APS : Architectural Preservation Services


Riversdale House Museum

Riverdale, Maryland

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Maryland-National Capital Park and Planning Commission

Completion Date



The Riversdale House Museum is a late Georgian Mansion built in 1807 by Baron Henri Joseph Stier, a Belgian emigrant, to resemble his home in Belgium, Chateau du Mick. Baron Stier lived in the house for only a brief period before returning to Belgium. His daughter Rosalie inherited Riversdale and lived there with her husband, George Calvert, an adescendant of the Lords of Baltimore. The house remained in the Calvert family until 1887, when it was sold to a real estate syndicate. It went through several short-term owners until 1949; on this date, the mansion was acquired by its present owner, the Maryland-National Capital Park and Planning Commission.

In 1990, the eight Aquia Creek sandstone columns located on the exterior of the house were patched with restoration mortars. These repairs did not hold up well over the past two decades and were consequently in poor condition. In several areas, the patches were loose, confirmed by a hollow sound when tapped on the surface. Cracks were observed in numerous locations, and loss of patching material was also noted.


The project entailed removing the failed patching material and deteriorated stone from the columns and repatching these areas with new restoration mortars. It should be noted that the installation of the new patching material was performed to higher technical and aesthetic standards than the work done 20 years ago. A toothed chisel helped to create a rough, textured surface, which aided in the adhesion of the new patching, and feathering was avoided by creating square-cut edges. An inorganic vapor permeable mineral stain for masonry, painted to match the distinctive veining and inclusions of the stone, helped to blend the new patching with the surrounding Aquia Creek sandstone.