Home Additions in Milpitas, CA
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Who Decides Your Milpitas Addition
Under the zoning ordinance that took effect October 2, 2025:
- Small additions and alterations are decided by the Planning Director, unless exempt.
- Additions over 100% of the existing floor area, and upper-story additions over 50%, are decided by the Zoning Administrator.
- In the Hillside (“H”) district, all additions need a Site Development Permit decided by the City Council, and hillside additions must be designed by a licensed engineer or architect.
Single-story additions of 600 sq ft or less on the ground floor may qualify for Express Plan Review if no entitlements or structural system changes are involved.
Addition Work
Design Standards and Other Rules
- New second-story windows within 5 feet of a side line or 15 feet of a rear line need a 5-foot sill or obscured glass.
- Foundations for additions must match the existing system unless an engineer designs them.
- Milpitas Unified School District requires a Certificate of Compliance for additions of 500 sq ft or more before permit issuance.
- Removing a protected tree for a project needs a Public Works Tree Removal Permit, and sites with trees need a tree protection plan.
- HOA approval for exterior work where an HOA exists.
Fire sprinklers: required in new construction. An addition or alteration is treated as a “rebuild,” needing a residential sprinkler system, if it demolishes more than 50% of the exterior walls or roof structure, or reconfigures more than 75% of the interior including an attached garage.
Where to Start
Planning comes first: for additions and remodels, Milpitas requires Planning’s approval-to-proceed document to be uploaded with the building submittal. Building plan check does not start without it.
455 E. Calaveras Boulevard, Milpitas, CA 95035 · (408) 586-3000
Building Safety (408) 586-3240 · Planning (408) 586-3279 · Engineering (408) 586-3329 · Fire Prevention (408) 586-3365
Building counter weekdays 8 to noon and 1 to 5, with limited service Thursdays before 10 a.m.; last counter plan submittal at 4 p.m. Applications go through the City’s Building Online Permitting System.
Inspections can be booked online 24/7 or at (408) 586-2797. Windows are 7:30 a.m. to noon and noon to 3 p.m.; there are no inspections on Thursdays until after 9 a.m.
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See home additions and second stories.
Milpitas Home Additions FAQ
Who approves a large addition in Milpitas?
Additions over 100% of existing floor area and upper-story additions over 50% are decided by the Zoning Administrator.
What about hillside homes?
In the Hillside district, all additions need a City Council Site Development Permit.
Can a small addition be approved over the counter?
Single-story additions of 600 sq ft or less on the ground floor may qualify for Express Plan Review.
When are sprinklers required?
When the work demolishes more than half the exterior walls or roof structure, or reconfigures more than 75% of the interior.