Abstract: A chimney moisture seal for use in combination with a chimney bounded by at least one wall of a building. The building having at least one roof having a predetermined level. The chimney having at least one end portion extending through the roof. The chimney including a veneer wall and a flue including a plurality of flue tiles coupled at a plurality of flue joints, an air space having a predetermined dimension located between said veneer wall and said flue, and a chimney cap mechanism located on said exterior end of said chimney and coupled to at least a portion of said flue and said veneer wall. The improvement being a moisture barrier structure mounted in the air space. The moisture barrier structure is positioned below the predetermined level of said roof. A method for preventing deterioration of an exterior veneer wall of a chimney structure. The method comprising mounting a moisture sealing mechanism and sealing a predetermined portion of said air space between said veneer wall and said flue.