Rule 385. Conventional building materials in partitions, floors, and ceilings may provide adequate radiation shielding for panoramic installations. When a conventional building structure does not provide adequate shielding, the shielding shall be increased by providing greater thickness of building materials or by adding lead, concrete, steel, or other suitable materials to the walls, floor, and ceiling of an existing room. Shielding shall be subject to approval by the department.
Mich. Admin. Code R. 333.5385