Free SF apartment background check

640 Mason St

Union Square, SF 94108 0284025 52 units · 7 fl · 1932

This building has a higher-than-average number of open problems nearby. Renters here report frequent, slow-to-fix problems. Get repair promises in writing and check the unit before signing.

NOVs (7y) vs. neighborhood
Compared to a typical building in Union Square
At or below average
avg 6.9
0
FewerMore

This building has 0 novs (7y), at or below the Union Square average of 6.9.

Rent & eviction protection

Is 640 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 1932
2 or more units
52 units
Property type
Multi-Family Residential
Zoning
RC4
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
Units52
Floors7
Year built1932
Total area31,458 sq ft
Property typeMulti-Family Residential
Tax statusNone
Blocklot0284025
Ownership

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

Owner name
Orbelian Holdings Lp
Mailing address
608 48th Ave San Francisco CA 94121
Last sale
112912

Landlord portfolio

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

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Augrented Insights
Initial analysis

640 Mason Street is a 52-unit, seven-story multi-family residential building constructed in 1932, currently owned by Orbelian Holdings LP. The building has experienced several significant maintenance and safety issues in recent years, most notably a recurring problem with its elevator system, which has been reported as failing daily since March 2024, particularly affecting senior and disabled tenants. Multiple fire safety concerns have also emerged, with open violations as of December 2024 related to the high-rise sprinkler system, fire safety director compliance, and sleeping area requirements. The building has a documented pattern of fire safety violations, including problems with alarm systems, extinguishers, and general fire code compliance, with the most recent occurring in late 2024.

Recent building improvements include a July 2023 fire alarm system upgrade to comply with fire code requirements, and various unit renovations between 2010-2019 including kitchen remodels, electrical upgrades, and plumbing improvements. The property has faced several compliance challenges, including a 2016 Notice of Violation regarding a gate encroachment that required remediation by 2018, and multiple plumbing and electrical upgrades to various units over the years. A concerning complaint from 2019 documented a bed bug infestation originating from the building manager's unit, along with window ventilation issues and heating problems in unit 205. More recent complaints from 2024 indicate problems with hot water service, described as being throttled every Monday, and issues with the domestic hot water system. The building has undergone numerous routine health and safety inspections over the years, and while many violations have been abated, the persistent nature of recent fire safety concerns suggests ongoing compliance challenges.

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

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Risk rating

How 640 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
66th percentile

Out of 38 buildings in this neighborhood, 13 are predicted to be safer.

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

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 7.7%
Moderate concern 81.4%
Severe concern 10.9%
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

640 Mason St event timeline

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

2026
311 Request Apr 27
Garbage and debris
human waste or urine
DBI ComplaintJan 13
Date last observed: 12-jan-26; time last observed: every monday; exact location: main bldg; building type: residence/dwelling no hot water;

See all 16 events

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

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Every record we have

Full data for 640 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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