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1839-1843 Mason St

Russian Hill, SF 94133 0100004 3 units · 3 fl · 1908

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 Russian Hill
At or below average
avg 1.9
0
FewerMore

This building has 0 novs (7y), at or below the Russian Hill average of 1.9.

Rent & eviction protection

Is 1839-1843 Mason 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 1908
2 or more units
3 units
Property type
Multi-Family Residential
Zoning
RM1
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
Units3
Floors3
Year built1908
Total area4,434 sq ft
Property typeMulti-Family Residential
Tax statusHome Owners
Blocklot0100004
Ownership

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

Owner name
Wu Simon
Mailing address
1843 Mason St San Francisco CA 94133
Last sale
091613

Landlord portfolio

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

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Multiple entrances & addresses

Included addresses

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

1843 Mason St, San Francisco, CA 94133
1839 Mason St, San Francisco, CA 94133
1841 Mason St, San Francisco, CA 94133
Augrented Insights
AI summary

The property at 1839-1843 Mason Street is a three-story, three-unit multi-family residential building constructed in 1908, currently owned by Simon Wu. The building has undergone several significant maintenance and repair activities over the past two decades. Most notably, in October 2013, the building received a $5,000 reroofing project, and an earlier $2,000 repair to the back stairs was completed in 2006. The building has experienced multiple safety inspections, with two significant routine inspections occurring in 2006 and 2015. The 2015 inspection revealed several safety compliance issues, including the need for carbon monoxide alarms and various fire safety requirements, though these violations were abated by June 2015. There was a concerning pattern of violations in the early 2000s, including issues with stairs, fire extinguishers, smoke detectors, and a possibly unauthorized roof deck.

Of particular note is an active complaint from January 2003 regarding unauthorized conversions of the three-unit building into individual rooms with multiple families, which appears to have remained unresolved in the records. The building has also faced historical challenges regarding unauthorized units in the basement, with multiple complaints filed in 1995. Recent history shows relatively few building-specific issues, though there have been various street-level concerns recorded through 311 calls, mainly related to parking violations and general cleaning of the surrounding area. The property has experienced two emergency medical service incidents, though neither resulted in civilian injuries, and there have been no recorded fire incidents impacting the building directly.

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Risk rating

How 1839-1843 Mason 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
50th percentile

Out of 1133 buildings in this neighborhood, 566 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.

DBI complaint rate, owner's portfolio

Per-building complaint rate across the owner's portfolio.

Building age

Older buildings tend to have more maintenance challenges; SF's pre-1906 earthquake housing stock carries distinct risk.

Permit rate, owner's portfolio

Per-building permit rate across the owner's portfolio.

12-Month severity forecast
No violation 50.8%
Moderate concern 18.6%
Severe concern 30.6%
Estimated probability of receiving a DBI Notice of Violation in the next 12 months at each severity level. Model: full_hgb_balanced.
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The story over time

1839-1843 Mason St event timeline

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

2025
311 Request Jul 08
Garbage and debris
furniture

See all 2 events

Full history back to 2023 — violations, complaints, permits, buyouts, and fire incidents.

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Every record we have

Full data for 1839-1843 Mason 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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