Mold needs moisture to grow, so less humid states should be the least likely places you would find mold – right? Not so fast. The rankings are NOT based on hurricane or flood damage, inferior building materials, “tight” construction, or humidity.
10 LEAST Likely States to Find Mold
- West Virginia
Out of these states, Colorado is really the only one located in a desert climate where you might expect mold to be rare. States from the humid Midwest, New England area and Southern US don’t seem like they belong on this list.
10 MOST Likely States to Find Mold
- South Carolina
- South Dakota
Maybe you can get on board with notoriously humid states such as Florida and South Carolina having the highest mold rates, but Arizona and Nevada have some of the lowest humidity levels in the country! What’s going on here?
Building Materials and Practices Play a Key Role
It seems ironic that a home in Phoenix or Reno could be at a higher risk of mold than one in Montgomery or Chicago, but once you realize climate has little to do with indoor mold growth, it’s easy to understand. After all, today’s homes are built tightly to improve energy efficiency, but in the process, moisture has nowhere to go.
Picture a glass of ice-cold water sitting outside on a 90-degree day. Condensation quickly forms on the cold glass surface and drips down the side. Condensation forms inside tightly constructed homes as well, but the water becomes trapped, building up inside wall cavities and creating the perfect environment for mold to grow.
The moral of the story: it doesn’t have to be humid outside to be humid within your walls. In fact, of some 32,000 San Diego homes inspected for defects each year, about 41% of single-family homes and 23% of multifamily properties have problems with the building envelope that encourage mold growth.