Diamond Bar · Zoning · RLM
Diamond Bar RLM zoning: height, setbacks and lot size
In Diamond Bar's RLM zone, generally buildings can be up to 35 ft tall, the front setback is 20 ft and the minimum lot size is 8,000 sq. ft., with the conditions listed below (Diamond Bar code, read October 2026).
Key points
- Maximum building height: 35 ft
- Minimum front setback: 20 ft
- Minimum side setback: 5 ft (One side only; the other side needs 10 ft. Structures on adjoining parcels must be at least 15 ft apart)
- Minimum rear setback: 20 ft (From the property line or buildable pad on a descending slope, whichever is applicable.)
- Minimum lot size: 8,000 sq. ft. (Minimum area for parcels proposed in new subdivisions; exceptions and alternative ownership parcel sizes are described in footnote (1).)
- Maximum lot coverage: 40%
- Maximum density: 1 single-family unit per lot
RLM is a zoning district in Diamond Bar. Every value below was read from the Diamond Bar Municipal Code and links to its section (read October 2026). State laws such as the ADU and SB 9 rules can allow more on a residential lot. General information, not legal advice — read the code text and check with the city before you build.
Development standards in RLM
The general rule for a typical lot in this zone. Zoning tables often attach notes, such as rules for corner lots, lots next to a residential zone, or new subdivisions only. Open “code text” under a value to see the table cell or sentence it was read from.
| Maximum building height | 35 ft See note 5 below the table in the code. § 22.08.040 · code textTable row “Height limit (5)”, column “RLM”: 35 ft. Note 5: Maximum allowable height for structures. See section 22.16.060 (Height measurement and height limit exceptions). |
|---|---|
| Minimum front setback | 20 ft See note 3 below the table in the code. § 22.08.040 · code textTable row “Front (3)”, column “RLM”: 20 ft. Note 3: Front setbacks listed are minimums. For single-family detached tract development, a minimum five-foot setback variation for adjacent residential units is required. |
| Minimum side setback | 5 ft Applies: One side only; the other side needs 10 ft. Structures on adjoining parcels must be at least 15 ft apart See note 4 below the table in the code. § 22.08.040 · code textTable row “Sides (each) (4)”, column “RLM”: 10 ft. on one side, and 5 ft. on the other; but not less than 15 ft. between structures on adjoining parcels Note 4: See section 22.68.030(b)(2) for nonconforming side setbacks and distance separations to dwelling units. |
| Minimum rear setback | 20 ft Applies: From the property line or buildable pad on a descending slope, whichever is applicable. § 22.08.040 · code textTable row “Rear”, column “RLM”: 20 feet from the property line or buildable pad on a descending slope whichever is applicable |
| Minimum lot size | 8,000 sq. ft. Applies: Minimum area for parcels proposed in new subdivisions; exceptions and alternative ownership parcel sizes are described in footnote (1). See note 1 below the table in the code. § 22.08.040 · code textTable row “Minimum lot area (1)”, column “RLM”: 8,000 sq. ft. Note 1: Minimum area for parcels proposed in new subdivisions, except as otherwise provided by section 22.08.050 (Minimum lot area), and chapter 22.22 (Hillside Management). Condominium, townhome, or planned development projects may be subdivided with smaller parcel sizes for ownership purposes, with the minimum lot area requirement determined through the subdivision review process, provided that the over |
| Maximum lot coverage | 40% § 22.08.040 · code textTable row “Lot Coverage”, column “RLM”: 40 percent |
| Maximum density | 1 single-family unit per lot See note 2 below the table in the code. § 22.08.040 · code textTable row “Residential density (2)”, column “RLM”: 1 single-family unit per lot; 5 per gross acre Note 2: Maximum number of dwellings allowed for each specified unit of land. The approval of a conditional use permit within areas subject to section 22.22.040 (Hillside management—Density) may result in fewer dwelling units being allowed than the maximum density shown. See also chapter 22.18 (Affordable Housing Incentives/Density Bonus Provisions) for possible density bonuses. |
Uses in RLM
Uses the code's use tables allow in RLM, or allow with a permit. Each links to its page with the code section.
- Single-family home — Allowed
- Bed and breakfast — Needs a conditional use permit
- Private school — Needs a conditional use permit
When a different number applies
The code sets other values for particular lots, buildings or locations in RLM:
- Minimum side setback: 10 ft — On one side; the other side needs 5 ft § 22.08.040
- Maximum density: 5 units per gross acre — Overall cap, measured per gross acre of land § 22.08.040
Not on this page
We did not find a general stories, FAR limit for RLM in the zoning tables we read. The code may still set one elsewhere — check the Diamond Bar Municipal Code.
Other Diamond Bar zoning districts
Who this affects
Frequently asked questions
What is the maximum building height in Diamond Bar's RLM zone?
35 ft — Diamond Bar Municipal Code § 22.08.040.
What is the minimum front setback in Diamond Bar's RLM zone?
20 ft — Diamond Bar Municipal Code § 22.08.040.
What is the minimum side setback in Diamond Bar's RLM zone?
5 ft (one side only; the other side needs 10 ft. Structures on adjoining parcels must be at least 15 ft apart) — Diamond Bar Municipal Code § 22.08.040.
What is the minimum rear setback in Diamond Bar's RLM zone?
20 ft (from the property line or buildable pad on a descending slope, whichever is applicable) — Diamond Bar Municipal Code § 22.08.040.
What is the minimum lot size in Diamond Bar's RLM zone?
8,000 sq. ft. (minimum area for parcels proposed in new subdivisions; exceptions and alternative ownership parcel sizes are described in footnote (1)) — Diamond Bar Municipal Code § 22.08.040.
General information, not legal advice.
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