a mounting assembly including a housing for a roller operated system , such as a projection screen system , which facilitates installation in a building in stages to reduce the risk of damage to system components . the housing includes longitudinally extending lipped projections along its top wall . attachment lugs of brackets that support the roller on which a sheet , such as a projection screen , is windable are adapted to engage the lipped projections and enable the brackets to be mounted to the housing at selected longitudinal locations to allow for positioning adjustments of the roller . the vertical side walls of the housing also are each constructed with a projecting lip adapted to engage an upstanding hook of the bottom closure panel to thereby enable the closure panel to be mounted to either of the side walls of the housing . a method of installing a roller operated system is also disclosed .