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421 Fair Oaks St

Noe Valley, SF 94110 6533043 4 units · 2 fl · 1961

This building has a higher-than-average number of open problems nearby. Few open issues; problems get fixed quickly. A reasonable bet for a smooth tenancy.

NOVs (7y) vs. neighborhood
Compared to a typical building in Noe Valley
At or below average
avg 1.2
0
FewerMore

This building has 0 novs (7y), at or below the Noe Valley average of 1.2.

Rent & eviction protection

Is 421 Fair Oaks 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 1961
2 or more units
4 units
Property type
Multi-Family Residential
Zoning
RH3
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.

Building characteristics
Units4
Floors2
Year built1961
Total area2,734 sq ft
Property typeMulti-Family Residential
Tax statusNone
Blocklot6533043
Ownership

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

Owner name
Duffy Frank & Monica Trust
Mailing address
Frank & Monica Duffy 2171 21St Ave San Francisco CA 94116
Last sale
062498

Landlord portfolio

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

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Augrented Insights
Initial analysis

The two-story, four-unit multi-family residential building at 421 Fair Oaks St in Noe Valley, owned by Duffy Frank & Monica Trust, has been standing since 1961 and has undergone several significant maintenance and safety improvements over the decades. The building's maintenance history includes a roofing project from 1989, though this permit has since expired, and completion of work to comply with a Department of Public Works report from 1983. In the mid-1980s, the property underwent important safety enhancements, including the installation of self-closing devices on entry and exterior doors, as well as modifications related to "Code work 3r-1179" in 1984.

The building has been subject to routine housing inspections over the years, with documented inspections in 2002, 2009, and most recently in 2017. While the 2009 inspection was resolved within one day, the status of 2017's inspection remains indeterminate in the records. The only recent complaint on file was a resolved 311 call from January 2021 regarding improperly affixed illegal postings, which was addressed by the Department of Public Works Operations. It's worth noting that there are no recorded building code violations or serious complaints in recent years, suggesting generally attentive property management during this period, though the age of some permits and the lack of more recent permits could indicate minimal recent modifications to the building's infrastructure or systems.

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

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Risk rating

How 421 Fair Oaks 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

Grade A–B — Low risk

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

Grade C — Moderate risk

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

Grade D–F — High risk

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

Neighborhood percentile
46th percentile

Out of 1879 buildings in this neighborhood, 1015 are predicted to be safer.

RiskiestSafest
Predicted 12-month outcome
74%
No DBI
violation
26%
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.

Neighborhood location

Precise location is a proxy for neighborhood-level risk — some SF blocks have systematically higher DBI activity.

Building permits, owner's portfolio

Permits pulled across all of this owner's buildings over 7 years.

12-Month severity forecast
No violation 59.9%
Moderate concern 17.4%
Severe concern 22.8%
Estimated probability of receiving a DBI Notice of Violation in the next 12 months at each severity level. Model: full_hgb_balanced.
Apartment reviews

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The story over time

421 Fair Oaks St event timeline

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

2025
Building Permit Jan 28
Re-roofing (no hot works). remove (e) roof covering and install self-adhesive modified bitumen with 2 layers of base (1-28lb, 1-80lb)
$8,000 · Complete

See all 1 events

Full history back to 2025 — violations, complaints, permits, buyouts, and fire incidents.

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Every record we have

Full data for 421 Fair Oaks St apartments

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

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

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