, § 17.16.015, § 17.24.020, § 17.52.020, Chapter 17.54, § 17.65.030.
ADU ministerial timing and exception rules: § 17.52.020 and ADU chapter text (see ADU approval timelines and exceptions).
Two‑unit projects: Chapter 17.54 (purpose, definitions, application rules, fire‑hazard mitigation, deed restrictions).
Home business rules and operational limits: § 17.16.015 (home business permit and standards).

Sources

Retrieved passages

Hillsborough Zoning Code (§ 2) High relevance
Hillsborough Zoning Code (Chapter 2.12) Medium relevance
Hillsborough Zoning Code (Section 17.08.115) Medium relevance
Hillsborough Zoning Code (Section 17.32.020) Medium relevance
Hillsborough Zoning Code (Title 17) Medium relevance
Hillsborough Zoning Code (Section 17.52.020) Medium relevance
California Fire Code (chapter is) Medium relevance
Hillsborough Zoning Code Medium relevance

Cited sections

Official Hillsborough code library

Frequently asked questions

What can I build on an RD‑1 lot in Hillsborough?

You can build a single‑family dwelling and customary accessory structures; ADUs are allowed subject to the ADU chapter; commercial uses are generally prohibited unless specifically permitted (e.g., permitted home businesses under permit). For the precise uses table see § 17.16.010(B) and the home business rules at § 17.16.015.

What are Hillsborough setback requirements?

The code defines a street‑line setback area (the street‑line setback concept) that is generally a 25‑foot strip measured from the street line; other setback and encroachment rules are in the development standards and in § 17.24.020. Verify exact front, side, and rear yard numbers in the development standards chapter for your district.

Are ADUs allowed and how are they approved in Hillsborough?

Yes — ADUs and JADUs are permitted in RD‑1, RD‑2, and RD‑3; if an ADU meets the ADU chapter standards it is approved ministerially within the statutory timelines; if it does not, it may be allowed via an ADU exception that triggers design review per Chapter 2.12; see § 17.52.020 for the ADU rules and timing.

Do I need design review for changes in Hillsborough?

Some projects — including ADU exceptions, certain new structures higher than local thresholds, and projects tied to variances — are subject to Hillsborough’s design review process (Chapter 2.12). If your project requests exceptions to ADU standards or variances you should expect design review. See the ADU chapter cross‑references and Chapter 2.12.

Can I run a home‑based business from my house?

Possibly, but home businesses must comply with the Town’s permit and operating standards (no outward advertising, no excessive traffic or noise, vehicle restrictions, annual permit) under § 17.16.015. If you don’t hold the required permit or you exceed the standards, the use is not allowed.

Are commercial cannabis businesses allowed in Hillsborough?

No — all commercial cannabis uses are prohibited in the Town. The code provides a narrow exception allowing deliveries from state‑licensed retailers located outside the Town under conditions; see § 17.65.030.

What are the rules for two‑unit projects?

Two‑unit projects are governed by Chapter 17.54: they allow two primary dwelling units under specified rules including owner occupancy (in many cases), separate utility connections, fire‑hazard mitigation if in a high hazard zone, deed restrictions, and prohibition on short‑term rentals; see Chapter 17.54 for details.

When is a private school allowed in a residential district?

Private schools are listed as allowed only with a special permit (S) in the uses table; they also must meet the permit and supplemental standards called out at § 17.16.010(B)(1)(d) and related permit sections.

If my lot is RD‑2 can I build single‑family homes instead of multifamily?

RD‑2 is intended to permit townhomes and multifamily at higher density (minimum density rules apply where mapped). Whether a single‑family design is acceptable depends on the parcel’s mapped use and applicable density requirements in § 17.16.010(A)(2); check the official zoning map and discuss with planning staff.

What happens if my existing structure doesn’t meet current zoning?

Nonconforming conditions are addressed by the code; specific rules apply to legal nonconforming uses listed in Title 17 and other chapters. For ADUs, the Town will generally not deny an ADU solely because of a nonconforming condition that does not threaten health and safety (ADU chapter). See the nonconforming‑uses provisions and § 17.52.020(H) for ADU‑related nonconforming guidance.

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