Portfolio: Project Details
Coit Tower
Historic Restoration and Rehabilitation
San Francisco, CA
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Coit Tower, the beloved San Francisco landmark, is one of the City's most
architecturally significant public buildings, known for its controversial
seven-story towering design, its prominent placement on historic Telegraph Hill
in 1933, and for its series of Diego Rivera-inspired frescoes depicting "Life
in California" on the interior walls.
Aside from routine maintenance, Coit Tower had received little conservation
attention during its first fifty years. In the mid 1970's, the City and County
of San Francisco, concerned about continuing deterioration and spalling of the
concrete surface and its inability to stop water penetration from damaging the
murals and frescoes in the lobby, attempted unsuccessfully to patch
deteriorated exterior concrete and to arrest the leaks by installing additional
layers of roofing material, only to further exacerbate the leakage because of
trapped water. In 1984, the City decided to work with expert consultants to
correct the spalling and water problems and save the murals, and hired
Interactive Resources to investigate the landmark, document the extent and
causes of deterioration, and restore the tower to its original condition.
Our investigation included a field survey of the walls, retaining walls,
planters, sidewalks, and stairways associated with the monument. We
found advanced deterioration due to the harsh marine environment and
inadequate concrete cover. We recorded this deterioration in the form of
sketches and photographs, which were later presented in a detailed report.
Cracks occurred at a variety of locations throughout the tower, which were both
unattractive and a potential source of further deterioration if not properly
repaired. Spalling was another serious problem; corroded reinforcement and
delaminated concrete were fully exposed.
On the basis of our report, the City decided to move forward with complete
restoration plans for the tower. We developed a program to restore the
integrity and beauty of the structure and stop water infiltration into the
tower lobby. New materials were carefully specified to duplicate the original
materials in strength, composition, color, and texture.
An unusual aspect of the project was the controversy over the monument's surface
coating. There were many local and State agencies involved in the restoration
approval process, each of which held varying opinions as to whether the new
coating should duplicate the color and texture of the tower at its original
1933 appearance, or to give it the "weathered look" characteristic of the
existing condition. A series of samples of the of the existing coating were
taken from various parts of the monument, and analyzed for color, porosity, and
reflectance, and consensus was reached on the issues of color and texture. The
selected coating also had to be physically compatible with the existing
material. After many hours of investigation and research, and numerous
presentations to the various agencies, the "perfect" surface coating was found.
The restoration work on the exterior of the tower was completed in November
1988. An Art Conservator completed restoration of the murals early in
1989, and the tower was reopened on July 18, 1990 to the public following the
installation of protective barriers.
Coit Tower is heavily visited year round and is very important to the
City's tourism industry; therefore, we developed a plan that enabled the
landmark to remain open throughout most of the entire restoration.
