Residential waterproofing is very important, because the mold that can grow inside the walls if they get wet can be really dangerous to the health of the residents. My friend and her young daughter stayed sick for months before they figured out that mold was causing their respiratory issues.
They both experienced asthma attacks and constant sinus problems. The doctor could find nothing really wrong with either of them.
After seeing an article online about the effects of mold on a person's health, my friend had a professional come and check her house for it. Sure enough, it was all in the walls.
My friend was renting, so she informed the landlord. He didn't want to put up the money to fix it, so she moved out. After a short while, she and her daughter started feeling so much better.