Local zoning · Monte Sereno

Monte Sereno — Zoning

Zoning under the Monte Sereno local zoning and planning code, with the controlling citations.

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Last reviewed: July 2, 2026

Overview

Monte Sereno's zoning rules are codified in the city's municipal zoning ordinance (Title 10 of the City code) and implement the city's map-based districting plan. The ordinance establishes residential districts (R‑1‑44, R‑1‑20, R‑1‑8, RM), public districts (P, P/RM), and a Planned Development (PD) overlay, sets dimensional limits (setbacks, coverage, maximum building area), and identifies which uses are allowed by right or by permit. The official zoning map is adopted and kept on file with the City Clerk (§ 10.04.020) .

This page focuses strictly on what the Monte Sereno ordinance says about zoning (districts, uses, dimensional and special development standards, cluster and PD rules) and points to related procedural topics where required (for process, see the design review and development standards pages).

How Monte Sereno organizes zoning (quick legal anchors)

  • Zoning districts established: R‑1‑44, R‑1‑20, R‑1‑8, RM, P, P/RM, and PD (§ 10.05.010) .
  • The official zoning map is part of the code and may be amended by ordinance (§ 10.04.020) .
  • Where boundaries are unclear the map rules in § 10.04.030 control (follow lot lines, street centerlines, or scale; appeals to City Council) (§ 10.04.030) .

District-by-district breakdown

R‑1‑44 (Residential — 43,560 sq ft and up)

Purpose: Preserves very low‑density, large‑lot, rural/residential character (§ 10.05.020) .

Typical permitted uses:

  • One single‑family dwelling per lot, accessory buildings, horticulture, limited small animals, up to four household pets, home occupations, renting of rooms (with kitchen limits), accessory dwelling units (ADUs), junior ADUs (§ 10.05.020 A) .

Uses requiring a use permit:

  • Public schools, churches, community centers, public recreation, etc. (§ 10.05.020 B) .

Key dimensional/other standards:

  • Maximum building area caps for the R‑1‑44 district: 6,150 sq ft as the baseline maximum building area (subject to slope adjustments and garage rules) (see building area rules) (ordinance text for building area limits) .
  • Site development permit triggers include large additions and second‑story additions; see § 10.08.040 .

Where it applies:

  • All lots mapped as R‑1‑44 on the adopted zoning map (official map on file, § 10.04.020) .

R‑1‑20 (Residential — ~20,000 sq ft)

Purpose: Medium‑large residential lots intended to preserve low density while allowing larger homes (§ 10.05.030) .

Typical permitted uses:

  • Single‑family dwelling, accessory buildings, horticulture, limited small animals, pets, home occupations, ADUs, JADUs (§ 10.05.030 A) .

Key dimensional standards (high‑value numbers to decide a project):

  • Minimum lot area: 21,780 sq ft (or slope density formula) and 100 ft frontage (§ 10.05.030 C.1) .
  • Front setback: 30 ft (single‑story) / 40 ft (second story) (§ 10.05.030 C.2) .
  • Side interior setbacks: 15 ft (single‑story) / 20 ft (second story); accessory structures 6 ft (§ 10.05.030 C.3) .
  • Rear setback: 30 ft (single‑story) / 40 ft (second story) (§ 10.05.030 C.4) .
  • Maximum building area (district cap): 4,500 sq ft baseline, subject to slope adjustments; see building area rules .
  • Maximum structural coverage/impervious coverage rules apply across residential districts (e.g., base structural coverage 30%, impervious 40% with reductions for larger lots and slopes) (§ 10.05.* coverage rules) .

Where it applies:

  • Lots shown as R‑1‑20 on the official zoning map (§ 10.04.020) .

R‑1‑8 (Residential — ~8,000 sq ft)

Purpose: Higher‑density single‑family lots within the city's residential pattern (§ 10.05.040) .

Typical permitted uses:

  • One single‑family dwelling per lot, accessory buildings, horticulture, limited animals, home occupations, ADUs, JADUs, and certain residential care/supportive housing (§ 10.05.040 A) .

Key dimensional standards:

  • Minimum lot area: 8,000 sq ft (or slope density formula); minimum lot frontage 70 ft (§ 10.05.040 C.1) .
  • Front setback: 25 ft (single‑story) / 30 ft (second story) (§ 10.05.040 C.2) .
  • Side setbacks: 6 ft (single‑story) / 10 ft (second story); corner side setbacks larger (see § 10.05.040 C.3 and 3.1) .
  • Rear setback: 30 ft for both single and second story portions in many cases (§ 10.05.040 C.4) .
  • Maximum building area cap for R‑1‑8: 2,850 sq ft baseline (subject to slope rules) .
  • Structural and impervious coverage limits described in the residential standards apply (see coverage rules) .

