A structural face-lift planned for the 215-year-old in the Los Rios Historic District is intended to keep it from collapsing in a major earthquake.
In as soon as six months, wood frame additions from the early to mid-20th century will be removed. The additions, the San Juan Capistrano Historical Society says, are making the adobe unstable and are of no historical importance.
"If we have another earthquake of anywhere over 6, we're probably going to lose one end of that building, and it would be a catastrophic loss," said historical society President Tom Ostensen.
The additions will be removed, and a west-facing porch will be constructed with a retaining wall to support it. Once the rehab—which also will include the addition of a porch and a new, red cedar-shingled roof—is finished, the adobe will house Native American artifacts from the mission period.
The historical society won approval Tuesday from the city's Cultural Heritage Commission to go forward with the retrofits.
According to Ostensen, who spoke to Patch via telephone Wednesday afternoon while watering plants on the adobe property—also home to the blue Victorian, the O'Neill Museum—numerous locals were actually born in the Silvas Adobe.
"There were no hospitals back then, you know," he said, "only midwives." Ostensen said the historical society will share with the public bits of the adobe's history as the construction progresses.
Records from the 1936 Works Progress Administration's adobe survey project in Orange County indicate that the Silvas Adobe at one time had a porch on the rear, which was partially enclosed by the 1930s. Thus, the historical society will add a west-facing porch to the rear of the structure.
San Juan Capistrano's historic preservation manager, Teri Delcamp, has suggested that the historical society alter some of its plans: the roof should be built of redwood singles, not red cedar, and the outside plaster should be painted white, not green, she said.
Both cedar and redwood were historically used, but the redwood was more common in the region. There is evidence that redwood forests were discovered by Gaspar de Portolá and that that wood was being shipped from the Bay Area to San Diego as early as 1776.
The historical society "should consider the use of redwood shingles instead of cedar as a more historically common roofing material unless there is evidence that the Silvas Adobe had a cedar roof in the late 1800s," Delcamp wrote in a report.
The Cultural Heritage Commission and Delcamp are also recommending that the historical society scrap its plans to lay a new concrete floor of the front porch and to use wood instead. "The concrete was installed in the mid-20th century, well after the restoration period," Delcamp said.
The historical society will be aided in its retrofit efforts by Roy Tolles, renowned in California for his expertise in making old adobes fit to withstand earthquakes.
Ostensen expects the project to take six months. He plans to apply to the city for demolition permits as soon as August.
In the meantime, the historical society will focus on raising funds. Anyone who wishes to donate should mail a check to the historical society (the money will be set aside in a restricted account, Ostensen said).