Abstract: The invention is an improvement in floor-standing machines for cleaning inside surfaces of buildings such as walls and ceilings. The improved machine includes a first support for supporting the apparatus in an upright orientation and a second support for supporting the apparatus in a horizontal orientation. The machine may readily be moved on the floor in the upright orientation and in dolly-like fashion and supported on the floor for use in a "face up" horizontal orientation. The machine has modular dirt-collection, cleaning solution and rinse water tanks, each of which is slidably attached to a mounting member. The tanks are readily removable for filling and/or emptying as needed. Implements such as cleaning wands and the like are conveniently stored at the side of the machine.