The Spaulding-Sidway Boathouse is a Late Victorian Stick / Queen Anne style frame structure constructed in 1870.

The boathouse is a two-story frame structure, clad in clapboard, on concrete piers.

Between 1935 and 1940, to save the boathouse from demolition when the Spaulding estate was acquired in order to become Beaver Island State Park, neighboring property owner Frank St. John Sidway, a grandson of Spaulding, moved it about 270 feet northwest to his land.

[2] The building is a rare surviving example of a small boathouse used primarily for storage and social activities and is reflective of Grand Island's importance as a seasonal recreational area in the 1800s.

The boathouse has been continuously used for light boat storage and social activities since it was built, and although many boathouses on Grand Island have fallen victim to weather, it stands today virtually as built and is now a part of a private residence.