Diamond Bar — Zoning

Last reviewed: July 2, 2026

Overview

This page explains how Diamond Bar regulates zoning through its Title 22 - Development Code (the city's zoning & planning overview). It summarizes the official zoning districts, how the zoning map is adopted and interpreted, and the most decision-relevant development rules in the Code. For related topics referenced below see the city's pages on Land Use, Development Standards, Parking, Design Review, Overlay Districts, and ADUs. Building-permit technical rules remain in the California Building Standards Code (Title 24).

Base authorities and mapping

• Diamond Bar's zoning districts are established by § 22.06.020 (Title 22, Table 2‑1) — the official district list and symbols (e.g., RR, RL, RM, C‑2, C‑3, OP, I, AG, OS, REC, PD, C‑3‑PD/Hotel, etc.) are adopted there.
• The City Council adopted the official City of Diamond Bar Zoning Map (on file with the department); the map (boundaries, legends, overlays) is incorporated by reference into Title 22 and is interpreted per map‑boundary rules. See § 22.06.030.
• Which uses are allowed in each district, and whether they are Permitted (P), Minor Use Permit (MUP), or Conditional Use Permit (CUP), are defined by the use tables and the rules in § 22.06.040(c) (Tables 2‑3, 2‑5, 2‑6, 2‑8).

District-by-district breakdown

Below are the Code's district names, the stated purpose(s), typical allowed uses as described in the Code, and the explicit numeric standards the Development Code provides. Where specific numeric rules were not found in the retrieved materials, I call that out and tell you where to verify.

Important note: permitted uses and permit levels are listed in the Code's use tables referenced by § 22.06.040(c); always check the table that applies to the specific parcel.

RR (Rural Residential)

• Purpose: Applied to low-density/rural residential areas when annexed; implements Rural Residential general plan category. § 22.06.020.
• Typical uses: single‑family dwellings and accessory residential uses (per residential chapters). Verify allowable accessory and density rules in the Residential Chapter. § 22.06.020.
• Key standards: Minimum lot/density specifics are not listed for RR in the retrieved excerpts — Verify with the City (see § 22.08 residential district standards; not found in retrieved materials).

RL (Low Density Residential)

• Purpose: Implements Low Density Residential general plan category. § 22.06.020.
• Typical uses: single‑family homes, accessory uses, ADUs per ADU section. See § 22.42.120 for ADU rules.
• Key standards: Specific front/side/rear setbacks, lot coverage, and height for RL are in the residential standards chapter (refer to Article II / Chapter 22.08); numeric values were not present in the retrieved snippets — Verify with the City.

RLM (Low/Medium Density Residential), RM (Medium Density), RMH (Medium/High Density), RI‑1 (High Density), RH‑30 (High Density — 30 units/acre)

• Purpose: Incremental residential density districts implementing the general plan density categories. § 22.06.020. RH‑30 explicitly implements a 30 dwelling units/acre standard.
• Typical uses: multifamily residential types where allowed; multifamily is explicitly permitted in the housing overlay and RH‑30 rules apply there. § 22.14.050(d) references applying RH‑30 standards to certain overlay sites.
• Key standards: RH‑30: 30 units/acre (Table 2‑1). For other residential districts, consult Chapter 22.08 for density, setbacks and coverage. Not all numeric setbacks/lot sizes were in retrieved excerpts — Verify with the City.

OP, OB, CO, C‑1, C‑2, C‑3 (Office / Commercial)

• Purpose: Districts for office, business park, commercial office, neighborhood to regional commercial uses. § 22.10.020.
• Typical uses: offices, retail, services; scale increases from C‑1 (neighborhood) up to C‑3 (regional). See the use tables referenced in § 22.06.040(c) for permitted vs. conditional uses.
• Key standards: For nonresidential development in OP, OB, CO, C‑1, C‑2, C‑3 the allowable floor area ratio (FAR) is 0.25 to 1.00 (stated in the Code for each of these districts). § 22.10.020.

I (Light Industry)

• Purpose: Applied where light industrial uses are appropriate. § 22.06.020 and the commercial/industrial chapter.
• Typical uses: manufacturing, light industrial, warehousing compatible with the Code’s definitions. Check use tables for permit levels. § 22.06.040(c).
• Key standards: Specific numeric limits not found in the retrieved excerpts — Verify with the Code's Chapter 22.10 and development standards.

