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1423-1427 Mason St

Nob Hill, SF 94133 0158007 4 units · 3 fl · 1913

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 Nob Hill
At or below average
avg 2.4
0
FewerMore

This building has 0 novs (7y), at or below the Nob Hill average of 2.4.

Rent & eviction protection

Is 1423-1427 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 1913
2 or more units
4 units
Property type
Multi-Family Residential
Zoning
RM2
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
Floors3
Year built1913
Total area4,923 sq ft
Property typeMulti-Family Residential
Tax statusHome Owners
Blocklot0158007
Ownership

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

Owner name
Leong James
Mailing address
1585 Marlborough Rd Hillsborough CA 94010
Last sale
081518

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.

1427 Mason St, San Francisco, CA 94133
1423 Mason St, San Francisco, CA 94133
1425 Mason St, San Francisco, CA 94133
Augrented Insights
Initial analysis

The property at 1423-1427 Mason Street is a 3-story multi-family residential building with 4 units, located in San Francisco's Nob Hill neighborhood. Built in 1913 and owned by James Leong, this flats and duplex-style building has undergone several significant improvements over the past decades. Most notably, in 2019, a comprehensive top-floor renovation was completed at a cost of $45,819, which included kitchen remodeling, bathroom renovations, electrical upgrades (including a new 100-amp subpanel and GFI installations), and the addition of modern appliances and smoke detectors. The building had a routine safety inspection in 2015 that identified several fire safety issues, including the need for carbon monoxide alarms and fire extinguishers, along with the removal of a wooden utility ladder for roof access; these violations were all abated by June 30, 2015.

Earlier improvements included stairway repairs and fence replacement in 2005, and there are records of several street space permits over the years, with the most recent street space permit issued in 2019. The building's maintenance history shows attention to both structural and safety concerns, though a side sewer vent cover was reported missing in May 2020 and remains an open issue as of this report's creation. The property has generated several parking-related complaints in recent years, with the most recent occurring in January 2024, though these are external issues not directly related to the building's condition or management.

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

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Risk rating

How 1423-1427 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
92th percentile

Out of 1125 buildings in this neighborhood, 90 are predicted to be safer.

RiskiestSafest
Predicted 12-month outcome
87%
No DBI
violation
13%
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.

Owner's portfolio size

Number of SF parcels this owner is registered on — larger portfolios have distinct risk patterns.

Construction spend, owner's portfolio

Estimated permit value across all of this owner's buildings.

12-Month severity forecast
No violation 58.4%
Moderate concern 19.8%
Severe concern 21.8%
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

1423-1427 Mason St event timeline

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

2019
Building Permit Oct 31
Street space
Issued
Building PermitAug 01
Top floor: remodel 8' x 15' kitchen, replace cabinet, install gfi, install appliances. remodel 2 bathroom (5'x7')&(3'x5') replace toilet, bathtub and sink. install gfi into bathroom. install panel. replace lights and install outlets in whole aprartment.

See all 4 events

Full history back to 2019 — violations, complaints, permits, buyouts, and fire incidents.

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Every record we have

Full data for 1423-1427 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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