Abstract: Thin gage pre-creased and pre-punched sheet aluminum is cut to length from a supply roll on the job site where light fixtures are recessed in a ceiling containing combustible insulating material. The thin sheet metal is readily formed into a guard or dam of the necessary size and shape and placed around the recessed light fixture to prevent the insulation material from coming into contact therewith. Bendable tabs along one edge of the sheet material form bottom anchoring elements on the guard which can be stapled to the ceiling structure. The guard or dam is held in its erected form by screws or other fasteners engaging in the pre-punched openings of the sheet material. The guard is open from top to bottom and a generous air space is provided between the side wall of the guard and the light fixture.