Abstract: An enclosure for use in conjunction with a recessed ceiling fixture is provided which includes a substantially rectangular housing defining a top wall and side walls constructed from a single piece of fire-resistant gypsum wallboard. The housing is fastened to continuous stamped metal support flange depend inwardly from bottom edges of side walls of the housing to facilitate mounting of the housing between spaced apart building joists. The recessed fixture is mounted to the interior of the support flange after installation of the housing between the building joists.