Free SF apartment background check

42 Sumner St

South of Market, SF 94103 3730044 2 units · 2 fl · 1906

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 South of Market
At or below average
avg 3.3
0
FewerMore

This building has 0 novs (7y), at or below the South of Market average of 3.3.

Rent & eviction protection

Is 42 Sumner 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
2 units
Property type
Multi-Family Residential
Zoning
RED
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
Units2
Floors2
Year built1906
Total area2,300 sq ft
Property typeMulti-Family Residential
Tax statusNone
Blocklot3730044
Ownership

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

Owner name
Wang Xiaoning & Guo Yu
Mailing address
1047a Oak St San Francisco CA 94103
Last sale
082119

Landlord portfolio

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

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Augrented Insights
Initial analysis

The two-unit, 2-story multi-family residential building at 42 Sumner Street, owned by Wang Xiaoning & Guo Yu, was constructed in 1906 and has undergone several significant renovations and repairs over the past three decades. The most recent major improvements occurred in 2018, including the addition of a new bathroom, kitchen remodeling, and comprehensive electrical and plumbing upgrades, with a total investment of approximately $65,000. The building has a history of moisture-related issues, with notable problems documented between 2003-2005 including reports of mold and ceiling leaks, particularly affecting bathrooms and stairs. These earlier issues prompted several completed repairs in 2005, such as stair replacements, weatherproofing work, and window repairs.

The property has maintained regular maintenance standards since the mid-2000s, with no active building violations on record. Three plumbing and electrical permits from 2018 indicate substantial infrastructure upgrades, including complete rewiring of one unit and installation of modern fixtures. Historical complaints from 2003-2004 cited various interior problems which were subsequently addressed, including damage to walls, ceilings, and tiles, though some of these issues reemerged in a 2015 complaint regarding bathroom and basement conditions. Recent 311 calls between 2023-2024 primarily relate to street-level urban management issues such as encampments and sidewalk cleaning, rather than building-specific concerns, and there have been three documented fire department responses to the building, all for non-injury-related incidents. The property's maintenance history suggests that while it experienced significant structural and maintenance challenges in the early 2000s, subsequent renovations and repairs have substantially improved the building's condition, particularly through the major upgrades completed in 2018.

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

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Risk rating

How 42 Sumner 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
81th percentile

Out of 430 buildings in this neighborhood, 82 are predicted to be safer.

RiskiestSafest
Predicted 12-month outcome
83%
No DBI
violation
17%
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.

Neighborhood (ZIP code)

The ZIP code captures local housing market and enforcement patterns that affect all buildings in the area.

DBI complaints, owner's portfolio

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

Neighborhood location

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

12-Month severity forecast
No violation 80.1%
Moderate concern 10.8%
Severe concern 9.1%
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

42 Sumner St event timeline

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

2026
311 Request Jan 03
Garbage and debris
human waste or urine

See all 1 events

Full history back to 2026 — violations, complaints, permits, buyouts, and fire incidents.

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Every record we have

Full data for 42 Sumner St apartments

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

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