570-572 21st Ave, San Francisco, CA 94121

The two-unit residential building at 570-572 21st Avenue in San Francisco's Central Richmond district is a two-story flats and duplex structure owned by the Paul Chang Yuen Bypass Trust, which dates back to 1931.

The property's documented maintenance history shows two significant exterior improvement projects: in 1989, approximately 200 square feet of restucco work was completed on the lower front portion of the building, and in 1984, a comprehensive window upgrade was performed with the installation of forty-three aluminum windows in existing frames.

Both projects were successfully completed, demonstrating the property's ongoing maintenance and modernization efforts. However, it's worth noting that these improvements are now several decades old, with the most recent being over 30 years ago, and there are no recorded permits or major renovations in the past three decades, suggesting a period of relative stability in the building's exterior condition since the late 1980s.