I don't know anything about plumbing. When I am starting shower on upper floor toilet then water start leaking on the garage ceiling. Where to start checking and how to start checking. Any help is very much appreciated.

I don't know anything about plumbing. When i am starting shower on upper floor toilet then water start leaking on the garage ceiling. Where to start checking and how to start checking. Any help is very much appreciated.
... in the plumbing section for a prompt and thorough answer.

Garage ceiling is leaking, how to fix it?

Please start a new thread. This one is 3 years old. Give more details, do you think this is a plumbing problem or a roof leak? If youthink plumbing post on plumbing site, roof post on exterior home improvement.