Local zoning · San Mateo County

San Mateo County — Land Use

Land Use under the San Mateo County local zoning and planning code, with the controlling citations.

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Last reviewed: July 3, 2026

Overview

San Mateo County’s land-use rules for unincorporated areas are codified in the County Zoning and Development Code (Title 8 of the County Ordinance Code). The code organizes permitted versus conditionally permitted activities by zoning district (e.g., R‑E, R‑H, RM, C‑1, C‑2, MH, A‑2, TPZ‑CZ, RM‑CZ, plus site‑specific PUD and SS districts), and adds programmatic rules for special areas (Coastal Zone, Planned Agricultural Districts, Scenic Corridors, Resource Management). Find basic navigation to the County’s zoning rules via the San Mateo County Zoning page.

This page summarizes what the ordinance says about what uses are allowed where in the County’s unincorporated areas, the most decision‑relevant dimensional and use standards, and practical checks applicants must satisfy. All standards described below come from the County Zoning and Development Code; every requirement is tied to the controlling § cited inline.

How the Code treats uses (quick rules)

  • Uses listed as “permitted” in a district may proceed subject to development standards for that district; uses listed as requiring a “use permit” are discretionary and decided under § 8.280.010 (Use Permits) and related hearing/notice rules.
  • Many areas (Coastal Zone, RM‑CZ, TPZ‑CZ, PAD) carry supplemental resource, hazard, or public‑access standards that either limit or require additional approvals; see the district sections below for the controlling § citations.
  • Accessory Dwelling Units (ADUs) are addressed by a discrete ADU chapter and are allowed in residential and many mixed districts; ministerial approval rules and ADU development standards are in § 8.392 and the Coastal ADU chapter § 8.396.
  • For district development rules such as setbacks, heights, lot coverage and lot area, consult each district chapter and the County’s Development Standards.

Also note: parking requirements are separate and enforced via the County’s parking chapter; check the County parking rules for stall counts and design.

District-by-district summary (where the code is explicit)

Below are the most commonly used unincorporated district rules and where they apply. For every district I list (1) purpose, (2) typical permitted uses and conditional uses, (3) key dimensional standards the ordinance explicitly calls out, and (4) where that district is applied or special notes. All items are grounded in the County Zoning and Development Code (Title 8) and cite the controlling §.

R‑E (Residential Estates) — § 8.12.010–.030

  • Purpose: Single‑family estate living with limited accessory agricultural uses. § 8.12.010.
  • Typical permitted uses: one‑family dwellings, public parks/playgrounds, crop and tree farming, home occupations, accessory buildings (e.g., servants’ quarters), nurseries (non‑retail). § 8.12.020.
  • Conditional/limited uses: schools, churches, fire stations, golf courses, additional residences tied to agricultural operation (via use permit). § 8.12.020.
  • Dimensional highlights: second dwelling units are governed by Chapter § 8.392 (ADU/second unit rules). § 8.12.030.
  • Where applied: larger estate parcels in the unincorporated County; see zoning maps and parcel records. Verify parcel‑specific application with the County.

RH (Residential Hillside) — § 8.110.010 (chapter header)

  • Purpose: Allow single‑family dwellings in hillside contexts, protect natural topography and scenic character. § 8.110.010.
  • Uses: Primarily one‑family dwellings and accessory structures; limited institutional/recreational uses compatible with residential hillside character. § 8.110.010.
  • Dimensional emphasis: design/site planning to preserve vegetation, minimize grading — specifics are in the RH chapter and the general development standards. § 8.110.010.
  • Note: ADUs are explicitly allowed in RH subject to ADU chapter rules. § 8.392.

