California ADU rules · Contra Costa County
Can I Build an ADU in Pleasant Hill?
Yes — you can build an ADU in Pleasant Hill. California's statewide ADU law requires every city, including Pleasant Hill, to approve a qualifying accessory dwelling unit by right, plus a junior ADU (JADU) on a single-family lot. What varies city to city are the local specifics below.
Can you build one?
ADUs allowed
CA state lawYes — by right
ADUs and JADUs are allowed by right in all residential and mixed-use zones; ministerial approval, no hearing.
Units on a single-family lot
Local rule1 detached ADU + 1 JADU OR 1 converted ADU + 1 JADU (detached and converted ADUs may be combined with a JADU, subject to requirements)
Pleasant Hill allows either 1 detached or 1 converted ADU plus 1 JADU on a single-family lot, with some flexibility in combining types.
Units on a multifamily lot
Local ruleConverted ADUs: at least 1, up to 25% of existing units from non-livable space; Detached ADUs: up to 2 on a lot with a proposed multifamily dwelling, or up to 8 on a lot with an existing multifamily dwelling, not to exceed the number of existing units
Detached ADUs on multifamily lots are capped at the number of existing units, with a maximum of 8.
Junior ADU (JADU)
CA state lawAllowed
Up to 500 sq ft, within the walls of an existing single-family home (single-family lots only).
Size & height
Max detached ADU size
Local rule1,200 sq ft
Detached ADUs may be up to 1,200 sq ft, subject to lot coverage/FAR and other standards.
Max attached ADU size
Local ruleUp to 1,200 sq ft, but limited to 50% of the floor area of the existing primary dwelling; must allow at least 800 sq ft regardless of percentage
Attached ADUs are capped at 1,200 sq ft or 50% of the primary, whichever is less, but at least 800 sq ft must be allowed.
Guaranteed minimum size
CA state law800 sq ft
An 800 sq ft ADU must be allowed regardless of FAR/lot-coverage caps; a city also cannot cap an attached ADU below 850 sq ft (1,000 for 2+ bedrooms).
Max JADU size
CA state law500 sq ft
Max height
CA state law16 ft
16 ft baseline; cities must allow 18 ft within ½ mi of a major transit stop or where the primary dwelling is two-story, and 20 ft on a lot with a multistory multifamily building.
Setbacks
Side setback
CA state law4 ft
A city cannot require more than 4 ft side or rear setback; conversions of existing structures are exempt.
Rear setback
CA state law4 ft
Front setback
Local ruleVaries by zoning district: 20 ft in most single-family zones, 25 ft in R-20, 15 ft in RMD, 10–15 ft in multifamily/mixed-use
Front setback is not uniform; depends on base zoning.
Separation from main house
CA state lawNone required
No statewide separation requirement between the ADU and the primary dwelling.
Parking
Parking required
CA state lawUp to 1 space
At most 1 space per ADU (or per bedroom, whichever is less) — and waived in the common cases below.
Transit parking exemption
CA state lawYes — no parking required near transit & for conversions
No parking may be required within ½ mi walking distance of transit, in a historic district, for an ADU within an existing structure, within one block of car-share, or in certain permit-parking areas.
Garage-conversion replacement parking
CA state lawNot required
When a garage/carport is demolished or converted to build an ADU, replacement parking cannot be required.
Approval, timeline & cost
Approval path
CA state lawMinisterial (by right)
No public hearing or discretionary design review for a qualifying ADU.
Approval timeline
CA state law60 days
The agency must act within 60 days of a complete application — and the ADU is deemed approved if it does not.
Owner-occupancy
CA state lawOnly for a JADU
No owner-occupancy requirement for ADUs (the prior sunset was removed). A JADU may require owner-occupancy, principally where it shares sanitation with the main house.
Impact-fee waiver
CA state lawWaived under 750 sq ft
An ADU of 750 sq ft or less pays no impact fees (the 750 sq ft threshold itself is exempt under § 66311.5); larger ADUs pay fees proportional to the primary dwelling. JADUs (≤ 500 sq ft) are exempt.
Permits required
Local ruleBuilding permit, ADU permit
Both an ADU permit and a building permit are required.
Pleasant Hill-specific factors that can change the answer
State law sets the floor, but these local conditions often decide whether a specific parcel works.
Fire sprinklers
Sprinklers required in ADU only if required in primary dwelling
Historic district
No ADU-specific overlay, but historic districts may affect demolition/alteration
Pleasant Hill allows up to 1,200 sq ft detached or attached ADUs, with front setbacks varying by zone and a nuanced multifamily ADU cap. Both an ADU permit and building permit are required.
Frequently asked questions
Can I build an ADU in Pleasant Hill?
Yes. California's statewide ADU law requires Pleasant Hill to approve a qualifying accessory dwelling unit ministerial (by right), plus a junior ADU (JADU) on a single-family lot.
How big can an ADU be in Pleasant Hill?
A detached ADU of at least 1,200 sq ft must be allowed, and an ADU of 800 sq ft can never be zoned out by floor-area or lot-coverage limits. A JADU can be up to 500 sq ft.
What are the setback requirements for an ADU in Pleasant Hill?
Side and rear setbacks are limited to 4 ft. Varies by zoning district: 20 ft in most single-family zones, 25 ft in R-20, 15 ft in RMD, 10–15 ft in multifamily/mixed-use.
Is parking required for an ADU in Pleasant Hill?
Up to 1 space. No parking can be required within ½ mile of transit, for conversions, or for units inside the primary home. When a garage is converted, replacement parking is not required.
How long does ADU approval take in Pleasant Hill?
A complete application must be acted on within 60 days, with ministerial (by right) — no public hearing or discretionary design review for a qualifying ADU.
Do I have to live on the property to build an ADU in Pleasant Hill?
Owner-occupancy: only for a jadu. ADUs under 750 sq ft are also exempt from impact fees.
Sources
- Pleasant Hill Municipal Code § 18.15.050 (Ord. 978, 11/17/2025; Ord. 980, 12/15/2025)
- PHMC § 18.15.050.F.1.a–d
- PHMC § 18.15.050.H.1.a
- PHMC § 18.15.050.H.1.b
- PHMC § 18.15.050.H.2
- PHMC § 18.15.050.F, K
- PHMC § 18.15.050.G.3
- Cal. Gov. Code §§ 66310–66342 (ADU Law)
- HCD 2025 Accessory Dwelling Unit Handbook
- Cal. Gov. Code § 66317 (ministerial approval, 60-day deadline)
- Cal. Gov. Code § 66333 (junior ADUs)
- Cal. Gov. Code § 66321 (size minimums & height)
- Cal. Gov. Code § 66323 (by-right ADU/JADU, 800 sq ft, 4-ft setbacks)
- Cal. Gov. Code § 66322 (ADU parking; § 66334 covers JADU parking)
- Cal. Gov. Code § 66314 (local ordinance standards)
- Cal. Gov. Code § 66315 (owner-occupancy)
- Cal. Gov. Code § 66311.5 (impact fees: none for an ADU ≤ 750 sq ft or JADU ≤ 500 sq ft)
Last updated 2026-06-25. This is an AI-assisted summary of Pleasant Hill's ADU rules, drawn from its published ordinance and California ADU law — general information, not legal advice, and it may be incomplete or out of date. Verify the controlling rule for your specific parcel with Pleasant Hill Planning before relying on it.
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