Lamb designed the windows to be attached to the exterior walls using thin metal brackets instead of being set back into stone frames. The windows were thus flush against the exterior walls - not recessed by three or four inches, as on most buildings up to that time. These recesses tended to cast shadows and give buildings the look of immense waffle irons. About the only creatures who missed these ledges were the pigeons. Constructing windows in this way also made more rentable floor space available, increasing the profit margin of the building.
In his design Lamb achieved an innovation on the interior of the building as well. He was able to mount the radiators inside the walls, thus keeping them out of sight (and away from valuable floor space).
In addition, this approach made it possible to reduce the thickness of masonry skin. Not more than half the weight of materials usually required for walls containing inset windows was used. The frames around the windows were made of aluminum [G 14 / spandrels] instead of masonry. The building was thus lighter, cheaper and quicker to build. Caulking around the windows had to withstand extreme temperatures with a range of about 200 degrees.