Where it applies:

  • As shown on the official zoning map (§ 10.04.020) .

RM (Residential Multi‑Family) — RM / RM(PD) (14,520 sq ft min)

Purpose: Allows small multi‑family (duplex/triplex) or clustered residential units while protecting neighborhood character (§ 10.05.043) .

Typical permitted uses:

  • Single‑family, duplex, or triplex per lot; accessory buildings (limited), ADUs and JADUs where the lot is residential; home occupations; residential care/supportive housing (§ 10.05.043 A & B) .

Key dimensional standards:

  • Minimum net lot size per unit: 14,520 sq ft or slope density formula (§ 10.05.043 C.1) .
  • Front setback: 25 ft (single‑story) / 30 ft (second story) (§ 10.05.043 C.2) .
  • Side setback: 6 ft (single‑story) / 10 ft (second story); corner side setbacks larger (§ 10.05.043 C.3 & 3.1) .
  • RM has explicit development standards for unit spacing and lot size; cluster rules may allow alternative configurations under § 10.05.050 (cluster housing) .

Where it applies:

  • Mapped RM parcels on the official map (§ 10.04.020) .

P (Public) and P/RM (Public/Residential Multi‑Family)

Purpose: Public uses (parks, public facilities) and mixed zones where public/residential multi‑family uses are intended (§ 10.05.010) .

Uses and standards:

  • P: public buildings, facilities; development standards referenced to minimum lot sizes set in § 10.05.010. P/RM allows combined public/residential uses and is subject to RM development rules where residential uses occur (§ 10.05.010) .

PD (Planned Development) overlay

Purpose: Allows site‑specific, custom zoning for larger residential projects (PD must be combined with a base residential district; PD applied to parcels of at least 4 acres) (§ 10.05.010, 10.05.047) .

What to expect:

  • A PD is effectuated only by an adopted PD permit/general development plan; until a PD is implemented the base district rules apply (§ 10.05.047 B) .
  • Once implemented, the PD controls every detail (height, floor area, parking numbers) and supersedes base district standards (§ 10.05.047 B.3) .

Citywide standards that matter for every district (quick reference)

  • Official zoning map and boundary interpretation: § 10.04.020 and § 10.04.030 .
  • Site development permit triggers (new main house; additions above certain sizes; roof height increases; second‑story additions): § 10.08.040 .
  • Design review requirement: All structures are subject to design review per Chapter 8 and § 10.05.046; planned development and site development permit applications have detailed submittal content requirements (§ 10.05.046; § 10.08.050; § 10.08.130) .
  • Maximum building area caps by district: R‑1‑8 = 2,850 sq ft; R‑1‑20 = 4,500 sq ft; R‑1‑44 = 6,150 sq ft (subject to slope reductions and garage allowances) (ordinance building‑area rules) .
  • Structural coverage and impervious coverage formulas and tiered reductions for larger lots/slopes are in the residential development standards (coverage caps ~30% structural; ~40% impervious as baseline with reductions) (§ 10.05.* coverage provisions) .
  • ADU rules: ADUs are permitted in all residential districts and are subject to the ADU standards (sizes and parking rules are spelled out in § 10.06.140) — see the dedicated ADUs page for interpretation; the ordinance allows R‑1‑8/R‑1‑20 ADU up to 850–1,000 sq ft and R‑1‑44 up to 1,200 sq ft with parking exceptions listed (§ 10.06.140) .
  • Off‑street parking requirements and guest parking for cluster developments and PDs are spelled out in the ordinance; refer to the city's parking rules (§ 10.05 cluster/PD parking rules) and see the city's parking page for process guidance (§ 10.05 cluster and PD sections) .
  • Cluster development: special density formula and standards are in § 10.05.050 (minimum site area, unit density formula, minimum distances, parking, open space) .

