Why has the asthma rate in America tripled over the last 20 years? The answer is that there is now more mold in American homes than ever before. Air-tight design, insulation and cheap organic building materials have made new homes more prone to mold than old homes – and the public is just now becoming aware of these mistakes.

When you think of a musty, moldy home you might think of your grandma’s 100-year-old house in the country. But this is a common misconception – new homes not old homes – are actually often more moldy. While it’s true that old homes are more susceptible to disrepair, such as old leaks, and this causes mold, new homes have far greater contributing factors to mold growth.

About 20 to 30 years ago, America endured an energy crisis in which it responded by designing new homes with air-tight structures in order to preserve energy. Indeed this worked, but probably too well. Homes have been built so air-tight that air-conditioning and heating systems often re-circulate air that has been contaminated with moisture and mold spores and other microorganisms. These contaminants are distributed throughout the building where they fester in dark, damp places – spreading mold everywhere and reducing indoor air quality.

Insulation also helps to keep the indoor air in new homes separated from the outdoor climate to save on energy consumption. Unfortunately as a side effect, this insulation also traps moisture resulting from everyday household activities like bathing, cooking, and cleaning. Damp insulation creates a habitat for microbial growth.

Another factor that contributes to mold growth in new buildings is the cheaper building materials used. These materials are often organic, which is precisely what mold feeds on. Gypsum board and oriented strand board are used more often now. So-called “fake stucco” is an especially tasty treat for mold.

Joe Lstiburek, a Massachusetts-based building design expert, agrees that new homes are often moldier than old homes. “We used to have plaster,” says Lstiburek. “It’s drywall now. It’s paper. Mold loves paper. And we’re putting it on the outside now.”

As Listiburek succinctly puts it: “We’ve gone from rocks and sticks to paper. Even the dumbest of the Three Little Pigs didn’t build a house out of paper.”

Tagged as: air-conditioning, Air-tight, bathing, cooking, design expert, drywall, energy crisis, EPA, habitat, home, house, household, Joe Lstiburek, microbial growth, mold, mold growth, new buildings, new homes