RM / RM‑CZ (Multiple‑Family / Resource Management — Coastal Zone) — §§ 8.138., 8.294. file

  • Purpose: The RM‑CZ (Resource Management‑Coastal Zone) combines resource protection with allowed forms of development where appropriate; RM generally covers multi‑family residential and compatible uses. § 8.138.020 and related RM‑CZ chapters.
  • Typical uses: multi‑family dwellings, limited commercial/visitor‑serving uses in specified circumstances. RM‑CZ adds public access, shoreline dedication, and CEQA‑level development review rules for ANY development. § 8.294.010–.040.
  • Dimensional/permit highlights: All development in RM‑CZ requires a Development Review Permit and must meet RM‑CZ environmental and shoreline criteria; some setbacks/density are district‑specific in the RM chapter. § 8.138.040 and § 8.294.020–.040. file

C‑1 (Neighborhood Business) — § 8.68.010–.020; C‑2 (General Commercial) — § 8.76.010–.020 file

  • Purpose: C‑1 supports neighborhood services; C‑2 allows broader commercial activities including small industry and repair uses. § 8.68.010, § 8.76.010. file
  • Typical permitted uses:
    • C‑1: bakeries, banks, barber/beauty shops, drugstores, small retail, auto service stations (limited), nursing/clinic uses require a use permit. § 8.68.020.
    • C‑2: all C‑1 uses plus repair garages, lumber yards, laundries, bowling alleys, etc.; residential uses typically require a use permit. § 8.76.020.
  • Dimensional examples (C‑1/C‑2): front yard, side and rear yard minima and maximum height are set either by the district chapter or by combined “S” overlay requirements; C‑1 side yard = 5 ft, rear = 20 ft, front & street side variable by map or S‑district; maximum height commonly 36 ft for mixed structures in certain PUDs (see PUD examples). § 8.68.030; see PUD entries for site‑specific height limits. file
  • Note: Uses that would normally be prohibited in other districts may be allowed in some circumstances by use permit; see § 8.280.010 for the standards for issuing use permits.

O (Office) — § 8.64.010–.030

  • Purpose: Professional and medical office uses, while retaining compatibility with adjacent residential districts. § 8.64.010.
  • Uses: Offices, medical/dental clinics (some require use permit), and multi‑family dwellings in some cases. § 8.64.020.
  • Development standards: setback, height, lot coverage generally follow the combined “S” district or map‑specific requirements; no mixed residential/non‑residential use in the same building unless permitted. § 8.64.030.

A‑2 (Exclusive Agriculture District) — § 8.40.010–.020 and PAD rules in § 8.106.* file

  • Purpose: Protect agricultural production (cropland, tree crops) and allow only compatible uses. § 8.40.010 and Planned Agricultural District (PAD) rules § 8.106. file
  • Typical permitted uses: agricultural production and accessory farm uses; residences are allowed only as accessory or via PAD/permitted farm labor housing. § 8.40.020, § 8.106.040. file
  • Special rules: PAD requires Planned Agricultural Permits for many non‑agricultural uses and imposes easement/deed notice and agricultural land management plan requirements. § 8.106.040–.170.

MH (Mobilehome Park) — § 8.260.040–.050

  • Purpose: Regulate creation/operation of mobilehome parks including resident services and park facilities. § 8.260.040.
  • Permitted uses: mobilehome parks (subject to a Mobilehome Park Permit); accessory commercial uses serving park residents (grocery, managers’ office, laundry) typically require a use permit. § 8.260.040.
  • Note: Park creation/major changes require specific park permits and compliance with park standards in the chapter. § 8.260.050.

TPZ‑CZ (Timberland Preserve — Coastal Zone) — Chapter 8.318 (TPZ‑CZ)

  • Purpose: Limit development to timber production and compatible uses; major developments require a Development & Timber Management (DTM) Plan. § 8.318.010–.080.
  • Uses: Timber harvesting (per the Timber Harvesting Ordinance, Chapter 8.408), limited compatible uses; minor vs major development thresholds are defined and trigger different approval paths. § 8.318.020–.050.

PUD (Planned Unit Development) and SS (Special/Specific Site) districts — Chapter 8.273 et seq.; examples PUD‑119+, PUD‑134, PUD‑138, SS‑101 etc. file

  • Purpose: Site‑specific development rules for parcels where the PUD/SS ordinance sets a bespoke program. § 8.273.020 and individual PUD ordinances. file
  • Uses and standards: PUDs list precise permitted uses, employee limits, parking counts, setbacks, height, signage and hours of operation. Examples: PUD‑134 restricts uses to a specific office program and parking (see PUD text). PUDs are controlling for their parcels (their own sections supersede other Title 8 provisions where they conflict). file
  • Practical consequence: If your parcel is in a PUD or SS district, read that PUD’s ordinance — it can drastically change permitted uses and dimensional standards.

