Tenant responsible for damage due to negligence

[Chad C.]

I have a tenant that has had some water damage due to a leaky roof, and at this point the damage is quite extensive. The tenant has been in there for eight months, and I have owned the unit for six months. They said that the drywall was saturated and crumbling in an 8x12 area, and the repair man said the leak has been going on for a while, possibly before they even moved in, but I didn't notice it when I bought it. I'm going to replace the roof, which is my responsibility. But the question is the extensive damage that's done to the inside, that 8 x 12 area needs new drywall, studs, and rafter sill plate. The lease states that they are responsible for this, but strategy wise, I think I would just push the tenants away. They would leave, I would never be able to get the money, and I would be without rent for a few months. These are very low income tenants. I should be able to keep their security deposits. Do y'all have any examples where y'all made tenants pay for damages, and it was for the best, or worst?