Napa Mill Silo Structural Strengthening - Downtown Napa, Ca 
 

Rising from the heart of the Hatt/Napa Mill complex—once the industrial engine of Main Street in the late 1800s and early 1900s—two 65-foot concrete grain silos anchor a site listed on the National Register of Historic Places. With the river and rail corridor at its doorstep, this riverfront district handled everything from coal and grain to wine; later generations adapted the mill for new uses that today include the Napa River Inn and a lively public market. Preserving the silos maintains a tangible link between Napa’s working waterfront past and its contemporary riverfront revitalization.

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Treeline Construction served as Prime Contractor for the structural and seismic strengthening of the two historic silos located within the active hotel and market campus. Our work included structural retrofits to the silo shells, targeted repairs to improve lateral performance, and careful integration with surrounding occupied spaces to maintain public access and safety throughout construction.

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Beyond the silos themselves, Treeline reconstructed the walls and roof of the larger adjoining building, completed finish work within, and fabricated historically accurate doors and windows to match the original profiles—respecting the district’s architectural language while meeting current code and performance requirements.

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Executed in a high-visibility setting with tight site logistics, the project balanced heritage conservation with modern life-safety. The result extends the service life of a signature industrial artifact and sustains the historic character that defines the Hatt/Napa Mill waterfront.