History and Significance
The Conservatory of Flowers, originally completed in 1878, is one of San Francisco’s most noteworthy historical and cultural resources. Surviving the 1906 earthquake, the Conservatory is the oldest building in Golden Gate Park and the oldest public greenhouse in California. It is listed on the National Register of Historic Places and the California Register of Historic Places, and is also a city and county landmark of San Francisco. The American Society of Civil Engineers formally recognized its innovative structural system, designating the building as a Historic Civil Engineering Landmark.
Project Summary
In December 1995, a series of storms severely damaged the Conservatory of Flowers and forced its closure. Although deferred maintenance contributed to the deterioration of its wood structural members and glass skin, the storm damage provided the opportunity to completely restore and adaptively use the landmark greenhouse. The project was complicated by the need to relocate the existing plants and the preparation of a temporary, in-situ greenhouse for several large historic specimens that could not be moved. The six-year effort, which entailed the conservation, restoration, and rehabilitation of the conservatory, included lateral strengthening and new mechanical and electrical systems. The client wished to expand the educational component as well. The new interpretive exhibits, combined with enhanced visitor accommodations, including restroom facilities, resulted in a facility much better equipped to educate and serve the visiting public. The conservatory reopened to the public in September 2003.
Description of Work
The restoration process included the complete integration of preservation architecture, planning, and conservation work, as well as the complex technical planning and agency review process.
Historic Structure Report (HSR)
The production of this report included an extensive research and documentation phase that clarified the building’s history and construction chronology. In addition, the report presented the results of the architectural, structural, and material conditions assessments, with specific recommendations for repair and restoration. The report provided schematic designs for the restoration scheme, involving disassembly and partial replacement of deteriorated wood members, as well as an overall building system and code upgrade.
Integrated Team Approach
Based on recommendations in the HSR, the project team developed designs for rehabilitation, addressing the building’s structural HVAC, code, and accessibility deficiencies. The original structure did not have a complete structural load path for carrying lateral forces. The architect and structural engineer collaborated on a strengthening solution that would maintain the structure’s delicate quality. Carefully detailed new steel and wood elements include a new system of concealed stainless steel reinforcement plates, as well as exposed steel trusses with ¾-inch diameter cross-bracing rods that complement the lightness of the building.
The HVAC solutions involved the creative insertion of new automated environmental control systems located in trenches below the interior pathways; these heating, ventilation, and fogging systems simulate different environments in each of the building’s three wings. The hot and humid conditions of a working greenhouse caused deterioration of the original wood elements. The conservatory’s 100 wood arches are actually assemblies of several pieces of wood connected with elegant scarf joints. The rehabilitation method combined treatment and reuse of original components with replacement parts. In keeping with the client’s desire for sustainable building practices and materials, reclaimed old-growth redwood was used to match the original material, instead of new lumber. Elegant accessibility design solutions involved sloping floors to connect different levels in the building without requiring handrails or other visually disruptive elements. All rehabilitation efforts were in accordance with the Secretary of the Interior’s Standards for the Treatment of Historic Properties.
The project architect worked closely with the landscape architect to create a new master plan for the conservatory’s site. The plan addressed back-of-house support spaces, new interpretive exhibits, new freestanding restrooms, and future expansion. The project also included presenting the design solutions to the Federal Emergency Management Agency and the State Historic Preservation Office for review and approvals, as well as at public meetings for community members and fund-raising events.
Project Results
The Conservatory of Flowers project is an excellent example of an integrated restoration effort that involved extensive research, documentation, conservation, and innovative architectural design solutions for a prominent cultural resource.
