Local permit rules, fees, and timelines for San Marino, verified against city sources, plus the loan options NestMade matches to your equity and the rent your unit can earn.
San Gabriel Valley ADU Loans
An accessory dwelling unit adds rental income, room for family, and value to your San Marino property. The local details below — each checked against its city source — shape what you can build under California's ADU law and what it costs, alongside loan options matched to your equity and timeline.
The Numbers
San Marino home values support the equity an ADU loan draws on, and local rents shape whether the unit pays for itself.
The median value of owner-occupied homes in San Marino is at least $2,000,000+ — the Census Bureau caps its reported median at $2.0 million, so owners here hold exceptional equity to borrow against.
HUD's revised FY2026 Fair Market Rent for the Los Angeles County metro, which covers San Marino, is $2,079 for a studio, $2,328 for a one-bedroom, and $2,903for a two-bedroom. Fair Market Rent is HUD's 40th-percentile gross rent, so a newly built ADU often asks somewhat higher.
What You Can Build
What the city allows on a single-family lot, checked against the local ordinance and state law.
San Marino caps an ADU by bedroom count and lot size (Muni Code 23.02.25(H)(1)): studio/one-bedroom up to 850 sq ft, two-bedroom 1,000 sq ft, three-bedroom 1,200 sq ft, with ADUs limited to two bedrooms on lots under 12,000 sq ft and three on larger lots. A detached ADU may not exceed 1,200 sq ft and is one story / 16 ft (18 ft near transit, 20 ft to match roof pitch); an attached ADU is up to 50% of the primary dwelling (max 1,200 sq ft) and 25 ft. A JADU is 150–500 sq ft within the existing/proposed dwelling.
San Marino imposes detailed objective architectural standards on ADUs (Muni Code 23.02.25(H)): an ADU must exactly match the primary residence's building materials, colors, style, and form, with matching architectural details and no second-story balcony; it must comply with the City's Pre-Approved Roof Materials list and Window/Door Replacement procedures; exterior lighting must be shielded; windows must avoid direct line of sight to neighbors; and the exterior access door must not be visible from the street. A conforming ADU is approved ministerially without design review; a non-conforming one requires design review, a CUP, or a variance.
An ADU must conform to the underlying zone's lot coverage, floor area, and front-yard setback (Muni Code 23.02.25(H)(6)), except where doing so would block an 800 sq ft ADU at 16 ft with 4-ft side/rear setbacks, in which case the conflicting regulation is waived. Required side and rear setbacks are 4 ft for new construction (no setback for conversions within an existing structure). There is no ADU-specific front-yard landscaping percentage, though tree-retention and tree-permit requirements apply.
On a single-family residential lot, San Marino allows one converted ADU, one JADU, and the construction of one ADU, where these meet Government Code §66323 (Muni Code 23.02.25(E)(1)) — mirroring the state framework. For multifamily lots the ordinance allows up to one ADU within each unit up to 25% of existing units, plus up to eight detached ADUs.
Costs
What the city and school district charge, and where ADUs get a break.
Per San Marino's Schedule of Fees (effective July 13, 2025), the Accessory Dwelling Unit Permit is $45 per application but waived to $0 through June 30, 2026. Building plan check/inspection is not a flat fee — the City charges 85% of the LA County Building and Grading fees (LA County's expedited plan check adds 50%), so the cost is valuation-based. A Certificate of Occupancy is $180 and Fire Plan Review $160; a non-conforming ADU triggering discretionary review adds Administrative Design Review ($325) and a Major Plot Plan ($290). Credit-card payments add 3.0%.
Under state law (Gov. Code §66323), no impact fee may be imposed on an ADU under 750 sq ft, and a larger ADU's impact fees must be proportional to the primary dwelling; San Marino subjects ADU owners to applicable sewer, water, and other fees per Muni Code 23.02.25(G)(3) and requires no letters of water/sewer service availability. The school district is San Marino Unified, whose Level 1 residential developer fee is $4.79/sq ft, collected through the San Marino Community Development Division. Under state law, ADUs under 500 sq ft are exempt from school developer fees.
