Microbial organisms are ubiquitous in every environment, including built environments. However, our understanding of the environmental conditions impacting microbial growth and diversity in the BE is still largely based on observational studies. In this study, we use an experimental approach to test how site productivity and disruption affect bacterial and fungal communities within the built environment. Specifically, we determined how deferential moisture conditions, constant humidity vs. wet-dry cycling, impacted growth and diversity of microbial communities on three common building materials: gypsum drywall, medium-density fiberboard (MDF), and oriented strand board (OSB). Microbial growth was measured using culture-independent microscopic cell counting of bacteria cells, and spore counting and hyphae length measurements for fungi. Community composition was determined via bioinformatic analysis of amplicon sequencing libraries for bacteria (16S) and fungi (ITS). Moisture availability had significant effects on growth for both fungal and bacterial communities. Bacterial growth was generally lower when dry periods were introduced compared to the materials that were kept wet, especially in the later time points in the study (Days 35 and 47). This same pattern was also observed in fungal spore counts and hyphae length. Despite moisture affecting growth in both bacteria and fungi, ATP was not significantly affected by moisture availability. Interestingly, the hyphae length was significantly lower on MDF compared to the other two materials. In addition to growth, moisture availability also impacted fungal and bacterial diversity. While moisture only impacted alpha diversity in terms of bacterial evenness, beta diversity was significantly different between treatment types for both bacteria and fungi. While fungal alpha diversity was not affected by moisture availability, it was significantly impacted by material type and time point. Additionally, bacterial phylogenetic diversity was affected by Day.