Points of moisture ingress differ based on the employed exterior building system. Construction joints are the most probable areas of moisture intrusion and they should be routinely inspected for openings and/or material separation from the substrate. Preventive measures at construction joints should include proper repair to all openings and irregularities. Repairs are typically completed with construction sealants. Proper repair methods of sealants require the full removal of the existing sealant and thorough joint preparation prior to the application of the new sealant. In most instances, applying sealant over existing sealant only contributes to further material deterioration.
Materials high in porosity, such as brick, concrete, limestone, etc., are also vulnerable to moisture infiltration. The porosity of masonry materials make them permeable to moisture because their interior structures are made up of interconnected pores and capillaries. Moisture in its liquid state flows through these passageways from capillary action (suction). The volume of moisture flow depends on pore sizes and capillary structures.