Quick Comparison Table — decision‑relevant uses and standards

District Typical permitted uses (decision focus) Key dimensional / control points Code reference
R‑E One‑family dwellings, accessory agriculture, nurseries (no retail) Second units governed by ADU chapter; lot/use limits in chapter § 8.12.020, § 8.12.030
RH Single‑family hillside dwellings; accessory Slope/landscape protection, design review emphasis (see RH chapter) § 8.110.010
RM / RM‑CZ Multi‑family, limited visitor uses (CZ adds public access rules) All development in RM‑CZ requires Development Review Permit and CEQA compliance § 8.138.040, § 8.294.020 file
C‑1 Neighborhood retail & services (banks, drugstore, barber) Side yard 5 ft, rear yard 20 ft; some uses require use permit § 8.68.020–.030
C‑2 Broader commercial: repair, laundries, lumber yards, etc. Residential uses need use permit; signage/parking rules apply § 8.76.020
A‑2 / PAD Agricultural production; farm labor housing per permit PAD requires Planned Agricultural Permit; conversion controls & deed notices § 8.40.020, § 8.106.040 file
MH Mobilehome parks (park permit required), accessory resident services Mobilehome Park Permit and use‑permit requirements for some activities § 8.260.040–.050
TPZ‑CZ Timber, compatible uses, DTM plans for major development Development and Timber Management Plan required for major development § 8.318.010–.080
PUD / SS Parcel‑specific uses (see the PUD ordinance text) PUD-specific setbacks/heights/parking often controlling Chapter 8.273 / individual PUD ordinances file

Key procedural rules that affect whether a use is allowed

  • Use permits: The County may issue use permits for uses identified in Title 8; the general rule for when a use permit may be issued is in § 8.280.010 (lists types of uses and the findings required).
  • Coastal Zone: Uses and permits inside the Coastal Zone must also comply with LCP policies and Coastal Development Permit procedures (hearing, notice, appeals) — see Coastal Zone chapters (e.g., § 8.252 and RM‑CZ additions). Noting: use permits in the Coastal Zone have extra findings. § 8.280.010 and Coastal sections. file
  • Historic uses: Uses not normally allowed may be permitted in historic structures/districts if the Planning Commission finds the use compatible; see Historic Resources chapter and § 8.280.010(g) for the process.
  • ADUs: Accessory dwelling unit approvals are ministerial where they meet the objective standards of the ADU chapter (§ 8.392) and the Coastal ADU chapter (§ 8.396) when in the Coastal Zone; otherwise they may require a conditional use permit. See the County ADU rules and also state ADU law. California ADU law.

Note on development standards: Where the district or PUD does not state a precise number for a setback, height, lot coverage or parking, the general development provisions and overlay S‑district specifications apply — check the combined “S” district and the Development Standards chapter.

Checklist — what an applicant must confirm before filing

  • Identify the parcel’s exact zoning and any overlay or PUD/SS district designations (verify via County zoning map and file a zoning verification). (See Chapter 8.273 and parcel PUD language.)
  • Confirm whether the proposed use is listed as permitted or requires a use permit; if discretionary, plan for the findings in § 8.280.010.
  • Check Coastal Zone, RM‑CZ, TPZ‑CZ, PAD or Scenic Corridor rules that add findings or require DTM/Development Review permits and CEQA compliance. § 8.318, § 8.138, § 8.106, § 8.292. filefile
  • Confirm parking counts and design per the County parking chapter. See the parking rules.
  • Confirm setback, height, lot coverage and landscape/screening requirements in the district chapter and in Development Standards.
  • If the parcel is in a PUD/SS district, read that PUD/SS ordinance carefully — it may supersede general district rules. (See PUD examples in Chapter 8.273.)
  • For ADUs, use the ADU chapter standards (ministerial approval if objective standards are met) and check the Coastal ADU exceptions in § 8.396. California ADU law and § 8.392/ § 8.396.
  • If your use may affect historic resources, consult the Historic Resources Advisory Board rules and the Historic chapter for required findings.
  • Be prepared to provide required technical studies where indicated (e.g., DTM for TPZ‑CZ, biological reports in RM‑CZ, geotechnical slopes in RH). § 8.318, § 8.292, § 8.110. filefile

Also plan early contact with the County on design review triggers (see the County Design Review page) and for site‑specific interpretation of combined “S” overlay standards.

