Rock Island Historic Buildings

Project Background

Rock Island is a wooded island off the tip of Wisconsin’s Door Peninsula at the mouth of Green Bay in Door County, Wisconsin. The uninhabited island is approximately 1.6 miles long and 1.1 miles wide and is almost entirely owned by the Wisconsin Department of Natural Resources, which maintains Rock Island State Park. The ten historic buildings on this island were built by Icelandic inventor, Chester Thordarson as part of his summer estate in 1910, and are listed as part of the Thordarson Estate Historic District (NHRP # 85000641). The buildings were uniquely laid with Lake Superior limestone, many with washed, rounded field stones by Icelandic crafts people. They were in need of restoration work to manage some deferred and ongoing maintenance needs.


Performed a detailed condition investigation of seven masonry buildings with clay tile roofs

Evaluated the structural systems and monitored for movement

Exterior envelope maintenance repairs of masonry, wood components, windows, and roof.

3D Rendering for clear understanding of the extent of work

Contractor pre-qualification services

Navigating a project in a remote location with limited accessibility and infrastructure

Worked with WI SHPO to meet the requirements of the Secretary of Interior Standards for Restoration.


This project identified the unique character for the seven masonry buildings and developed specialized treatments for each. Treatments ranged from repointing, stone repairs and water-table, sill replacements, structural wood repairs, painting, wood window restoration, and clay tile roof repairs in order for these structures to endure this next cycle of repair. Contractor pre-qualification services were provided to maintain a high integrity of work for a historic structure.

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Unique character and specialized treatments developed for the seven buildings 

Exterior envelope work of rounded, Lake Superior Limestone 

Navigating a project in a remote location with limited accessibility and infrastructure 

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