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21-23 Prospect Ave

Bernal Heights, SF 94110 5611047 2 units · 2 fl · 1979

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 Bernal Heights
At or below average
avg 1.2
0
FewerMore

This building has 0 novs (7y), at or below the Bernal Heights average of 1.2.

Rent & eviction protection

Is 21-23 Prospect Ave 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 1979
2 or more units
2 units
Property type
Multi-Family Residential
Zoning
RH2
Not rent-controlled. Buildings constructed after 1978 are generally exempt from SF rent increase limits under the Costa-Hawkins Act.

Based on SF Assessor records. Not legal advice — confirm with the SF Rent Board.

Building characteristics
Units2
Floors2
Year built1979
Total area2,800 sq ft
Property typeMulti-Family Residential
Tax statusNone
Blocklot5611047
Ownership

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

Owner name
Robert Mittelstadt Rev Tr
Mailing address
Bean Sarah M Successor Ttee 1305 N Smith Rd Palmer AK 99645
Last sale
000000

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.

21 Prospect Ave, San Francisco, CA 94110
23 Prospect Ave, San Francisco, CA 94110
Augrented Insights
Initial analysis

The property at 21-23 Prospect Avenue is a 2-unit, 2-story multi-family residential building located in Bernal Heights, constructed in 1979 and currently owned by the Robert Mittelstadt Revocable Trust. The building has undergone significant interior improvements in recent months, with major renovation work initiated in late 2023 involving kitchen and bathroom remodels on the second floor, and substantial bedroom and bathroom modifications on the third floor, with a total estimated cost of $93,000. This was followed by a revision in early 2024 to eliminate specific structural components (PSL beams), and similar renovation work was completed in October 2023 involving electrical upgrades, plumbing improvements, and kitchen/bathroom remodeling valued at $66,000.

The property has seen consistent maintenance and improvement efforts over the years, including the installation of a rooftop solar system in 2016 (3.8 kW with 11 PV modules), and structural work completed in 2006 regarding a retaining wall replacement that involved collaboration with neighboring properties. A tenant buyout occurred in August 2023 at Unit 23 for $35,000. The building's recent history shows one fire complaint regarding illegal occupancy in October 2019, which was referred to the Department of Building Inspection. The property has experienced several parking-related issues in the vicinity, with multiple reports of abandoned vehicles and illegal parking between 2019 and 2022, though these are external to the building itself. A rent board service request was made in February 2022, which was resolved with a correction of the unit count.

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

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Risk rating

How 21-23 Prospect Ave'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
91th percentile

Out of 1276 buildings in this neighborhood, 115 are predicted to be safer.

RiskiestSafest
Predicted 12-month outcome
86%
No DBI
violation
14%
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 location

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

Neighborhood (ZIP code)

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

Building age

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

12-Month severity forecast
No violation 90.4%
Moderate concern 7.1%
Severe concern 2.5%
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

21-23 Prospect Ave event timeline

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

2025
311 Request Jun 14
Overgrown tree
other
311 RequestFeb 27
Blocking driveway cite tow

See all 9 events

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

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Every record we have

Full data for 21-23 Prospect Ave apartments

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

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