Hidden Hills — Development Standards

Last reviewed: July 2, 2026

Overview

This page summarizes what the Hidden Hills zoning ordinance requires for development standards (setbacks, height, lot coverage, density/FAR and related controls) and how those rules vary by zone. The City’s local development rules are codified in the Zoning provisions (see Hidden Hills Zoning) and are applied together with the Hidden Hills Community Association architectural standards and applicable state law (for example ADU rules and the California Building Standards Code). Key local rules cited below are drawn directly from the City code: minimum lot sizes and coverage in the RA‑S rules, R‑1 dimensional controls, special ADU rules, and architectural/site plan review standards; citations to the controlling code sections are provided inline.

District-by-district breakdown

Below are the districts and the Hidden Hills code provisions that control what you can build. Each district subsection gives the purpose/typical uses, then the most decision-relevant numeric standards and the controlling code citation.

RA‑S (Rural/Agricultural — RA‑S)

• Purpose / typical uses
  The RA‑S zone is the large‑lot residential/agricultural zone intended to preserve rural character and low density; typical permitted development is a single‑family residence with accessory buildings and equestrian/stable uses. See the code’s list of allowed accessory uses for the zone. § 5‑2C (permitting and definitions) .

• Key dimensional & development standards (plain English)

  • Minimum lot area: 1 acre (net) (§ 5‑2C‑2(A)) .
  • Maximum lot/building coverage: 25% of the net lot area (coverage excludes roof overhangs) (§ 5‑2C‑2(C)) .
  • Front setback: 50 ft (§ 5‑2C‑4 — Front Yard Setback language) .
  • Side setback: 15 ft minimum from easement line or 25 ft from side lot line (corner lots have special measurement rules) (§ 5‑2C‑4(B)) .
  • Rear setback: 50 ft rear yard; within the rear yard there is a required setback area of 25 ft from the rear lot line or 15 ft from an easement line, whichever is greater (§ 5‑2C‑4(C)) .
  • Heights: RA‑S uses a height envelope and cap based on roof‑ridge distance to the front lot line; example caps include roof ridge limits of 26–28 ft with building caps up to 30–32 ft depending on ridge location (§ 5‑2C‑3(A)(1–3)) .
  • Second‑floor ratio / massing: Where applicable, second‑story floor area must be limited and massed toward the rear (see second‑story rules adopted throughout residential articles; applicable cross‑refs apply) (§ 5‑2C & related sections) .

• Where it applies: large lots and much of the City; RA‑S‑2 is a close variation (see below). See §§ 5‑2C and 5‑2D.

RA‑S‑2 (Large‑lot variant — RA‑S‑2)

• Purpose / typical uses
  A close variant of RA‑S intended to carry most RA‑S rules but with local differences for specific parcels.

• Key dimensional summary
  The RA‑S‑2 Zone “shall meet all requirements of the RA‑S Zone, including but not limited to requirements to lot area per dwelling, lot coverage, front yards, side yards, rear yards, lot widths, distance between buildings, pedestrianways, cornices and eaves, uncovered porches and platforms, barbed wire fences, lighting of tennis courts, height of fences, garages, paved driveways and outdoor lighting fixtures” (§ 5‑2D‑3). In short: apply RA‑S standards unless a discrete RA‑S‑2 text modifies them. § 5‑2D‑3 .

• ADU note: the code allows optional larger ADU size specifically in RA‑S‑2 (see ADU rules below) (§ 5‑2P‑7(A)(4)) .

R‑1 (Single‑Family Residential — R‑1)

• Purpose / typical uses
  The R‑1 zone is for single‑family residences and incidental accessory uses (private garage, playhouses, private recreational facilities, ADUs/JADUs subject to Article P). § 5‑2E‑1 lists permitted uses. .

• Key dimensional & development standards

  • Minimum lot area: 20,000 sq ft (§ 5‑2E‑2(A)) .
  • Maximum lot/building coverage: 30% of lot area (includes accessory buildings; area beneath roof overhangs counted) (§ 5‑2E‑2(C)) .
  • Front setback: 35 ft (§ 5‑2E‑4(A)) .
  • Side setbacks: 25 ft when abutting RA‑S; 5 ft when abutting another R‑1 or commercial designation (§ 5‑2E‑4(B)) .
  • Rear setbacks: 25 ft when abutting RA‑S; 15 ft when abutting R‑1; 5 ft when abutting commercial (§ 5‑2E‑4(C)) .
  • Height / second‑story rules: R‑1 height is tied to RA‑S envelope/cap and the second floor may not exceed 50% of the first‑floor footprint; second‑story massing must be toward the rear (§ 5‑2E‑3(A–C)) .

• Practical note: these dimensional setbacks explicitly prohibit most accessory structures in front yards (§ 5‑2E‑4(A)) .

