SB 1211 in San Mateo
San Mateo property owners with existing multifamily lots can now add up to 8 detached ADUs under SB 1211 — no hearings, no design review, no replacement parking. Here's what it means for property owners in San Mateo County.
The Bay Area angle
High land basis but tech-driven rents make ADU pro-formas pencil quickly — payback windows of 6–9 years are common. San Mateo's SB 1211 opportunity sits in the gap between what zoning historically allowed and what state law now requires cities to permit ministerially.
Worked example: an 8-unit building in San Mateo
An 8-unit existing multifamily property in San Mateo can add up to 10 new homes under SB 1211: 8 detached units (the statutory cap) plus 2 interior conversions. At San Mateo's median rent of $3,000/mo, that's roughly $360K in additional gross annual rent on land you already own.
Cities can't require less than SB 1211 allows; they can permit more. Several already do.
San Mateo jurisdiction notes
Peninsula tech rents; very strong upside. Like every California city, San Mateo cannot require less than SB 1211 allows — it can permit more.
Approval pathway in San Mateo
- Ministerial approval — no hearings, no comment period
- 4-foot side and rear setbacks
- 18-foot height limit
- No 1:1 replacement parking required (uncovered or covered)
- 75-130 days typical permit timeline
- Estimated eligible lot pool in San Mateo: 1,900
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Frequently asked questions about SB 1211 in San Mateo
Does SB 1211 apply to my San Mateo property?
If your lot in San Mateo (San Mateo County) currently has 2 or more legal residential units, yes — SB 1211 applies as state law and supersedes local ordinances that conflict with §66314. Single-family lots use SB 9 instead.
How long do permits take in San Mateo?
San Mateo typically issues SB 1211 permits in 75-130 days under ministerial review. Peninsula tech rents; very strong upside.
What's a San Mateo multifamily ADU actually worth?
At San Mateo's median 1BR rent of $3,000/month, an 8-detached-ADU project produces roughly $288K in additional gross annual rent — before counting interior conversions.
Can San Mateo require parking replacement?
No. §66313 prohibits cities — including San Mateo — from requiring 1:1 replacement of any parking spaces removed to build SB 1211 ADUs.
Are there San Mateo County overlays I need to worry about?
Possibly. Coastal-zone parcels, historic districts, and very-high fire-severity zones still trigger objective-standards review. But subjective design or neighborhood-character review is preempted.