Hidden Hills Zoning, Planning & Building Codes

Last reviewed: July 3, 2026

Overview

Hidden Hills codifies land-use and development rules in Title 5 — Land Use and Development (the City's zoning and development regulations) under the municipal code; the Title sets purpose, definitions, zone creation authority and cross‑references State planning law (§ 5-1-1, § 5-2A-1). The City’s zoning map establishes six primary local zone designations (three residential/estate types, two commercial/community types, plus an affordable‑housing overlay) and a set of implementing articles that contain development standards, site/design review rules, and special overlays (§ 5-2B-2).

This page explains how the Hidden Hills code is organized, the actual district names and where to find the controlling numeric standards (§ citations), the citywide rules that commonly matter to owners and developers (setbacks, height, FAR, parking), design and site‑plan review, key overlays and specific‑plan style programs (notably the Affordable Housing Overlay), the building‑permit path, and how State housing laws (ADU, SB 9, density bonus) have been incorporated into the local code.

(Links: first mention of topics below — zoning, development standards, parking, design review, overlay districts, ADUs, California Building Standards Code, California ADU law.)

• For the City’s base zoning menu see Hidden Hills Zoning (/us/california/hidden-hills/zoning).
• For the City’s numeric site standards see Hidden Hills Development Standards (/us/california/hidden-hills/development-standards).
• For parking rules see Hidden Hills Parking (/us/california/hidden-hills/parking).
• For the local design and architectural review path see Hidden Hills Design Review (/us/california/hidden-hills/design-review).
• For overlays (including the affordable‑housing overlay) see Hidden Hills Overlay Districts (/us/california/hidden-hills/overlay-districts).
• For accessory dwelling unit rules see Hidden Hills ADUs (/us/california/hidden-hills/adu).
• The City adopts the State building code by reference; see California Building Standards Code (/us/california/building-codes).
• How State ADU rules interact with local law is tied to California ADU law (/us/california/california-adu-laws).

---

How Hidden Hills's code is organized

• The City’s zoning and development regulations live in Title 5 — Land Use and Development (chapter and article structure). The Title opens with purpose/definitions and then divides into CHAPTER 2 — ZONING (Articles A, B, C, etc.) and separate Articles for site plan review, special programs, and administrative provisions (e.g., Articles F, H, M, O, P). See § 5‑1‑1 and § 5‑2A‑1 for scope and authority.
• Zoning chapters are arranged by Article: Article B establishes the zones (§ 5‑2B‑2); Articles C/E/F/G set out zone‑specific development and yard rules for RA‑S, RA‑S‑2, R‑1, C‑R, C‑U and overlays; Article H is the City’s site plan / neighborhood compatibility rules (site plan review) (§ 5‑2H‑1 through § 5‑2H‑4).
• The code adopts State law and standard definitions by reference (Zoning Act, Map Act) so readers must read local numeric rules alongside the State statutory framework (§ 5‑2A‑2).

Use the Table of Contents in Title 5 (Chapter headings) to jump to: zoning districts (Article B), development standards by zone (Articles C, E, F), site plan review (Article H), density bonus (Article M), the SB 9/urban lot split rules (Article O), and the ADU rules (Article P).

---

Zoning district families (actual local districts)

Hidden Hills establishes six local zone designations (exact text in the code):

• RA‑S (Residential Agriculture Suburban) — large‑lot/estate residential standards and setbacks (§ 5‑2C‑4).
• RA‑S‑2 (Residential Agriculture Suburban‑2) — a second estate/residential variant listed in the zones table (§ 5‑2B‑2).
• R‑1 (Residential) — the single‑family residential district with its own yard, height and second‑story massing limits (§ 5‑2E‑3, § 5‑2E‑4).
• C‑R (Commercial‑Restricted) — allows limited commercial and professional uses and contains special development standards and the Affordable Housing Overlay (AHO) designation (§ 5‑2F‑1, § 5‑2F‑5).
• C‑U (Community Uses) — for public and quasi‑public uses (see Article G for rules) (§ 5‑2G‑1).
• AH‑O / AHO (Affordable Housing Overlay) — a zoning overlay placed within the CR zone to allow and require lower‑income multiple‑family dwellings on specific parcels, with minimum density and affordability and site‑plan requirements (§ 5‑2F‑9).

Each district’s permitted, conditional and prohibited uses are listed in the corresponding Article (e.g., permitted uses in the CR zone are in § 5‑2F‑1).

---

Citywide development standards (high level — where the rules live)

Hidden Hills keeps most numeric development rules inside the Articles for each zone and in the ADU and density bonus Articles; the code also has cross‑cutting chapters (e.g., Landscape, Parking, Floodplain). Key, enforceable points:

• Building‑height and second‑story massing:

  • Height envelopes and a two‑story cap are applied in several zones; for example, the CR zone sets a 30‑foot envelope and no more than two stories unless approved by the Planning Agency in Architectural and Site Plan Review (§ 5‑2F‑5:C).
  • R‑1 inherits height envelope limits from RA‑S and limits second‑story area to 50% of the first‑story footprint (§ 5‑2E‑3:B).

