Abstract: A blast room floor construction is disclosed, and the preferred and illustrated embodiment incorporates an overhead grate of substantial strength to enable a workman and work materials to be located thereon. The blast cleaning procedure forms a cloud of dust and residue which falls through the grate. Therebelow, multiple pieces are utilized to construct sloping, parallel sidewalls which form valleys. In each valley, there is located a hollow, rectangular vacuum tube. Vacuum is pulled through the tube. It has a number of holes formed in the tube which enable the sand and blast residue to flow through the holes into the tube, which are carried away for reuse. The valley is defined by adjacent sides of angle plate material. In addition, a diamond shaped sheet is folded across a diameter to define a pair of funnel surfaces where the diamond shape having notches formed in opposite corners to fit over the tube to carry the granular materials toward the hole in the tube.