Pre-approved plans
Checked 2026-09-10For new detached units: reduced plan-review fee and turnaround cut by as much as half. Under state law a detached unit built from a pre-approved plan gets a 30-day decision instead of 60.
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Building an ADU in Milpitas
The only city currently paying homeowners' permit fees, with money the city expects to run out by the end of 2026. It also layers more design rules than its neighbours: matching materials and roof pitch, side or rear entrances, down-lighting, screening, and a 50% lot-coverage cap.
Most cities in Santa Clara County make building an ADU possible. Milpitas has spent several years actively paying people to do it, and it runs a second programme aimed squarely at owners of units that were built without permits. If you own property in Milpitas, these are worth understanding before you plan anything else, because they change the arithmetic more than any design decision will.
Programs and incentives
- Limited funding
ADU Incentive Program
Covers city permit costs on eligible ADU and JADU projects on single-family and duplex lots, averaging about $5,000 per unit. Reinstated with Community Investment Fund money; the city projects funds exhausted by end of 2026. School fees over 750 sq ft and utility connections are excluded.
Milpitas's page → Checked 2026-09-10 - Active
Safe ADU Legalization
A path to legalise units or conversions built without permits: anonymous self-assessment, a consultation with no name or address required until scheduling, then a courtesy inspection. Dovetails with AB 2533.
Milpitas's page → Checked 2026-09-10 - Active
Paid expedited plan review
Roughly halves the target turnaround, subject to staff availability.
Milpitas's page → Checked 2026-09-10
In more detail
The ADU Incentive Program covers your permit costs
Time-limitedMilpitas subsidises the permit fees on a new ADU — the city puts the average at around $5,000 a unit. The programme was originally funded with federal ARPA money, ran from March 2022, and closed in February 2024 when that funding was exhausted. It has since been reactivated, and the city projects the current funding will be fully disbursed by the end of 2026. That makes it genuinely time-limited rather than a standing benefit: the money runs out when it runs out.
Safe ADU Legalization, for units built without permits
If a garage was converted or a unit built without permits — often by a previous owner — Milpitas runs a dedicated path to legalise it rather than penalise it. It covers conversions of garages, rooms and existing structures as well as units built new without a permit, and it dovetails with the state's AB 2533 amnesty for unpermitted ADUs constructed before January 2020. The city publishes its own AB 2533 fact sheet alongside it.
A pre-approved plan program on top of both
Milpitas also publishes pre-approved ADU plans. Building a detached unit from one drops the city's decision clock from 60 days to 30 under state law — and that clock accepts a plan pre-approved by any agency in California, not only Milpitas's own.
Local rules worth knowing
- Maximum size. 850 sq ft (studio or one bedroom) or 1,000 sq ft (two bedrooms); 1,200 sq ft in the Hillside District; attached units capped at 50% of the main home. Source →
- Height. Detached 16 ft; 18 ft near transit; up to 20 ft if the roof pitch matches the main home. Attached up to 25 ft.
- Setbacks. Front 25 ft; side and rear 4 ft; at least 5 ft from the main home.
- Lot coverage. The unit may not push total coverage above 50%.
- Design. Materials and colours must match the main home; roof slope must match; entrance on the side or rear; down-lights only; frosted second-storey windows toward neighbours; evergreen screening or a 6 ft fence.
- Parking. One off-street space unless a state exemption applies.
- Short-term rental. 30-day minimum for ADUs and JADUs.
What's true in Milpitas because it's true everywhere
State law sets a floor no ordinance can go under. The full guide, with every statute cited →
An ADU is allowed on your lot
Every lot zoned for residential use may have at least one ADU, and a single-family lot may also add a JADU. A city cannot say no to the category.
800 sq ft by right
A detached or attached unit of up to 800 sq ft, 16 ft tall, with 4 ft side and rear setbacks must be approved regardless of local lot-coverage or floor-area limits.
Four-foot setbacks
A city cannot require more than four feet from side and rear lot lines for an ADU.
A 60-day decision
Once your application is complete the city has 60 days to approve or deny; 30 if you build from a pre-approved plan.
No replacement parking
Convert or demolish a garage to build an ADU and the spaces you lose never have to be replaced.
No impact fees under 750 sq ft
Prohibited entirely below 750 square feet, and proportional above it.
Ministerial review
Reviewed against an objective checklist. No design review board, no hearing, no discretion about whether they like it.
No owner-occupancy rule for an ADU
A city cannot require you to live on the property for a standard ADU. A JADU is different: since 1 January 2026 owner occupancy is required when the JADU shares sanitation with the main house.
We build here
Milpitas is inside our service area, and ADUs are all we do. We bring in the architect and engineer or work with yours, run the permit with Milpitas, and build with our own crew: about 6 weeks of construction for a detached unit once the permit is in hand.
What we can't tell you from here is what your particular lot will take: setbacks, the sewer lateral, the panel, grade and access. That is what the free site walk is for.