Smoking and lying about it.

[Jo Jones]

Hello, 

I recently found out both my tenants smoke and they lied about it. I had them sign a Lease and in that lease they agreed to the no smoking rule. 

So, I am choosing to pick my battle here but they now want to move into our front duplex that we are remodeling to all brand new. I, of course will have the same rule but knowing they smoke, I am reluctant to have them rent it. 

My question is this: if something awful were to happen, like a fire, what, who, when would happen?

Would they be responsible for the damages? Thanks