Risks & Ambiguities

Issue Why it matters What to verify
PUD / SS parcel controls A PUD ordinance can override general district rules and impose unique limits on use, hours, employees, signage, parking. Confirm whether your lot is within a PUD or SS and read the parcel’s PUD/SS ordinance (Chapter 8.273) — PUD text is controlling. file
Coastal Zone / RM‑CZ findings Extra findings, public access and CEQA requirements can add time and conditions. If parcel is in Coastal Zone or RM‑CZ, confirm needed Coastal Development Permits and Development Review (see § 8.294, § 8.252). file
Agricultural easements / PAD restrictions Easements or PAD covenants can prohibit non‑ag uses or require clustering. Check recorded easements and PAD permit history; PAD uses are governed by § 8.106.
Nonconforming situations Existing legal uses/structures may be nonconforming and entitlements to expand or change are limited. Check Non‑Conforming definitions and allowable changes in Title 8 (nonconforming parcel/use/structure rules). Verify with the County.
Parking and signage Commercial uses often trigger substantial parking and signage standards not spelled out in the district chapter. Confirm parking counts and signage allowances early — see the County parking chapter and sign rules (referenced in PUDs and C‑districts). file
ADU coastal exceptions ADU ministerial approval is limited in the Coastal Zone — Coastal ADU chapter adds rules. If parcel is in Coastal Zone, read § 8.396 and the ADU chapter § 8.392. Verify with County staff.

Plain‑English summary

In unincorporated San Mateo County, what you can build is determined by the parcel’s zoning district (e.g., residential, commercial, agricultural, timber), and many sensitive or special areas (Coastal Zone, PAD, TPZ‑CZ, RM‑CZ, PUDs) add extra findings or bespoke rules; uses that aren’t listed as “permitted” require a use permit under § 8.280.010, and many dimensional rules and parking requirements are spelled out either in each district chapter or in site‑specific PUD ordinances — verify your parcel’s zone and any PUD/overlay before you design. file

Source References

  • Use permit and general use permit rules: § 8.280.010.
  • ADU chapter and ministerial ADU standards: § 8.392; Coastal ADU chapter § 8.396.
  • R‑E district permitted uses and second‑unit reference: § 8.12.020–.030.
  • RH district purpose and hillside protections: § 8.110.010.
  • RM‑CZ district and development‑review requirements: § 8.138.020, § 8.294.010–.040. file
  • C‑1 neighborhood business permitted uses and yards: § 8.68.020–.030.
  • C‑2 general commercial uses: § 8.76.020.
  • O (Office) district development standards: § 8.64.020–.030.
  • A‑2 / PAD agricultural rules and Planned Agricultural Permit uses: § 8.40.020, § 8.106.040–.170. file
  • MH (Mobilehome) district uses and park permit notes: § 8.260.040–.050.
  • TPZ‑CZ Timberland Coastal Zone development plan/DTM requirements: § 8.318.010–.080.
  • PUD / Special Site ordinances and examples: Chapter 8.273 and specific PUD entries (e.g., PUD‑134, PUD‑138). file
  • County Development Standards (for district dimensional rules and combined “S” overlays): Title 8 development standards chapters.