Commercial / Commercial‑Restricted (Commercial Zone)

• Purpose / typical uses
  Small pockets of commercial activity are regulated so commercial architecture reflects the City’s residential character; architectural/site plan review is mandatory. § 5‑2F‑6 addresses permitted uses and standards. .

• Key dimensional / special standards

  • Architectural/site plan review required for any building, sign, wall, fence, or landscaping (§ 5‑2F‑6) .
  • The Planning Agency may, as an incentive under architectural/site plan review, authorize a Floor Area Ratio (FAR) up to 1.2:1 and may reduce required yards provided yards abutting residential property remain at least 10 ft (§ 5‑2F‑6(C)) .
  • The Agency’s findings for such incentives emphasize open space, concealed parking, superior architectural design and mature landscaping (§ 5‑2F‑6(C)(1–5)) .

Important cross‑cutting rules and programs

• Objective SB9 standards: The ordinance contains an Article O with objective standards for projects under Senate Bill 9; it treats RA‑S, RA‑S‑2, and R‑1 as “single‑family residential zones” for SB9 purposes and lists objective limits and prohibitions (no ridgeline development, grading limits, tree/dripline protections, septic/percolation test rules) (§ 5‑2O‑1 through § 5‑2O‑3). .

• ADU rules (Article P): Hidden Hills adopts local ADU standards that implement state ADU law but also add zone‑specific objective standards. Notable local ADU rules: maximum unit sizes, second‑floor ratios, 4‑ft side and rear setbacks for ADUs, a 50‑ft front setback in certain ADU subsections, and that an ADU may not cause total lot coverage to exceed 25% for certain ADU classes (§ 5‑2P‑7 and § 5‑2P‑6). See Article P for the full matrix of ADU classes and exemptions; the code also ties local ADU allowance to state ADU rules. § 5‑2P‑7; § 5‑2P‑6 .

• Architectural and Site Plan Review: Most projects require architectural and site plan review; the Planning Director/Planning Agency apply findings about neighborhood compatibility, contour following, preservation of native vegetation, and conformity with the General Plan. There are exemptions for small remodels (see Planning Director exemption thresholds) (§ 5‑2H and the relevant site plan review article) .

• Minor structures, projections, fences, and lighting: The code specifies how porches, eaves, cornices, AC equipment, minor structures, perimeter fences, and outdoor lighting are handled, including numeric projection limits and maximum lighting intensities (§ 5‑2C‑5 and related subsections) .

• Incentives and density bonus flexibility: The City’s density‑bonus / incentives article allows reductions or modifications to standards (setbacks, lot coverage, height, parking) for qualifying affordable housing projects; the City may not impose standards that physically preclude permitted densities (§ 5‑2M‑4, § 5‑2M‑5) .

Quick reference table — decision‑relevant standards

Checklist

An applicant should confirm and include the following when preparing a submittal:

• Confirm zoning district and applicable standards (RA‑S / RA‑S‑2 / R‑1 / Commercial) — cite the applicable § (e.g., § 5‑2C‑2, § 5‑2E‑2) .
• Demonstrate compliance with setbacks, lot coverage, and height limits from the applicable zone (§ 5‑2C‑2–4, § 5‑2E‑2–4) .
• Provide site plan and elevations for Architectural & Site Plan Review (or confirm exemption thresholds) (§ 5‑2H, § 5‑2F‑6) .
• If proposing ADU(s), follow Article P ADU standards (unit size limits, setbacks, lot coverage caps for ADUs) and state ADU rules; provide ADU plan and compliance narrative (§ 5‑2P‑6; § 5‑2P‑7) .
• Confirm whether Hidden Hills Community Association architectural approval or certification is required and include any written certification if relying on the Association’s approval as an exemption or to support Planning Director findings (§ 5‑2H, SB9 Article) .
• Provide documentation to show compliance with Fire Code / water supply/fire flow requirements and, if on septic, a recent percolation test where required (§ 5‑2O‑3(3,13)) .
• Address lighting, fences, and minor structures with the numeric rules in § 5‑2C‑5 (lighting caps, fence rules, projections) .
• If seeking incentives (e.g., increased FAR, reduced setbacks), include the required findings and design justification per the density/incentives articles (§ 5‑2M & § 5‑2F‑6(C)) .
• Coordinate off‑street parking requirements (see municipal parking rules) and demonstrate how parking will be concealed or sited if requesting FAR or yard reductions (parking may be allowed in setbacks for ADUs under specific conditions) — see Parking rules and ADU parking exceptions. Link to the City parking guidance: Hidden Hills Parking. .

