451-453 20th Ave, San Francisco, CA 94121

The property at 451-453 20th Avenue is a two-unit, two-story multi-family residential building located in the Central Richmond neighborhood, constructed in 1914. The building has undergone several significant changes over the years, with the most pressing current issue being the active violation case from 2021 regarding unauthorized dwelling units in the ground floor, each equipped with a full kitchen, bathroom, and bedroom. This violation, initiated in May 2021, remains active as of the latest records.

The property has a history of unauthorized modifications and permit violations, including a 2020 incident involving unpermitted siding replacement work (approximately 900 square feet) at the rear of the building. Several permitted improvements have been made over the years, including a major horizontal addition completed in 1998 and various interior remodels in 1987. Recent infrastructure maintenance includes the replacement of a sidewalk trap in 2011 and electrical system upgrades in 2007. The building's recent history shows multiple tenant-related issues, including a tenant buyout recorded at 455 20th Avenue in January 2025.

The property has experienced recurrent issues with parking violations and street-related concerns, as evidenced by numerous 311 calls between 2022 and 2024, primarily regarding blocked driveways and illegal parking. A damaged tree was reported and documented in September 2023. The current status of the pending unit legalization permit (under review) suggests ongoing efforts to address historical permit violations, though this process has been extended over multiple years. While the building has maintained basic structural integrity and completed several improvements, the recurring issues with unauthorized units and parking violations indicate ongoing challenges with property management and compliance with local regulations.