For general navigation to the County zoning materials use: San Mateo County Zoning & Planning overview. (/us/california/san-mateo-county) and the San Mateo County Zoning page. (/us/california/san-mateo-county/zoning)

Sources

Retrieved passages

  • San Mateo County Zoning Code (CHAPTER 8.280) High relevance
  • San Mateo County Zoning Code (section for) High relevance
  • San Mateo County Zoning Code (Title 8) High relevance
  • San Mateo County Zoning Code (Title 8) High relevance
  • San Mateo County Zoning Code (Title 8) High relevance
  • San Mateo County Zoning Code (SECTION H.) High relevance
  • San Mateo County Zoning Code (section should) High relevance
  • San Mateo County Zoning Code (Title 8) High relevance
  • San Mateo County Zoning Code (Section 8.344.030) High relevance
  • San Mateo County Zoning Code (Title 8) Medium relevance
  • San Mateo County Zoning Code (chapter is) Medium relevance
  • San Mateo County Zoning Code (Title 8) Medium relevance
  • San Mateo County Zoning Code (Chapter 8.384) Medium relevance
  • San Mateo County Zoning Code (Article 2) Medium relevance

Cited sections

Frequently asked questions

What can I build on an R‑1 lot in San Mateo County?

The basic R‑1 (single‑family) district permits one‑family dwellings and accessory buildings; specific dimensional standards (setbacks, height, lot coverage) are set in the R‑1 chapter or by any combined “S” overlay that applies to the parcel. Verify the parcel’s map designation—if your parcel is subject to a PUD, PAD or Coastal overlay those rules also control. (See related district chapters and the County development standards.)

What are San Mateo County setback requirements for commercial lots?

Setback minima are listed in each commercial district chapter. For example, C‑1 districts specify typical side and rear yards (side 5 ft, rear 20 ft) and front yard requirements are set by map or combined “S” district rules; always confirm the applicable S‑overlay or map note for your parcel because the zoning map can change front‑yard requirements. § 8.68.030.

Do I need a use permit to open a business in the County’s C‑1 or C‑2 districts?

Some businesses are permitted outright; many activities (hospitals, large institutions, hotels, some residential uses in commercial districts) require a use permit under § 8.280.010, which triggers discretionary review and required findings. Check the specific list of allowed and conditional uses in § 8.68 for C‑1 and § 8.76 for C‑2 to determine if your business needs a use permit. file

Can I build an ADU on my unincorporated San Mateo County lot?

Yes, ADUs are allowed in R‑1, R‑2, R‑3, RH, RM, TPZ and other districts where residential uses are permitted. ADUs that meet the ADU chapter’s objective standards are approved ministerially under § 8.392; Coastal ADU rules are in § 8.396 and may affect review procedures in the Coastal Zone. Check both County ADU chapters and any Coastal overlay.

What is a PUD and why does it matter for allowed uses?

A PUD (Planned Unit Development) is a parcel‑specific ordinance that lists permitted uses, limits (height, parking, employees, hours) and unique site requirements; where a PUD exists it can supersede general district rules for that parcel, so always read the PUD ordinance text excerpted in Chapter 8.273 for your APN. file

Do Coastal Zone parcels have different land‑use rules?

Yes. Parcels in the Coastal Zone (and RM‑CZ parcels) require Coastal consistency with the Local Coastal Program, extra findings for use permits, and certain public‑access or environmental requirements; developments there commonly require Coastal Development Permits and the RM‑CZ Development Review process in § 8.294. file

Are agricultural parcels allowed non‑farm uses?

Agricultural zoning (A‑2 and PAD) is protective of farming. PAD allows agricultural uses and only limited compatible non‑ag uses by Planned Agricultural Permit; conversions and additional residences are tightly controlled and may require deed notices and findings § 8.106. Check recorded easements before assuming non‑ag use is possible.

If my existing use doesn’t match the zoning, can I expand it?

If the use is a legal nonconforming use, expansion is limited by the nonconforming provisions; the County defines nonconforming parcel/structure/use rules and allowable repair/alteration thresholds. Verify the nonconforming status and permitted changes under the nonconforming rules in Title 8.

Does the County require design review for new development?

Many areas require design review — check the County’s design review rules and district chapters. Where design review applies it is handled under the County’s design review process (see the County Design Review guidance) and may be triggered by PUD conditions or Coastal/Scenic Corridor rules. file

Where do I find parking requirements for a proposed use?

Parking counts and design are established in the County parking chapter; PUDs and district chapters (C‑ and RM‑districts) also reference parking standards and may include minimum numbers (some PUDs list precise counts). Check the County parking chapter and the PUD/district text for parcel‑specific requirements. file ---

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