Risks & Ambiguities

Plain‑English Summary

Hidden Hills’ zoning rules keep the city low‑density and rural: RA‑S lots are typically 1 acre with 50 ft front yards and 25% lot coverage, R‑1 lots are smaller (20,000 sq ft) with 35 ft front yards and 30% coverage, ADUs are allowed but must meet Article P’s size, setback and lot coverage rules, and most changes are subject to architectural/site plan review — confirm all numeric limits in the ordinance for your parcel before design. Key local citations: §§ 5‑2C, 5‑2D, 5‑2E, 5‑2P, 5‑2F.

Source References

• Hidden Hills Zoning Ordinance — RA‑S lot and coverage rules: § 5‑2C‑2; building height envelope: § 5‑2C‑3.
• Hidden Hills Zoning Ordinance — RA‑S setbacks and related yard rules: § 5‑2C‑4.
• Hidden Hills Zoning Ordinance — R‑1 permitted uses, lot size, coverage, height and yards: § 5‑2E‑1, § 5‑2E‑2, § 5‑2E‑3, § 5‑2E‑4.
• Hidden Hills Zoning Ordinance — RA‑S‑2 relationship to RA‑S: § 5‑2D‑3.
• Hidden Hills Zoning Ordinance — Architectural & Site Plan Review; Commercial incentives (including FAR up to 1.2:1): § 5‑2F‑6.
• Hidden Hills Zoning Ordinance — ADU rules (Article P): § 5‑2P‑6; § 5‑2P‑7 (unit sizes, setbacks, lot coverage for ADUs).
• Hidden Hills Zoning Ordinance — SB9 objective standards and restrictions (Article O): § 5‑2O‑1 to § 5‑2O‑3 (ridgeline prohibition, grading limits, percolation test).
• Hidden Hills Zoning Ordinance — Minor structures, projections, and outdoor lighting rules: § 5‑2C‑5.
• Hidden Hills Zoning Ordinance — Incentives and density bonus program: § 5‑2M.
• State / implementation references used by the local ADU text: California ADU handbook excerpts included in the files for context (state ADU law and constraints on local standards).

Retrieved passages

• Hidden Hills Zoning Code (Title and) High relevance show source text
• CBC § 66314 (§ 66314) High relevance show source text
• CFC § 5 (ARTICLE O.) High relevance show source text
• CFC § 65852.21 (Article is) High relevance show source text
• Hidden Hills Zoning Code (section 5-2P-7) High relevance show source text
• Hidden Hills Zoning Code (§ 5) High relevance show source text
• Hidden Hills Zoning Code High relevance show source text
• Hidden Hills Zoning Code (Section prior) Medium relevance show source text
• Hidden Hills Zoning Code (§ 3) High relevance show source text
• Hidden Hills Zoning Code (§ 11) Medium relevance show source text
• Hidden Hills Zoning Code (Section as) Medium relevance show source text
• Hidden Hills Zoning Code (Section as) Medium relevance show source text

Cited sections

• Hidden Hills Zoning Ordinance — RA‑S lot and coverage rules: **§ 5‑2C‑2**; building height envelope: **§ 5‑2C‑3**. (§ 5)
• Hidden Hills Zoning Ordinance — RA‑S setbacks and related yard rules: **§ 5‑2C‑4**. (§ 5)
• Hidden Hills Zoning Ordinance — R‑1 permitted uses, lot size, coverage, height and yards: **§ 5‑2E‑1**, **§ 5‑2E‑2**, **§ 5‑2E‑3**, **§ 5‑2E‑4**. fileciteturn1file17turn0file5turn0file5turn1file6 (§ 5)
• Hidden Hills Zoning Ordinance — RA‑S‑2 relationship to RA‑S: **§ 5‑2D‑3**. (§ 5)
• Hidden Hills Zoning Ordinance — Architectural & Site Plan Review; Commercial incentives (including FAR up to 1.2:1): **§ 5‑2F‑6**. (§ 5)
• Hidden Hills Zoning Ordinance — ADU rules (Article P): **§ 5‑2P‑6**; **§ 5‑2P‑7** (unit sizes, setbacks, lot coverage for ADUs). fileciteturn1file8turn1file1 (Article P)
• Hidden Hills Zoning Ordinance — SB9 objective standards and restrictions (Article O): **§ 5‑2O‑1 to § 5‑2O‑3** (ridgeline prohibition, grading limits, percolation test). (Article O)
• Hidden Hills Zoning Ordinance — Minor structures, projections, and outdoor lighting rules: **§ 5‑2C‑5**. (§ 5)
• Hidden Hills Zoning Ordinance — Incentives and density bonus program: **§ 5‑2M**. (§ 5)
• State / implementation references used by the local ADU text: California ADU handbook excerpts included in the files for context (state ADU law and constraints on local standards). fileciteturn1file2turn1file15
• HiddenHills_ZoningCode.md

• Official Hidden Hills code library