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3173 21St St

Inner Mission, SF 94110 3615031B 4 units · 2 fl · 1900

A handful of records on file over the last seven years, and our model sees a moderate chance of more in the next 12 months. A few records worth reading before you sign. Check whether they were closed out, and ask what was actually fixed.

NOVs (7y) vs. neighborhood
Records already on file, against a typical building in Inner Mission — not a forecast
At or below average
avg 2.7
0
FewerMore

This building has 0 novs (7y), at or below the Inner Mission average of 2.7.

Rent & eviction protection

Is 3173 21St St rent-controlled?

San Francisco's Rent Ordinance caps rent increases and provides eviction protection for most residential units built before 1979 with 2+ units. Here's how this building scores.

Built before 1979
Built 1900
2 or more units
4 units
Property type
Multi-Family Residential
Zoning
NC3
Likely rent-controlled. Building age and unit count suggest this property falls under San Francisco's Rent Ordinance.

Based on SF Assessor records. Not legal advice — confirm with the SF Rent Board.

Statewide backstop · AB 1482

California Tenant Protection Act of 2019

Even when a building isn't covered by local rent stabilization, the statewide Tenant Protection Act (AB 1482) may still apply. It caps annual rent increases and requires the landlord to state a legal reason to end most tenancies.

15+ years since occupancy
Built 1900
Annual rent increase cap
5% + CPI, max 10%
Just-cause eviction
After 12 months
Local rent control likely takes priority. This building appears to fall under the local ordinance above, which is stronger than AB 1482. Where a local just-cause ordinance applies, its rules govern instead of the state cap.

AB 1482 does not apply to single-family homes and condos unless owned by a corporation, REIT, or an LLC with a corporate member; to owner-occupied duplexes; or to deed-restricted affordable housing. The Act is in effect until January 1, 2030. Not legal advice — see the California landlord–tenant guide.

Building characteristics
Units4
Floors2
Year built1900
Total area2,350 sq ft
Property typeMulti-Family Residential
Tax statusNone
Blocklot3615031B
Ownership

Registered owner per SF Assessor-Recorder (secured roll).

Owner name
Mailing address
P.o. Box 48 Millbrae CA 94030
Last sale
February 08, 1988

Landlord portfolio

Other SF properties this owner holds, with a risk rating for each.

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Multiple entrances & addresses

Included addresses

All street addresses sharing this blocklot that are covered by this report.

3173 A 21st St, San Francisco, CA 94110
3173 21st St, San Francisco, CA 94110
Augrented Insights
Initial analysis

The property at 3173 21st Street is a two-story, four-unit multi-family residential building with a ground-floor retail space, constructed in 1900 and currently owned by Dorothy I. Chao. The building has undergone several significant renovations and improvements over the past decade, with the most recent major work completing in late 2022, including the remodeling of tenant spaces and an all-gender restroom upgrade, along with associated plumbing and electrical work totaling $40,000. Previous improvements include a 2019 electrical upgrade to 400-amp service and maintenance of various units, including bathroom and kitchen remodels. The building has experienced some challenges, notably a fire incident in 2012 that affected the third floor, requiring repairs to the deck and exterior siding, and a mice infestation complaint from December 2022. Multiple violations related to building maintenance were recorded in 2007, including issues with windows, walls, and plumbing, though these were subsequently abated. Fire safety has been an ongoing concern, with several violations recorded between 2019-2023 related to extinguishers, blocked exits, and alarm systems, with a violation issued most recently in December 2023 regarding building contact information.

The property has seen consistent investment in maintenance and upgrades, with historical records showing attention to various building systems including electrical, plumbing, and fire safety. While there have been periods of maintenance issues, particularly in 2007-2008, the more recent history of the building shows regular improvements and compliance efforts. The ground floor retail space and the building's mixed-use nature have been central to its recent renovation activities, with permits showing conversion of garage areas to retail space and preparations for new tenants. Recent complaints regarding garbage and debris (January 2025) suggest ongoing external maintenance challenges, though these are more related to public space management than building condition itself.

AI-generated · may contain errors · check the source data tables below

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Risk rating

How 3173 21St St's risk score is calculated

We trained a model on 7 years of SF DBI inspection data — notice of violation filings, complaint history, and owner track records. It estimates the probability that DBI inspectors will issue a Notice of Violation at this address in the next 12 months. Lower % = safer.

What the score means for you

Lower risk — safer than most nearby

DBI rarely finds violations here. Strong maintenance history and a clean complaint record.

Typical — about average for the neighborhood

Some past violations or complaints on record. Worth asking the landlord about any open issues before signing.

Higher risk — riskier than most nearby

Elevated violation and complaint history. DBI has found issues here before and is statistically likely to again.

Neighborhood percentile
64thpercentile

Out of 2380 buildings in this neighborhood, 857 are predicted to be safer. The band is relative to this neighborhood, so a share of every neighborhood falls in each colour.

RiskiestSafest
Predicted 12-month outcome
72%
No DBI
violation
28%
DBI violation
likely
Model explanation

What's driving this score

The three data points that most influenced this building's risk rating — ranked by the weight the model placed on each one.

Number of units

The number of units affects how the model reads complaint and violation totals — more units means more potential sources.

DBI tenant complaints (past 7 years)

Formal complaints tenants filed with DBI about this building over 7 years.

Property class: apartment building

Apartment building — this property classification influences expected violation rates.

12-Month risk forecast
Moderate failure risk 28%
Estimated probability of receiving a DBI Notice of Violation in the next 12 months. Model: full_hgb_balanced.
Apartment reviews

3173 21St St apartment reviews

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On the map

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The story over time

3173 21St St event timeline

Violations, complaints, fire incidents, permits, and buyouts — most recent records in order.

2026
311 Request May 25
Garbage and debris
other loose garbage debris yard waste
311 RequestMay 16
Amplified sound electronics

See all 12 events

Full history back to 2020 — violations, complaints, permits, buyouts, and fire incidents.

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Every record we have

Full data for 3173 21St St apartments

13 SF public datasets for this parcel — permits, violations, complaints, fire records, 311 calls, planning records, and buyouts.

Side by side

How 3173 21St St compares to the neighborhood

This building against comparable properties in Inner Mission. Toggle filters to narrow the peer group.

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Cancel anytime · Data sourced from SF Open Data, DBI, SFFD, SF Rent Board & Planning

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