My roommate has renters insurance - I do not. Her insurance only covers her own personal property and damages made by her.
We rent a top and 5th floor apartment in a building that has a roof deck. A coworker (highly-educated professional..so he wasn't some kid) stayed at our place for the night because he didn't want to pay for an expensive cab ride home. He has stayed before and he was a great guest. For some reason (he doesn't remember), that night, he was on our roof deck and decided to jump over the railing and fell 80ft and through the roof of the ground floor apartment (which happened to be a company leasing the space). Luckily, he walked out with only minor cuts! No illegal substances were involved at all.
Our coworker said he will be responsible for all the damages and repairs. However, we met w/ a manager of the ground floor company, and costs could be up to the hundreds of thousands of pounds - money our coworker does not have - and neither do we!
What can we do in this case?! The landlord has put all the safety precautions on the roof deck and it's not really his fault if someone decides to jump over the railings!
