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423-431 Union St

Telegraph Hill, SF 94133 0115054 6 units · 3 fl · 1906

A handful of records on file over the last seven years, and our model predicts a high risk of further maintenance problems 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 Telegraph Hill — not a forecast
At or below average
avg 1.2
1
FewerMore

This building has 1 novs (7y), at or below the Telegraph Hill average of 1.2.

The bar and the rating point different ways because they measure different things: the bar counts DBI violations already on file, the rating forecasts the next 12 months.

Rent & eviction protection

Is 423-431 Union 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 1906
2 or more units
6 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.

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 1906
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
Units6
Floors3
Year built1906
Total area6,355 sq ft
Property typeMulti-Family Residential
Tax statusNone
Blocklot0115054
Ownership

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

Mailing address
Gilbert William F & Lee Ann Po Box 620099 Woodside CA 94062
Last sale
March 30, 2017

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.

423 Union St, San Francisco, CA 94133
429 Union St, San Francisco, CA 94133
431 Union St, San Francisco, CA 94133
425 Union St, San Francisco, CA 94133
427 Union St, San Francisco, CA 94133
Augrented Insights
Initial analysis

The building at 423-431 Union Street in Telegraph Hill is a three-story multi-family residential structure built in 1906, currently owned by the Gilbert Family 1991 Trust. The property, originally consisting of 6 units, has undergone significant modernization and safety improvements over recent years, including comprehensive fire safety upgrades. Most notably, in 2024, the building received a new fire alarm system and underwent a major fire sprinkler installation project covering the basement and new ADUs on the first floor. The building is in compliance with the San Francisco Mandatory Soft Story Retrofit Program, having completed required seismic upgrades in 2024, which included soft-story retrofit work at the basement level and ADA improvements to the first-floor retail space. Recent improvements also include HVAC upgrades, with the installation of new high-efficiency furnaces and heat pumps throughout the building.

The property has experienced some maintenance and safety issues in the past, including lead paint concerns documented in complaints from 2013-2014, which were subsequently addressed. A 2022 complaint regarding garbage area access was resolved, and there have been several 311 calls regarding debris and cleaning issues near the property, most recently in 2024. The building underwent substantial renovation work in 2020-2023, including the removal of non-permitted units and conversion of commercial space into additional residential units, bringing the total to 8 residential units. This extensive work also incorporated new plumbing and electrical systems, with permits showing ongoing maintenance and system upgrades throughout 2023-2024. The most recent inspections and permits indicate that the property is actively maintaining compliance with current building codes and safety requirements, with all major outstanding issues having been addressed or resolved.

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

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Risk rating

How 423-431 Union 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
10thpercentile

Out of 684 buildings in this neighborhood, 616 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
37%
No DBI
violation
63%
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.

Building size

Total floor area — a proxy for building scale and the number of systems (plumbing, electrical, HVAC) that can fail.

Director's hearings (past 7 years)

Director's hearings are escalated enforcement actions for buildings that haven't resolved violations — a serious signal.

12-Month risk forecast
High failure risk 63%
Estimated probability of receiving a DBI Notice of Violation in the next 12 months. Model: full_hgb_balanced.
Apartment reviews

423-431 Union St apartment reviews

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On the map

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The story over time

423-431 Union St event timeline

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

2026
311 Request Jul 29
Garbage and debris
other loose garbage debris yard waste
311 RequestJul 23
Public works

See all 20 events

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

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Every record we have

Full data for 423-431 Union St apartments

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

Side by side

How 423-431 Union St compares to the neighborhood

This building against comparable properties in Telegraph Hill. 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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