• Setbacks / yards:

  • RA‑S: typical front yard 50 ft, side yard 15–25 ft depending on measuring line, rear yard 50 ft (§ 5‑2C‑4).
  • R‑1: typical front yard 35 ft, side yards 25 ft (if abutting RA‑S) or 5 ft (if abutting R‑1), rear yard 15–25 ft depending on abutting zone (§ 5‑2E‑4).
  • CR: common yard minima are 25 ft front/side/rear, with masonry walls required when abutting residential property (§ 5‑2F‑5:D–E).

• Lot coverage / FAR:

  • CR sets a base FAR = 1.0 and the Planning Agency may authorize up to 1.2:1 FAR as an incentive when design criteria are met (§ 5‑2F‑5:A; § 5‑2F‑6:C).

• Parking:

  • Nonresidential parking ratios and bicycle parking rules are spelled out in the CR development standards and in the parking chapter; typical retail ratio is 1 space / 250 sq ft, professional offices 1 / 300 sq ft, with additional bicycle and vanpool rules for large‑scale projects (§ 5‑2F‑5:G; parking chapter cross‑references). See Hidden Hills Parking for the subject menu.

• Projections, minor structures, fences and lighting:

  • Eaves, cornices and mechanical equipment may encroach up to 4 ft into setback; porches may project up to 10 ft; perimeter fences are allowed but subject to Community Association approval and city standards (§ 5‑2C‑5:F–H).

Where to read these numbers: check the Article for the zone that applies to a parcel (e.g., RA‑S rules at § 5‑2C‑4; R‑1 rules at § 5‑2E‑4; CR development standards at § 5‑2F‑5).

---

Specific plans & overlays

• Affordable Housing Overlay (AHO): created as § 5‑2F‑9 — the AHO sits inside the CR zone, requires a minimum density of 20 units/acre on AHO parcels, a minimum project size (16 units), affordability covenants or agreements (30 years for rentals), and site plan review by the Planning Agency (§ 5‑2F‑9:D–F).
• Density Bonus program: the City implements State density bonus law as Article M (5‑2M‑1 et seq.); it describes the percent density increases, allowable incentives, and process for granting bonuses (§ 5‑2M‑1 through § 5‑2M‑8).
• SB 9 / urban lot splits: Hidden Hills adopted a local SB 9 implementation (Article O). SB 9‑type lot splits and ministerial approvals are handled through zoning clearance and a recorded covenant with specific occupancy and affordability/short‑term‑rental restrictions; the local ministerial review rules are in § 5‑2O‑6 and related subsections (Article O).
• Other overlays and special chapters: the City includes a Wireless Facilities Chapter, Floodplain controls, Landscaping / Water Efficient Landscape rules, and Historic/Community Association review touchpoints — see respective Articles in Title 5 (e.g., wireless § 5‑13‑5/7, floodplain Chapter 9).

For more detail on overlays and the parcels where they apply see Hidden Hills Overlay Districts. (/us/california/hidden-hills/overlay-districts)

---

Building permits & review — the practical path

• Applicability and building code: the City enforces the California Building Code by reference as the local Technical Codes (2025 CBC adopted by reference) and requires compliance with the Building, Plumbing, Mechanical, Electrical and Housing Codes before permits can be issued (§ 5‑5B‑1; general enforcement provisions in Chapter 5).
• Design / site plan review:
  • Most residential additions, new structures and nearly all commercial projects require site plan review / architectural and site plan review under Article H (site plan review) or zone‑specific Article F (Architectural and Site Plan Review required in the CR zone § 5‑2F‑6). The code lists findings, application materials, concept review, notice, and public hearing requirements (§ 5‑2H‑4 and § 5‑2F‑6).
  • The Planning Director conducts initial checklists, and smaller projects may be exempt — for example the Planning Director can certify exemptions for projects below numeric thresholds (e.g., additions ≤ 500 sq ft; total structure ≤ 1,000 sq ft) in the site plan article (§ 5‑2H‑4:E).
• Administrative vs discretionary approvals:
  • Routine permits and ministerial approvals (e.g., building permits that are consistent with the zoning and conforming site plan) proceed through the Building Official and permit counter; discretionary approvals (site plan review, conditional use permits, variances) go to the Planning Agency or City Council depending on the procedure (§ 5‑2H and related articles).
• Special ministerial paths:
  • SB 9 lot splits and SB 9‑compliant unit approvals are processed ministerially through a zoning clearance with recordation requirements and ministerial denial standards listed in § 5‑2O‑6 (no hearing, final Planning Director decision unless a denial finding is made) (§ 5‑2O‑6).
• Approvals and conditions:
  • Planning Agency approvals may carry conditions, incentives (e.g., higher FAR up to 1.2:1 under design criteria), and recorded affordability agreements as conditions of building permit issuance (§ 5‑2F‑6:C; § 5‑2M series).

In practice: start with zoning verification (identify applicable Article in Title 5), then pre‑app / concept review where available, then prepare the Architectural/Site Plan submittal per the City’s checklist, and be prepared for agency and (for some projects) Planning Agency hearings (§ 5‑2H‑4:D).

