His experience included selecting the route of the Panama Canal and constructing the Alaska Highway during World War II. He began work for the Commission in July 1949, just before they made the decision on reconstruction. The general contractor was John McShain Inc., headed by John McShain, the "Builder of Washington" who had constructed (amongst other works) the Jefferson Memorial, the Pentagon, and the FDR Library at Hyde Park. McShain's on-site construction manager was Paul Hauck, who had also been in charge of the Pentagon project. The scope of the project involved the complete removal of the interior of the White House, except for the Third Floor, and included salvage and storage of critical interior elements, excavation of new basement levels, and construction of new foundations, steel and concrete structure, masonry interior walls with plaster finish and wood paneling, custom plaster moldings, refurbished and replacement windows, and new heating, ventilation, air conditioning, plumbing, electrical, and communications systems. The bulk of the work was to be accomplished within the exterior stone walls which were to be kept in place and repainted. Landscaping around the house was to be replaced. All workers were subjected to security clearance by the Secret Service. The West Wing was to be kept fully operational and occupied by the president and his staff. All work was to be completed for a total cost of $5.4 million and completed by late 1951 (in 660 days, approximately 22 months). The rooms of the State Floor were reconstructed with few significant changes. The Second Floor rooms were adjusted to provide built-in closets and additional bathrooms, but otherwise were rebuilt largely as they had been. The Third Floor was expanded and the rooftop solarium replaced. Two new basement levels were added under the Ground Floor. The most noticeable change to the State Floor was revising the Grand Stair to discharge eastward into the Entrance Hall to provide a more ceremonial procession from the upstairs. The opening to the south was kept with a railing providing a balcony-type overview into the Cross Hall. On the Second Floor, the rooms above the East Room were lowered due to a thinner (yet stronger) steel floor structure. This allowed access from the Central Hall via a short ramp in a central passageway that was narrowed to accommodate an additional service stair and added closets. Additions to the Ground Floor included additional service elevators to service the upper floors, a bowling alley, expanded kitchen, broadcast studio, barber shop, medical and dental clinics, carpentry and upholstery shops, and large service and equipment spaces.