How can I tell if I have mold in my walls?

Mold can be black, green, gray, white, or brown. Mold can even appear orange, pink or purple when it grows behind vinyl wallpaper. Another sign of visible mold is discoloration of walls, even if it has been painted over. If the water damage inside the walls persists, mold will show signs on the surface. 4014 Fox Valley Dr, Rockville, MD 20853 (301) 717-1454 http://www.mdmoldtesting.com https://www.facebook.com/MDMoldTesting/