1st Place, Historic
During the latter part of the 19th century and the early part of the 20th, it was common practice for cities to host world-class exhibitions showcasing new technologies and innovations. The 1893 Columbian Exhibition in Chicago introduced the Ferris Wheel while the 1904 St. Louis World’s Fair gave us the ice cream cone.
Most major exhibitions at that time were held in the eastern U.S., but western cities were eager to hold their own. San Diego answered the call in 1915 by hosting the Panama-California Exhibition in Balboa Park. Although the event was only a mild financial success, its legacy lives on in several structures built specifically for the exhibition—one of which is the Botanical Building, still among the largest wood-lath structures in the world.
Over the years, the structure underwent numerous changes, including modifications and reinforcements for another exposition in 1935 and further renovations in 1957.
HISTORIC: Original 1915 Botanical Building 
After restoration of the stucco, windows, steel structure and redwood lath. 
BEFORE: 2019 building before renovations to restore to original design. 
What was originally expected to be a partial wood-lath replacement became a complete replacement of all wood and roughly 1,300 repairs to the steel structure. The intricate details of the steel structure can be seen under the cupola. 
Restored large doors on west and east ends. 
As part of pre-construction work, EC Constructors’ team salvaged approximately 130 plant species of note for replanting in the building. 
The 2,000-pound copper steeple and dome cupola were restored. 
South elevation drawing 
Site plan 
Floor plan
PHOTOS: Pablo Mason Photography; BEFORE/HISTORIC PHOTOS and DRAWINGS: courtesy Platt/Whitelaw Architects Inc.
By 2016, however, the building had been significantly altered and neglected. A local non-profit, Forever Balboa Park, led the charge to have it restored. Securing an $8 million grant, the organization commissioned initial bridging and program documents to define a vision for the Botanical Building’s future. The project was moving forward but was later turned over to the City of San Diego for the next phase and execution.
The City then issued an RFQ for interested firms to demonstrate their qualifications. Platt/Whitelaw Architects Inc. and EC Constructors had longstanding relationships with the City of San Diego and a strong reputation for delivering complex projects. In 2020, the team was shortlisted alongside two others to submit an RFP. Through a competitive selection process, the Platt/Whitelaw Architects and EC Constructors team was chosen to move forward.
Teamwork Makes the Dream Work
Recalling the condition of the structure at the start of the project, Sandra Gramley, AIA, retired president of Platt/Whitelaw Architects, remarks: “It was bad. If you look at historic photos of the building, there’s a pink arched arcade that surrounds it—that was gone. The east and west façades had been redone. The only thing left was the lath roof and the steel structure. Almost all the redwood lath had deteriorated. A lot of the building had been stripped away or replaced with non-historic elements.”
Jim Summers, owner of EC Constructors, adds: “In 1957 there was a major reconstruction of the building. It’s not clear how much steel repair was done, but historic photos suggest most of the wood lath was replaced then. We suspect the curved truss bases had been rotting out at that time; they encased the bottom 6 feet of the trusses in concrete, likely as reinforcement.”
The facility also was replanted in 1957 but, over the years, it became significantly overgrown. “In 2022, as
part of the pre-construction work, our team salvaged approximately 130 plant species of note or large size for replanting that the City wished to retain,” Summers says. Once the interior was cleared, the structural engineer could bring in equipment to fully evaluate the structure.
The engineer’s findings revealed the building had deteriorated more than anticipated. “What was originally expected to be a partial wood-lath replacement became a complete replacement of all wood and roughly 1,300 repairs to the steel structure,” Summers explains. “Most of the deterioration was at the wood-to-steel connections where moisture had been trapped, causing corrosion in both materials.” The team also decided to restore the original look of the truss bases, removing the encased concrete and repairing the steel beneath.
Fortunately, the design team had excellent historical records to reference. “We had the original 1915 drawings from Carleton Winslow, the original architect,” Gramley notes. “The City had some drawings in its archive, but the San Diego History Center had many historical drawings and photographs that they were able to reproduce at a higher quality. Back in those days, a complete set of drawings was eight or nine pages; today we’d have 250 or more. There was some detailing, but it was largely up to the craftsman to interpret and fill in the missing blanks.”
The design phase lasted five months in 2021, accelerated by a strong collaborative effort with the City of San Diego. “I give the City a lot of credit,” Gramley says. “They were very proactive in getting issues resolved. It helped us avoid getting bogged down in plan checks for months. Everyone on the design team—and the City—was eager to see this project move forward swiftly.”
Challenges and Opportunities
An unexpected challenge arose from a massive Morton Bay fig tree planted at the northeast corner of the building. Over the years, it had swelled the ground and interfered with the proposed design. The team modified the footings and building design to preserve the tree as part of the site’s living history.
Another surprise was the lack of uniformity in the structure’s connection details. “We’ve benefited a lot from repetition and standardization in modern construction,” Summers says. “Back in that era, everything was slightly different, which added complexity because every connector piece was unique.”
Despite the challenges and unanticipated deterioration, the $28 million reconstruction project reopened to the public in December 2024—just in time for the annual December Nights Festival. “One of the most rewarding aspects of the project was that our own carpenter employees performed most of the carpentry work,” Summers states. “It was incredibly satisfying to see them develop new skills and take pride in this remarkable restoration.”
Judge’s Comment
A sensitive and beautiful rehabilitation of a very unique structure. The required interventions were done seamlessly. Kudos to the design team!
Andrew C. Smith, AIA, principal, Hennebery Eddy Architects
Retrofit Team
Architect of Record: Platt/Whitelaw Architects Inc.
Design-build Contractor: EC Constructors
Landscape Architect: Estrada Land Planning
Historic Architect: Milford Wayne Donaldson, FAIA, (916) 532-8004
Structural Engineer, Framing: AB Court & Associates
Structural Engineer, Steel: Degenkolb
MEP Engineer: Turpin & Rattan Engineering Inc.
Horticulturist: Waterwise Gardener
Historic Windows and Doors Specialty Contractor: Spectra
Materials
Historic Arched Windows Glazing: Guardian Glass
Storefront North Addition: OldCastle BuildingEnvelope (Glazing) and Arcadia (Aluminum)
Wood Lath Stain: Sherwin-Williams
Steel Coatings: Amershield from PPG
Surfaces: Durcon
Quarry Tile: Spec Ceramics
Floor Drains: Urban Accessories
