A sealing system useful for sealing a slide out room in a recreational vehicle (RVs). The sealing system includes a first bulb seal that is adapted for being affixed to a transverse surface that defines an opening in a sidewall of the RV. A second bulb seal is affixed to a peripheral flange that extends from an end wall of the slide out room. Both of the bulb seals have an hourglass shape. The peripheral flange fits within the opening when the slide out room is in its retraced position and the bulb seals meet in a complementary fashion to form a seal. A wedge seal is included spaced inwardly on the sidewalls of the slide out room and is designed to contact the bulb seal attached to the opening when the room is extended. An internal flange is not required for sealing when the slide out room is extended.