---

State housing law in Hidden Hills

Hidden Hills expressly integrates State housing law into local rules. Below are the main intersections and where to read them in the local code.

Accessory Dwelling Units (ADUs & JADUs)

• Local ADU rules are in Article P — Accessory Dwelling Units (§ 5‑2P‑1 et seq.). The code organizes ADUs into classes (Class 1 statutorily regulated and Class 2 locally regulated) and adopts State size/ setback/height permissive rules consistent with Government Code requirements; it also sets local details like parking, utility connections, owner‑occupancy (State limits owner‑occupancy restrictions), and permitting procedures (§ 5‑2P‑5—5‑2P‑9).
• Specifics in Hidden Hills:
  • Detached ADU base height 16 ft (with 18 ft or 20 ft exceptions consistent with state distances/conditions) and attached ADU height limited to 25 ft or the underlying zone limit, not to exceed two stories where applicable (§ 5‑2P‑6:B).
  • ADUs must meet 4‑ft side and rear setbacks for limited detached ADUs; ADUs can count tandem or setback parking and sometimes are exempt from parking — see § 5‑2P‑7 (parking rules and exemptions).
  • The City will not deny an ADU permit based on certain nonconforming conditions or pre‑2020 unpermitted ADUs per State law (see § 5‑2P‑9).

(See Hidden Hills ADUs for the City’s local ADU menu and the cross‑references to State law.) (/us/california/hidden-hills/adu)

SB 9 (ministerial duplex + urban lot split)

• Hidden Hills adopted local SB 9 implementation in Article O. SB 9 applications that meet the Article’s standards are processed ministerially via zoning clearance; applicants must execute a recorded covenant with occupancy/short‑term rental and other restrictions (see the covenant list in Article O) and the Planning Director’s ministerial denial criteria are narrow (§ 5‑2O‑6 and related subsections).

Density bonus and incentives

• The City’s density bonus program (Article M, § 5‑2M‑1 et seq.) implements State density bonus law: it enumerates the percentage increases for low/very low income and the number and types of incentives a qualifying project may request, and prescribes an administrative process for approving density bonus requests as part of site‑plan/permit processing. The City also ties incentives to specific findings and affordability agreements (§ 5‑2M series).

Rent control / tenant protections

• Hidden Hills does not operate a local rent‑control regime in Title 5. For ADUs there is an explicit minimum rental term of 30 days for ADUs/JADUs in Article P (§ 5‑2P‑6:D). Broader rent control would normally be in another Title or ordinance; verify with the City Attorney and Municipal Code outside Title 5 if you need further confirmation.

---

Practical orientation — common developer / owner questions (short checklist)

• Determine zoning: identify parcel zone in the Official Zoning Map and read the corresponding Article (e.g., RA‑S rules at § 5‑2C‑4; R‑1 rules at § 5‑2E‑4; CR at § 5‑2F‑1 & § 5‑2F‑5).
• Check whether site plan review or architectural/site plan review is required: Article H (§ 5‑2H‑4) governs residential site plan review; the CR zone requires Architectural and Site Plan Review under § 5‑2F‑6.
• For ADUs start at Article P (§ 5‑2P‑1—5‑2P‑9) to confirm class, setbacks, parking and whether the project qualifies for ministerial approval.
• For SB 9 / urban lot splits review Article O — ministerial zoning clearance and the covenant/recordation requirements are mandatory (§ 5‑2O‑6).
• For building permits the City enforces the California Building Code as adopted locally (§ 5‑5B‑1) — plan review and Building Official sign‑offs are required before final permits/COs.

---

Source References

• Hidden Hills Municipal Code — Title 5, Land Use and Development (Full text / table of contents; see purpose/definitions at § 5‑1‑1 / § 5‑2A‑1)
• Zoning districts and map; zones established (RA‑S, RA‑S‑2, R‑1, C‑R, C‑U, AH‑O) — § 5‑2B‑2.
• RA‑S yard rules — § 5‑2C‑4 (front/side/rear yards and projections).
• R‑1 yards / height / massing — § 5‑2E‑3 and § 5‑2E‑4.
• Commercial‑Restricted zone development standards and Architectural & Site Plan Review — § 5‑2F‑5 and § 5‑2F‑6.
• Affordable Housing Overlay — § 5‑2F‑9 (definition, density, affordability, site plan requirements).
• Site Plan Review (residential) — Article H, § 5‑2H‑1 and § 5‑2H‑4 (procedures, exemptions, findings).
• Accessory Dwelling Units (ADUs / JADUs) — Article P, § 5‑2P‑1 through § 5‑2P‑9 (classes, setbacks, heights, parking, legalization of unpermitted ADUs).
• SB 9 / Urban Lot Split rules — Article O, including ministerial review and covenant requirements (§ 5‑2O‑6 and related text).
• California Building Code adoption (local adoption by reference) — § 5‑5B‑1.

(If you need the full printed code or direct Municode links for a particular §, I can fetch the exact Municode URL for specific sections and paste it into the Source References list.)