Molds gradually destroy the materials on which they grow. Again, mold requires water to grow and there quite a few ways that moisture can become a problem in an indoor environment. Here is Central Texas, simple uncontrolled humidity can be a big factor. Certain moisture issues have to do with changes in the way buildings are made. For instance, structures are more tightly sealed but may lack adequate ventilation, which can cause moisture buildup. Roof leaks, landscaping and gutters that fail to guide water away from the building and unvented combustion appliances can all cause problem as well.
Mold may not always be visible. It may be growing on hidden surfaces, including the back side of drywall, wallpaper or paneling, the top of ceiling tiles and the underside of carpets and pads, etc. Walls behind furniture where condensation can form can also be a problem area. If an indoor space smells moldy or if you know there has been water damage and occupants are complaining of health issues, mold may be suspect.
A good rule of thumb for addressing moisture issues is to do so within 48 hours. If the materials in questions can be dried within this time frame, there's a good chance mold problems can be avoided. Here are a few other prevention tips: