Abstract: An air-conditioning condensate drainage system for mounting to the roof membrane of the roof structure of buildings or for construction thereof directly onto the roof membrane of a building structure. The air-conditioning condensate drainage system is defined by one or more strips of material having an isolation membrane having a bottom surface for assembly to a roof membrane. A pair of spaced ridge elements project upwardly from the isolation membrane and cooperate with the isolation membrane to define an air-conditioning condensate drainage channel. In the alternative, ridge strips may be disposed in spaced relation and fixed directly to a roof membrane to define condensate drain channels along the roof membrane to in-roof drains. The condensate drain strip or ridge strips may be molded or extruded and maybe formed directly on and adhered to or fixed to the roof membrane to define the condensate drain channels.