The concentrator at Granduc was impressive,  if only for its sheer size. The building was 240 feet wide and 442 feet in horizontal length and, in addition to concentrating facilities, also contained the general and engineering offices, the miners' dry, machine and repair shops, warehouse, receiving facilities, and laboratories.

The building was built on the side of a steep hill dipping at about a 25-degree angle and vertical difference between the top and bottom of the structure was 150 feet. Some idea of the immensity of just this part of the entire Granduc project was to be gained by the casual statistic that 10,000 cubic yards of concrete were poured for building and machinery foundations and elevated slabs within the building. It was also worth noting that while in the office section of the building no noise or vibration was evident.

One of the more important studies in design was given to the type of roof for the massive structure. Remembering that snowfall could and did reach 860 inches it was important that the roof of the building act as an immense snow slide - to avoid any build-up by shedding snow continuously. The design therefore was essentially a sandwich panel constructed of fiberglass insulation between corrugated metal sheathing heated by the natural connvection of the warm air in the building. The application of the design has proven to be eminently successful during winters of heavy snow and frigid temperatures.