The original Oxon hill manor was constructed in 1710-1711 and burned down in 1895. The remains of the structure can still be seen on the 245 acres, where the new structure resides. This location was the final resting place for John Hanson, recognized under the Articles of Confederation, as President of the United States during the years of 1781 to 1782. In 1929, a new neo Georgian mansion was built for Sumner Welles, former Under Secretary of State for Franklin D. Roosevelt.

WEI executed a comprehensive restoration of the estate’s double casement windows and French doors, preserving original assemblies wherever feasible and repairing sash, frame, and hardware components using traditional conservation techniques. As part of this scope, WEI designed and installed historically appropriate espagnolette sash locking hardware fabricated in polished brass. All espagnolette sizes, configurations, and operating functions were customized to suit the specific dimensions and operational requirements of each window and French door, presenting a unique challenge in balancing historic replication with modern functional performance. Because the original cast ornaments were heavily damaged, WEI resculpted the scrolls and shields using the originals as a model and matching the decorative paint work. This work required careful coordination to accurately reproduce historic character and detailing while ensuring reliable operation consistent with contemporary use, all without compromising the architectural integrity of the building.