Title
City Hall Roof Issues
Memorandum
In April, 2007, staff began a study of the roof structures on the City Hall building because of deteriorating conditions and water leaks. This memorandum is an update to that review process. There are two roofing structures to address. These are the main building roof, located above the 6th and 7th (mechanical penthouse) floors, and the promenade deck, which acts as the roof for the 1st floor. While the replacement of both roof structures is necessary, the timing and method of this work has been difficult to establish because of the fluidity of the master plan and the conceptual design process related to the site renovation project.
Main Building Roof
The overall condition of this roof is poor and replacement is necessary. This roof is less affected by the changes being proposed for the Courts/PD facility and the renovations to the Larcom Building. Replacement should be planned for FY 10 or FY 11, possibly in conjunction with other work being done on the site. The City may wish to consider a ‘green’ roof system or utilize this roof as a collector for stormwater that can be reused throughout the site. Interior roof drains and piping should also be upgraded at the time of replacement. Additionally, the portion of this roof that is above the 7th floor (mechanical penthouse) should not be replaced until the asbestos has been abated from the 7th floor ceiling. Roof replacement over the 7th floor would significantly disturb the asbestos material sprayed on the ceiling. Since the asbestos on the 6th floor has already been abated, this is not an issue for that portion of the roof. Water leaks from this roof are not as severe as the promenade deck and can be minimized on a short-term basis through patching.
Promenade Deck
The promenade deck, which acts as the roof for the first floor, is in very poor condition. The appropriate repair of this surface will be at significant cost and a sizeable undertaking. Much of ...
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