This Old Conservatory
Rehabilitating an American Treasure in San Francisco's Golden Gate Park

In 1995 during one of the worst winter storms on record, 100 mile-per-hour winds tore through San Francisco, leaving one of the city's most beloved landmarks in tatters. 40% of the glass tiles that once sheathed the Victorian-era Conservatory of Flowers lay smashed on the ground, and several wood arches were damaged. Inspecting the building after the storm, Department of Public Works officials despaired to find that the years of extreme moisture both inside and outside the building had rotted the infrastructure extensively. It was clear that something had to be done to save this fragile, decaying glass palace. But what?

"This was a totally unique animal," says Edgar Lopez, a project manager for the City and County of San Francisco's DPW Bureau of Architecture. "Here was this pre-fab, one-of-a-kind 19th Century greenhouse and no existing drawings. No one knew how to put the building back together." Indeed little was known about the construction of the building.

Without any substantial documentation, the rehabilitation team was not even sure the kit would come apart. The decision was made to develop a testing phase, which involved the removal and reassembly of a 900 square foot section of the West Wing. Each component was separated to determine the assembly technique, and the various building materials were analyzed to determine their age, composition and integrity. "Like a dissection," says Jim Kennedy, the project's construction manager.

When the analysis was complete, the team was faced with two key issues that would determine the course of the rehabilitation: what type of lumber to use and whether the building should be put back exactly as it was or built as it should have been.

When the three bays of the West Wing were dismantled, it became clear that the building was a hodge-podge of different types of lumber including ponderosa pine, sugar pine, Douglas fir and old-growth redwood. Except for the redwood, these were all decaying at varying rates, particularly the fir. The mullions were especially compromised at the attachment point due to rusting square nails.

The project's engineers were recommending pressure-treated new growth redwood to replace these rotted pieces, but the City was determined to find a more environmentally friendly material. In the end, a decision was made to use buckskin logs, trees that fall naturally or are abandoned by logging companies. The engineers were only willing to agree to this if each piece was hand-graded to determine its structural strength. The City brought in a pro, Charlie Jordain, who hand-graded each of the 2000 milled pieces.

Perhaps the biggest decision that the team faced in the rehabilitation project was the question of historical accuracy. In the first phase of the project when the three bays were dismantled and reassembled, the team was determined to replace everything exactly where it had been, imperfections due to structural settlement and all. But midway into the assembly, it became clear to everyone that "as it was" was not as good as "how it should be." The roofline had a wavy look and the glass was misaligned. What's more, the whole thing was off square 2 inches.

Discussions began immediately with Christina Wallace, FEMA's representative for federal oversight of preservation. Eventually a decision was agreed upon to group pieces like the mullions with their arch as opposed to replacing each in its exact, original location.

Adding to the complexity of the project was one very old philodendron. The Conservatory's century-old tropical giant could not be moved. Several other very old and valuable species also needed protection from the mayhem. So, in Phase One the team also tested temporary enclosures for the plants. The primary issue was heating. These plants would be irreparably damaged in sustained temperatures of less than 58 degrees. A fin tube heating system was devised, but concern for the plants was so high that four team members, including Kennedy, wore pagers that would start to beep if the temperature dropped below 58. Once the pagers signaled the team, they had one hour to restore the temperature in the enclosure. "It happened three times," says Kennedy, shaking his head thoughtfully.

$25 million dollars later, rehabilitation of the Conservatory is complete. "We have created plant heaven," says Lopez and adds, "I'm so proud to be a part of the rehabilitation of a landmark that is so loved by this city…to be associated with something so unique and beautiful. I still drive by on weekends and just look at it."