If there’s mold outside…

Dear George,

If there is mold on the outside of the wall then is it growing on the inside? The mold color is kind of black and green and of course has grown where there has been moisture. I was wondering if you had and idea what type of mold it was?

This depends on the surface. The more porous the wall, the more moisture inside, the greater the mold growth inside the wall. The less porous, the more dry, the less growth will be inside the wall. You may be looking at mold that started on the surface and grew inward–or you may be looking at the tip of the iceberg.

There are literally thousands of known types of mold. It would be precipitous to say the mold is a certain type based simply on the color. Take a look here to start…:

https://byebyemold.com/glossary.php

and here:

https://byebyemold.com/morepix.php

What is more significant is that most types of mold secrete hydrolytic enzymes whose whole purpose is to degrade the starch and cellulose in your wall so that the mold can digest it. In nature, the mycotoxins that the mold puts out are there to discourage competition for the food source (in this case, your wall.) In your home, the mycotoxins provide the toxic element that make you sick; and the spores cause allergic reactions of varying degrees.