Flat maintenance cost

Ask tenant for vacation of the flat under these following circumstances. 

If there is loss of property’s value or its utility owing to the tenants action. ..
 

If the neighborhood finds any action of your tenant objectionable situations in the flat ..
 

If the second floor owner is not residng/occupying the house and  is not paying the routine maintenance amount too, then you can request him to share the maintenance amount to some barest minimum extent in order to tide over the maintenance charges that is required to maintain his house property too within the complex.

You can send a written communication in this regard and secure the copy as an evidence to p[rove the steps taken by you in this regard.

You can send the communication by registered poost with an acknowledgment card.

In the meantime you can obtain a report from a qualified structural engineer assessing the damages due to where and tear  or depreciations etc., the estimated cost and immediate necessity/attention to renovate the building  and discuss with the second floor neighbor, if he is not ready to participate in the discussion to arrive at a solution, you may send a legal notice to him in this regard highlighting the apprehended dangers due to his reluctance/ non cooperation and warn him that he will be dragged to court of law for remedy if he still continues to maintain the hostility in this regard. or wouild be liable to pay his share of amount towards the renovation charges/expenses.