AG (Agricultural)

• Purpose: Applied on annexation where low density, agricultural, and compatible open space uses are desired. § 22.12.010.
• Typical uses: agricultural uses and single‑family residential at very low density. § 22.12.010 notes maximum new single‑family density of one dwelling per five gross acres.
• Key standards: Minimum lot area: 5 acres in Table 2‑9 for AG. Table 2‑9 / § 22.12.010.

OS (Open Space / Conservation)

• Purpose: Protect open space resources, scenic qualities, sensitive environmental features and hazards. § 22.12.010.
• Typical uses: conservation, passive recreation, limited public facilities consistent with open space. Specific allowed uses and numeric development limits are limited; the Code indicates special review and limits. § 22.12.010.

REC (Recreation)

• Purpose: Parks, golf courses, private recreation. § 22.06.020 and Table 2‑1.
• Typical uses: park and recreational facilities; development and standards depend on the specific recreational use and additional chapters (e.g., landscaping and parking). Table 2‑9 references park/rec standards.

SP (Specific Plan / Planning Area)

• Purpose: Areas controlled by an adopted specific plan; the specific plan governs standards and uses. § 22.06.020 and related chapters.
• Typical uses/standards: controlled by the adopted specific plan on file; check the specific plan text for exact uses and development standards.

Overlay districts — PD, C‑3‑PD/Hotel, (H) Housing Element site overlay, TCSP

• Purpose & how they work: Overlay symbols are appended to primary district symbols on the zoning map (e.g., RL‑PD); overlays add district‑specific rules on top of the primary district. § 22.14.020 (Applicability) and § 22.06.030(1) (map inclusion by reference).
• PD (Planned Development): Purpose is maximum flexibility for site‑specific planning; a Conditional Use Permit is required for development in PD. PD may modify lot area, setbacks, site coverage, FAR, height, landscaping, or parking by approval. § 22.14.030.
• C‑3‑PD / Hotel overlay: A site‑specific overlay that prioritizes hotel development and may limit non‑hotel uses until construction conditions are met; see § 22.14.040 for purpose and required findings.
• (H) Housing Element overlay: Applied to sites in the City’s 2021–2029 Housing Element to accommodate RHNA; multifamily dwellings are permitted and the standards of RH‑30 apply unless otherwise stated; special provisions exist for lower‑income sites (including minimum unit counts and ministerial review for certain affordable projects). § 22.14.050.
• TCSP (Town Center Specific Plan): Implemented via Chapter 22.11; all development is subject to the town center specific plan and special procedures for lower‑income sites per the housing element rules. § 22.11.020–.030.

Key decision‑relevant standards (quick table)

Checklist (minimum items an applicant must satisfy)

• Confirm parcel zoning on the official City of Diamond Bar Zoning Map (zoning map is adopted and on file). § 22.06.030.
• Confirm allowed uses and required permit type (P, MUP, CUP) using the use tables referenced in § 22.06.040(c).
• Meet site planning and development standards (setbacks, height, lot coverage, FAR) in the applicable chapter (residential Chapter 22.08, commercial Chapter 22.10, and General Standards Chapter 22.16). § 22.06.040(a); § 22.16.010.
• Provide required off‑street parking per the city Parking rules in Chapter 22.30. § 22.14.050(f) and § 22.06.040(c).
• Determine whether the site is in an overlay (for example PD, (H), C‑3‑PD) and comply with overlay special provisions (see Chapter 22.14). § 22.14.020.
• If proposing multifamily or projects subject to housing‑element provisions, follow special procedures in Chapter 22.18 and § 22.14.050 for the (H) overlay.
• If proposing an ADU, comply with the City ADU rules (ministerial/state law‑aligned) in § 22.42.120 and check ADUs.
• Prepare for design review and any required community review; check the City's Design Review rules and the Review Authority tables in Chapter 22.64.

Risks & Ambiguities

Plain‑English summary

Diamond Bar's zoning is organized by the City’s Title 22 Development Code: the official zoning map assigns one of a set of districts (residential bands like RL or RH‑30, commercial bands like C‑2/C‑3, industrial I, and overlays like PD and (H)) to every parcel; what you can build and what permit you need are set by the district rules, overlay text, the use tables, and the City’s development standards — check the parcel’s zoning map entry and the specific Code sections cited here before designing.

