Basically, mold needs four things to grow and thrive:

    Mold spores are ubiquitous; they are found both indoors and outdoors. Mold spores are like seeds that can be found floating through the air and in settled dust. Mold spores cannot be eliminated from indoor environments.
    Mold spores thrive in temperatures 32 and 120 degrees Fahrenheit. Temperatures from about 70 – 90 degrees are the most conducive for mold growth. Mold doesn’t die when temperatures drop below 32 degrees, they lay dormant until temperatures raise, or they are set out to warm up.
  3. FOOD
    Mold grows well on, and feeds on, organic materials such as paper products, cardboard, ceiling tiles, and wood products. Mold can also grow in dust, paints, wallpaper, insulation, drywall, carpet, fabric, and upholstery. 
    Mold growth in an indoor environment is typically related to water or moisture exposure, flooding, leaky roofs, building-maintenance or indoor-plumbing problems. Mold growth can also be triggered by excessive condensation or lack of ventilation.

The spores are everywhere, mold likes the temperatures that humans like, and literally the whole hous is food source for mold. The only thing that can be managed and controlled is MOISTURE.

Simple logic tells us that the only way to combat mold is to combat #4 above - moisture. 

During our inspections we have come across various culprits that caused mold growth. Some culprits we found include leaky crawlspace, faulty surface drainage, deficient ventilation, faulty humidistat, non-functional ventilator, bathroom leak, washing machine leak, and other interesting scenarios. The common thread in all culprits is moisture.

Long story short, leakages (visible & invisible) and mismanaged moisture control is what must be tracked and fixed if mold problems are to be eliminated. This is easier said than done, because it needs a good understanding of building science, structural components and the building envelope.

One word of caution. If your see, smell or suspect mold, call for a diagnostic inspection that will reveal the culprits. There is no point in removing mold before a diagnostic inspection. If the culprits are not fixed, mold can return in as little as 24 hours!