Rubba-Roof can provide a guaranteed method for the refinishing and repair of leaking metal roofs. The Rubba-Roof compound has high adhesion to metal and will seal old fixing holes and rusted overlaps.his article explains how to fix a leaking metal roof with Rubba-Roof. Metal roof sheeting takes two main forms. One is the older style of small profile, corrugated ‘tin’ that has been used for nearly two centuries as an economical roof covering for agricultural buildings and rustic dwellings.