Source References

• § 22.06.020 — Zoning districts established (Table 2‑1: RR, RL, RLM, RM, RMH, RI‑1, RH‑30, OP, OB, CO, C‑1, C‑2, C‑3, I, AG, OS, REC, SP, PD, C‑3‑PD/Hotel).
• § 22.06.030 — Zoning map adopted; map interpretation rules.
• § 22.06.040(c) — How allowed uses and permit requirements are determined; reference to the use tables.
• § 22.10.020 — Purposes of commercial/industrial districts and FAR 0.25–1.00 for OP/OB/CO/C‑1/C‑2/C‑3.
• § 22.12.010 — AG (agricultural) district purpose and maximum density (1 unit / 5 acres).
• Table 2‑9 and related special purpose district standards (minimum lot area, height 35 ft for some special districts) — see Table 2‑9 and Chapter 22.14.
• § 22.14.030 — Planned Development (PD) overlay: flexibility, CUP requirement, and what PD may modify.
• § 22.14.040 — Adopted PD overlay districts and C‑3‑PD/hotel overlay narrative.
• § 22.14.050 — Housing element site (H) overlay: multifamily allowed, RH‑30 standards, density/parking/ministerial review provisions.
• § 22.42.120 — Accessory Dwelling Units (ADUs) — purpose and cross‑reference to state ADU law.
• § 22.16.010 — General Property Development and Use Standards (site planning purpose).
• Administrative/decision authority: Chapter 22.64 (City Council, Planning Commission, Director roles).

Retrieved passages

• Diamond Bar Zoning Code (section 22.06.020) High relevance show source text
• Diamond Bar Zoning Code (section 22.42.120) High relevance show source text
• CFC § 2 (Title 22) High relevance show source text
• Diamond Bar Zoning Code (section 22.44.020) High relevance show source text
• Diamond Bar Zoning Code (§ 2) High relevance show source text
• Diamond Bar Zoning Code (section 22.14.040) High relevance show source text
• Diamond Bar Zoning Code (title 7) High relevance show source text
• Diamond Bar Zoning Code (§ 2) High relevance show source text

Cited sections

• **§ 22.06.020** — Zoning districts established (Table 2‑1: **RR, RL, RLM, RM, RMH, RI‑1, RH‑30, OP, OB, CO, C‑1, C‑2, C‑3, I, AG, OS, REC, SP, PD, C‑3‑PD/Hotel**). (§ 22.06.020)
• **§ 22.06.030** — Zoning map adopted; map interpretation rules. (§ 22.06.030)
• **§ 22.06.040(c)** — How allowed uses and permit requirements are determined; reference to the use tables. (§ 22.06.040)
• **§ 22.10.020** — Purposes of commercial/industrial districts and FAR **0.25–1.00** for OP/OB/CO/C‑1/C‑2/C‑3. (§ 22.10.020)
• **§ 22.12.010** — AG (agricultural) district purpose and maximum density (1 unit / 5 acres). (§ 22.12.010)
• Table 2‑9 and related special purpose district standards (minimum lot area, height **35 ft** for some special districts) — see Table 2‑9 and Chapter 22.14. (Chapter 22.14.)
• **§ 22.14.030** — Planned Development (PD) overlay: flexibility, CUP requirement, and what PD may modify. (§ 22.14.030)
• **§ 22.14.040** — Adopted PD overlay districts and C‑3‑PD/hotel overlay narrative. (§ 22.14.040)
• **§ 22.14.050** — Housing element site **(H)** overlay: multifamily allowed, RH‑30 standards, density/parking/ministerial review provisions. (§ 22.14.050)
• **§ 22.42.120** — Accessory Dwelling Units (ADUs) — purpose and cross‑reference to state ADU law. (§ 22.42.120)
• **§ 22.16.010** — General Property Development and Use Standards (site planning purpose). (§ 22.16.010)
• Administrative/decision authority: **Chapter 22.64** (City Council, Planning Commission, Director roles). (Chapter 22.64)
• DiamondBar_ZoningCode.md

• Official Diamond Bar code library