Flood waters will penetrate the wall cavities of a home and the wall materials then serve as a substrate for mold development. This study measured the effect of flooding and subsequent drying on the extent and type of mold on different residential wall materials. Wet and dry wall samples were analyzed by cloning and sequencing and twenty-one mold species were identified from above and below the water line. Real-time PCR quantitated selected species on fiberglass batt insulation, gypsum wallboard, wood stud, plywood panels, vinyl siding, and house wrap. The mold species found in the highest concentration were Aspergillus fumigatus, Paecilomyces variotii, Chaetomium globosum, and Stachybotrys chartarum. The batt insulation supported the highest concentration of mold, followed by the wood stud, sheathing and gypsum wallboard. The high level of Aspergillus fumigatus and Stachybotrys chartarum on the wall materials seven months after flooding is a cause for concern.