California ADU rules · Los Angeles County
Can I Build an ADU in Sierra Madre?
Yes — you can build an ADU in Sierra Madre. California's statewide ADU law requires every city, including Sierra Madre, 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
CA state law1 ADU + 1 JADU
At least one ADU and one JADU per single-family lot (a conversion ADU may also be possible).
Units on a multifamily lot
Local ruleconversions (>=1 or 25% of units) + up to 2 detached
City limits detached ADUs on multifamily lots to 2, not 8 as in state baseline.
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
City sets a local maximum of 1,200 sq ft for detached ADUs.
Max attached ADU size
Local ruleUp to 50% of primary dwelling, not to exceed 1,200 sq ft
City sets a 1,200 sq ft cap on attached ADUs, even if 50% of primary would be larger.
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 ruleNo explicit front setback for ADUs; conversions may maintain existing setbacks
No explicit front setback for new ADUs; conversions can keep existing setbacks.
Separation from main house
Local ruleNone required
No specific separation required; must comply with fire/safety standards.
Parking
Parking required
Local ruleUp to 1 space
1 space per ADU unless exempted by listed conditions.
Transit parking exemption
Local ruleYes — no parking required near transit & for conversions
No parking required if within 1/2 mile of transit or other listed exemptions.
Garage-conversion replacement parking
Local ruleNot required
No replacement parking required when converting/demolishing a garage for an ADU.
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
Local ruleOnly for a JADU
Owner occupancy required only for JADUs, not ADUs.
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
Building permit required; safety inspection for conversions without permit record.
Sierra Madre-specific factors that can change the answer
State law sets the floor, but these local conditions often decide whether a specific parcel works.
Very High Fire Hazard Severity Zone (VHFHSZ)
ADUs must use fire-resistant materials and comply with hazardous brush clearance; sprinklers required only if primary residence requires them.
Historic District
Parking exemption applies; demolition of garages in historic districts may require notice.
Hillside (R-H zone)
ADUs allowed; parking exemption applies.
Sierra Madre limits detached ADUs on multifamily lots to 2, caps attached and detached ADUs at 1,200 sq ft, and provides detailed height and parking exemption rules. Fire hazard and historic district overlays impose additional requirements.
Frequently asked questions
Can I build an ADU in Sierra Madre?
Yes. California's statewide ADU law requires Sierra Madre 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 Sierra Madre?
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 Sierra Madre?
Side and rear setbacks are limited to 4 ft. No explicit front setback for ADUs; conversions may maintain existing setbacks.
Is parking required for an ADU in Sierra Madre?
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 Sierra Madre?
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 Sierra Madre?
Owner-occupancy: only for a jadu. ADUs under 750 sq ft are also exempt from impact fees.
Sources
- Sierra Madre Municipal Code Chapter 17.22 (ADUs & JADUs), Ord. No. 1454 (5-24-22), Ord. No. 1465 (3-28-23)
- SMMC 17.22.030(B)
- SMMC 17.22.040(A)
- SMMC 17.22.040(B)
- SMMC 17.22.040(D)
- SMMC 17.22.040(E)
- SMMC 17.22.050(A)
- SMMC 17.22.050(B)
- SMMC 17.22.050(C)
- SMMC 17.22.060(A)
- SMMC 17.22.070
- SMMC 8.36, 17.22.080
- SMMC 17.22.050(B)(2), 17.22.080
- SMMC 17.22.020, 17.22.050(B)(6)
- 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 § 66323 (by-right ADU/JADU, 800 sq ft, 4-ft setbacks)
- Cal. Gov. Code § 66333 (junior ADUs)
- Cal. Gov. Code § 66321 (size minimums & height)
- 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 Sierra Madre'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 Sierra Madre Planning before relying on it.
Will an ADU work on your Sierra Madre lot?
Ask GoCodebook about your address and get the size, setback, parking and permit rules that actually apply to your parcel — with the exact citation.
Check my parcel free