Process
How long it takes, and the shortcuts the city offers.
No. San Marino publishes no pre-approved or standard ADU plan sets (AB 1332). The City's adopted ADU ordinance acknowledges AB 1332 in its recitals but contains no pre-approved-plan program, and the city's applications list shows only an ADU Application plus pre-approved roof and window/door MATERIAL lists — not building plan sets. Treat San Marino as having no AB 1332 pre-approved ADU plans.
Per Muni Code 23.02.25, an ADU/JADU that meets the standards is approved by the City after a ministerial compliance review within 60 days of a complete application (a denial comes with a written list of deficiencies). Applications go to the Planning and Building Divisions concurrently with a building permit; JADUs, converted ADUs, and new detached ADUs meeting Gov. Code §66323 are exempt from a Planning ADU Application and proceed directly to a building permit. A non-conforming application is not approved ministerially and instead requires design review, a CUP, or a variance.
Watch-outs
A few local specifics that can affect where and whether you build.
Yes, on two fronts. Fire: San Marino has a designated Fire Hazard Severity Zone and runs a Wildland Fuel Management Program enforcing vegetation clearance in the Very High Fire Hazard Severity Zone, with annual June inspections; an ADU in this zone faces defensible-space and home-hardening expectations (confirm a parcel on the OSFM viewer). Historic: the ADU ordinance (Muni Code 23.02.25(H)(20)) imposes special standards on an ADU on a property listed on the National/California Register, a local landmark, or in a historic district — no change to the street-facing facade and exact matching of exterior details — and Mills Act contracts govern where applicable.
San Marino is served by a City-operated sanitary sewer system, not septic. The City's Parks & Public Works Department operates an approximately 50-mile gravity sewer collection system conveying wastewater to the LA County Sanitation District trunk system, with a new annual sewer service charge beginning July 1, 2025. No official source maps any San Marino area as septic or identifies a perc-test trigger for ADUs; an ADU connects to the City sewer.
No. No San Marino ordinance opting into AB 1033 (separate condominium conveyance of an ADU) exists. The ADU ordinance requires a recorded deed restriction that a JADU shall not be sold separately from the primary residence (Muni Code 23.02.25(F)(2)(a)) and contains no AB 1033 condo-sale program. Absent a local AB 1033 ordinance, separate condominium sale of an ADU is not available in San Marino.
Know Your Numbers
Pick your project and size for a quick, itemized estimate, then see whether to pay cash or finance it. Permit fees vary by city — the San Marino specifics are in the fees section above.
1 What do you want to build?
2 How big?
3 Your estimated cost in San Marino
Does it pencil?
The rent could fully cover the loan payment — about $1,140/mo left over.
Financing $154,000 at 8.5% over 30 years (illustrative). Potential rent is the HUD Fair Market Rent for LA County — your actual rate and rent will vary.
4 How will you pay for it?
Ballpark ranges based on 2025–26 Los Angeles–area ADU costs, not a quote. Your actual cost depends on your lot, finishes, site conditions, and city. Exact San Marino permit fees vary — see the fee details on this page. A NestMade advisor will give you real numbers for your project.
Information last verified June 2026 against official San Marino and California state sources.
The permit rules, fees, timelines, and figures on this page are provided for general informational purposes only and are not legal, tax, financial, or lending advice. Local ordinances and fee schedules change frequently, and your property's specifics may differ. Confirm current requirements directly with the City of San Marino and do your own research with the appropriate licensed professionals before making decisions about your ADU. Cost figures are estimates; loan options are subject to credit approval and are not a commitment to lend.
San Gabriel Valley
ADU rules and fees differ from one city to the next. Explore the guidance for a nearby city, or see them all.
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