Decision‑relevant table (quick look)

Item Rule / Typical Value Code Reference
Official zoning map Adopted and kept on file; Council can amend map by ordinance § 10.04.020
R‑1‑8 min lot / frontage 8,000 sq ft / 70 ft § 10.05.040 C.1
R‑1‑20 min lot / frontage 21,780 sq ft / 100 ft § 10.05.030 C.1
R‑1‑44 min lot 43,560 sq ft § 10.05.010
RM min net lot per unit 14,520 sq ft (or slope formula) § 10.05.043 C.1
Max building area (district caps) R‑1‑8: 2,850 / R‑1‑20: 4,500 / R‑1‑44: 6,150 (sq ft, slope adjustments apply) Building area rules in ordinance (see building area provisions)
Structural coverage baseline 30% (adjustments for large lots/slopes) Coverage rules (residential standards) (coverage table)
Site development permit triggers New main house; additions above prescribed SF; second story additions; roof height increases § 10.08.040
ADU maximum sizes R‑1‑8 / R‑1‑20: 850 or 1,000 (multi‑bed) ; R‑1‑44: 1,200 § 10.06.140
PD special rule PD controls exact heights, floor area, parking when implemented; PD applies only when PD permit effectuated § 10.05.047

Checklist

  • Confirm official zoning for the parcel with the City Clerk / official zoning map (§ 10.04.020) .
  • Identify base district (R‑1‑8 / R‑1‑20 / R‑1‑44 / RM / P / P/RM / PD) and check permitted uses (§ 10.05.010; district sections) .
  • Calculate lot‑based dimensional limits (minimum lot area/frontage; front/side/rear setbacks) per district (§ 10.05.040; § 10.05.030; § 10.05.020) .
  • Check maximum building area cap for the district and slope adjustments (building area rules) .
  • Determine if project triggers a site development permit or PD permit or design review (§ 10.08.040; § 10.05.046; § 10.05.047) .
  • For ADUs: confirm allowed size and parking exceptions under § 10.06.140 and related ADU rules; see ADUs for guidance (§ 10.06.140) .
  • Check coverage (structural / impervious) and any conservation or scenic corridor overlays that add constraints (§ 10.05.* coverage rules; § 10.05.060) .
  • For any boundary or rule ambiguity, be ready to request map interpretation or use the variance/appeal processes (boundary rules § 10.04.030; variance language in floodplain and variance sections) .

Risks & Ambiguities

Issue Why it matters What to verify
Zoning boundary uncertainty Ordinance interprets map edges by lot lines/streets or scale; misreading changes allowed uses and setbacks Verify official map with City Clerk; use § 10.04.030 for interpretation and appeal options
PD supersedes base district A PD, once effectuated, replaces base district rules for that parcel (height, parking, areas) — projects approved under PD follow the PD permit, not base code Confirm whether a PD permit was implemented for the parcel (see § 10.05.047)
Lot area vs. slope density Building area/lot size and setbacks can change under the slope density formulas (reductions/increases apply) Check slope calculations, applicable Subdivision Chapter slope density formula and the building area rules (district caps)
ADU parking and size exceptions ADU sizes and parking exemptions are tightly specified; local ADU rules may interact with state law Verify ADU sizing and parking exceptions under § 10.06.140 and reconcile with state ADU law; see ADUs
Cluster development density math Cluster density uses a specific formula — mistakes change permitted unit counts When pursuing cluster housing, run the X = site area/(L + 2,100) formula and confirm L via slope formula in § 10.05.050

Plain‑English summary

Monte Sereno divides the city into a few residential districts (big‑lot R‑1‑44, mid‑lot R‑1‑20, small‑lot R‑1‑8), an RM multi‑family district, and public/PD designations; each district lists what you can build by right (single‑family, accessory structures, ADUs are permitted across residential zones) and sets concrete yard/setback, coverage, and maximum building area limits — check the official zoning map and the district rules before you design, because PDs and cluster rules can change the specifics (§ 10.05.010; § 10.04.020; district sections) .

Source References

  • Official zoning map and interpretation: § 10.04.020, § 10.04.030 .
  • Zoning district list and PD rules: § 10.05.010; Planned Development § 10.05.047 .
  • R‑1‑44 district uses: § 10.05.020 .
  • R‑1‑20 district uses & development standards: § 10.05.030 (development standards and setbacks) .
  • R‑1‑8 district uses & development standards: § 10.05.040 (setbacks, lot frontage) .
  • RM (Multi‑Family) uses & standards: § 10.05.043 .
  • Site development permits / triggers: § 10.08.040 and permit process § 10.08.050 / § 10.08.130 .
  • Cluster development rules: § 10.05.050 and associated standards (density formula, parking, spacing) .
  • Residential building area & coverage caps and adjustments: ordinance building area and coverage rules (district caps) (building area rules) .
  • ADU standards and parking exceptions: § 10.06.140 (ADU sizes, parking) .
  • Design review requirement: § 10.05.046; Site and Architectural Commission/submission requirements are in Chapter 8 and permit process sections .

