Recognizing that real estate informs culture, city planners have embarked on a project to preserve the historic character of the south Mission, one building at a time. Architecture, they said, is a key component of a community’s identity, and protecting it would be a boon to the socioeconomic diversity that has earned the Mission its reputation as a cultural hub.

“There’s always an interrelationship between architecture and cultural values,” said Matt Weintraub, who heads the city Planning Department’s Historic Resources Survey Team.

Weintraub and his team recently wrapped up a three-year initiative during which they identified and evaluated the historic significance of 3,787 properties. The survey covers the area from Potrero Avenue west to Guerrero Street, and 20th Street south to Cesar Chavez.

“South Mission is one of the few remaining 19th-century streetcar suburbs that are intact in San Francisco,” Weintraub said.

The 1906 earthquake and the fire that followed wreaked havoc on the Mission as far north as 20th Street. Today, the neighborhood retains buildings built as far back as the 1850s, a period of pioneer expansion. “It is unique in terms of being able to go back to the earliest, at least, U.S., settlement in San Francisco,” Weintraub said.

South Mission is one of four areas the department is evaluating as part of an effort, begun in the 1990s, to compile a comprehensive list of historic resources for the entire city.

To qualify as a historical resource, a building must be at least 50 years old and considered integral to architectural, archaeological or cultural patterns, according to criteria issued by the California Office of Historic Preservation. The city used the state and national historic registers as models for the survey’s scope.

Shotwell Street, for example, is a veritable exhibit of Gold Rush-era housing stock, and is listed as a potential historic district between 20th Street and Cesar Chavez.

“It kind of captures the whole early 19th-century history in one long linear corridor,” Weintraub said. “If there’s one particular area of the Mission that exemplifies the historic character of south Mission, I’d say it’s Shotwell Street.”

In spite of the nationwide real estate bust, the Mission’s real estate market remains strong, say local housing developers. But development could erode the quality of life for residents both present and future.

“These buildings are indicative of that quality of life,” said Alan Martinez, a member of the city’s Historic Preservation Commission, referring to homes built throughout the Mission’s evolution. “This is about preserving what people like about San Francisco and why they moved here in the first place.”

The survey follows a major systematic rezoning of San Francisco’s eastern neighborhoods, areas experiencing “a lot of development pressure,” said Planning Department preservation coordinator Tina Tam. Its findings will alert planning commissioners to the importance of individual homes and swaths of buildings that could be considered parts of a cohesive historic district.

“As a planner, that guides me to better understand what would be appropriate in terms of changes to [one] building,” Tam said. She gave an example of a homeowner proposing to put a modern facade on a 20th-century Victorian in the Mission. “As a planner, I might say that’s not appropriate for this area.”

New condos and modernist homes emerging in a part of the city billed as a center of 19th- and early 20th-century history begs the question of how such developments are coming to fruition. At a community workshop on Wednesday — the first of two meetings the Planning Department hosted to gather feedback on the survey findings — planners chalked that up to a deficiency of “context” available to them when vetting building projects.

A row of Victorian-style homes on Capp Street between 22nd and 23rd streets can potentially be classified as "historically significant."

“If you’re lacking that, you’re not necessarily coming to the most informed conclusion,” said Weintraub. The department has incorporated “additional scrutiny” into its permitting process during the past decade, he said. Planning Director John Rahaim told residents at the Wednesday workshop that his department has been “beefing up” preservation staff and expertise in the past five years.

But it’s up to property owners, not city planners, to secure historic status for their buildings. That requires acceptance into historic registers at the state or national levels.

Realtors at Vanguard Properties, a home development and marketing firm on Mission Street, point out that there are both costs and benefits to such a designation. Renovations to historic homes typically “cost twice as much and take twice as long,” said James Nunemacher, Vanguard’s broker of the month for September.

“I don’t think people mind it as much if they know what to expect, because ultimately it could be to their benefit,” said Jean-Paul Samaha, a Vanguard realtor who served for a year on the city’s Landmark Preservation Advisory Board before it became the Historic Preservation Commission in 2009.

Homeowners willing to confront more red tape stand to pay lower property taxes on historic buildings, and are eligible for grants to fund repairs and restorations if they are listed on state or national registries. Under the Mills Act of 1972, the state offers to reduce property taxes for owners who preserve, maintain and restore properties that are designated historic.

Owners have the choice to apply to the registers once planners confirm that their properties are eligible. Planning staff will announce their recommendations of eligible properties at a Historic Preservation Commission meeting on October 6.

“There can’t be a historic district without a constituency,” Martinez said. “And that’s what I want to find out — are people wanting this?”