Arntz Builders, Inc., a Novato-based company, has received a $17.8 million contract from the County of Marin to replace the roof of the 55-year-old Marin County Civic Center.

The project is being touted by the county as one of the largest renovations undertaken on the center since it was constructed in the 1960s.Frank Lloyd Wright designed the 470,168-square-foot building. The county stated it is the largest completed public project of the architect’s career.

Listed in the National Register of Historic Places, the blue roof is among the structure’s notable features and is near Highway 101.

But it’s been deteriorating.

Dating to the original construction more than 50 years ago, the roof now has four layers of recoating and patchwork. Despite roof repair projects in 1999 and 2000, county officials state the membrane is fracturing and peeling, resulting in leaks and substantial fading of the iconic color.

The county detailed that the process will include removal of all the old material and application of a new polyurethane membrane. Officials promise the process should maintain the historic building’s look.

“We have meticulously researched and planned this project over the past two years, and we are confident that this new material is the ideal choice for this architectural landmark,” said Patrick Zuroske, Department of Public Work’s Capital Projects division manager. “This is a sizable undertaking and there’s a long road of hard work ahead.”

The project is expected to begin in spring 2018 and will initially focus on the southernmost section of the Civic Center, which consists of the Administration Wing and the library dome, and then expand to the Hall of Justice. After roofing is complete, DPW intends to refurbish the skylights as a separate project.