Sources

Retrieved passages

  • Monte Sereno Zoning Code (§ 1) High relevance
  • Monte Sereno Zoning Code (§ 1) High relevance
  • Monte Sereno Zoning Code (Section 10.21.150) High relevance
  • Monte Sereno Zoning Code (§1) High relevance
  • Monte Sereno Zoning Code (Chapter 5) High relevance
  • Monte Sereno Zoning Code (Section 65801) High relevance
  • Monte Sereno Zoning Code (Section 10.21.160.) Medium relevance
  • Monte Sereno Zoning Code (§ 2) Medium relevance
  • Monte Sereno Zoning Code (§ 3) High relevance
  • Monte Sereno Zoning Code (Chapter including) High relevance
  • Monte Sereno Zoning Code (Section shall) High relevance
  • Monte Sereno Zoning Code (Chapter 10.05) High relevance
  • Monte Sereno Zoning Code (Chapter 10.08) High relevance
  • Monte Sereno Zoning Code (Chapter 10.05) High relevance
  • Monte Sereno Zoning Code (Section the) High relevance
  • Monte Sereno Zoning Code (§ 4) High relevance
  • Monte Sereno Zoning Code (Chapter and) High relevance
  • Monte Sereno Zoning Code (§ 4) High relevance
  • Monte Sereno Zoning Code (Chapter pertaining) High relevance

Cited sections

Frequently asked questions

What can I build on an R‑1‑8 lot in Monte Sereno?

You can build one single‑family dwelling with accessory buildings/structures, horticulture, limited household animals, home occupations, and ADUs/JADUs permitted by the ordinance; certain institutional uses (schools, churches, community centers) require a use permit. See § 10.05.040 for permitted uses and § 10.05.040 C for setbacks and lot frontage rules .

What are Monte Sereno's setback requirements for R‑1‑20?

Minimum setbacks in R‑1‑20 are 30 ft front for single‑story, 40 ft for second‑story portions; side interior setbacks 15 ft (single) / 20 ft (second); rear 30 ft (single) / 40 ft (second). These are in the district's development standards under § 10.05.030 C .

Do I need design review in Monte Sereno?

Yes — the ordinance states that all structures are subject to design review in accordance with Chapter 8; many projects (new main houses, large additions, second stories) also require a site development permit handled through the Site and Architectural Commission (§ 10.05.046; § 10.08.040) .

How big can my house be under each residential district?

The ordinance sets maximum baseline building area caps: R‑1‑8 = 2,850 sq ft; R‑1‑20 = 4,500 sq ft; R‑1‑44 = 6,150 sq ft, subject to slope adjustments and garage allowances; see the building area provisions in the ordinance for calculation details and exceptions .

Are ADUs allowed and do they need parking?

ADUs are permitted in all residential districts. Maximum ADU sizes are set in the ADU section (for example R‑1‑8/R‑1‑20: 850 sq ft or 1,000 sq ft if multi‑bed; R‑1‑44: 1,200 sq ft) and parking is required in many cases but several exemptions apply (within 1/2 mile of transit, part of existing dwelling, etc.) — see § 10.06.140 for full rules .

What is a Planned Development and how does it change rules for a parcel?

A PD is a site‑specific zoning overlay adopted by ordinance with an attached general development plan; until a PD permit is implemented the base district rules apply. Once implemented the PD's permit controls exact heights, floor areas, parking numbers and locations, and other specifications (PD supersedes base code for that parcel) — see § 10.05.047 .

Can I cluster smaller lots to increase units on a site?

Yes, cluster development is allowed in R‑1‑8, RM and P/RM subject to § 10.05.050 (minimum site area, density formula, unit spacing, parking and open space requirements). The ordinance requires a specific density calculation and Council approval for cluster proposals .

How do I determine which district a parcel is in if the map is unclear?

The ordinance provides rules for interpreting a boundary — follow street/alley right‑of‑way lines or lot lines where indicated, use map scale where unsubdivided property is involved, and appeal interpretation to the City Council if necessary under § 10.04.030 .

Does Monte Sereno allow commercial cannabis uses?

No — the ordinance expressly prohibits commercial cannabis activities in all zoning districts; limited indoor personal cultivation is allowed under strict limits (§ 10.26.020) .

Where do I confirm parking counts for a PD or cluster project?

A PD must specify the exact number of off‑street parking spaces in the PD permit; cluster developments and PDs have parking requirements in the cluster/PD chapters and the ordinance's parking provisions — see § 10.05.047 B.3(c) and cluster parking rules (§ 10.05.050 and implementing sections) and consult the city's parking page for procedural guidance .

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