The Folger Shakespeare Library houses the Shakespearean collection of Henry and Emily Folger. Completed in 1932 by master architect Paul Philippe Cret, the marble building expresses a stripped classicism on the exterior to blend with the classical adjacent buildings of the US Capitol Complex.

Listed on the National Register of Historic Places, the Library was in need of exterior rehabilitation—condition assessments, construction documents and construction administration were completed in order to conserve the integrity of the original façade.

Conservation—an excellent example of sustainable design—requires the reuse of materials instead of expending energy on new materials. Extensive copper staining and corrosion of structural shelf angles required careful planning to restore the building. With a goal of gentle, yet effective and efficient treatments, our team discovered a unique protocol of misting, microabrasive cleaning, and poulticing allowing deep-cleaning without damaging the stone. None of these systems worked alone; an accurate sequence was required in order to lift the stain. Specified cleaning methods reduced the water used on the building to minimize water infiltration that could affect the rare collections archived in the building.

Additionally, our team used sounding and a pachometer to locate incipient spalls at corroding shelf angles. Probes confirmed the hypothesis that some structural steel was sound, while some required replacement. With economy in mind, the design pinpointed just the corroded steel and stabilized the structure without taking entire elevations apart.