I am assuming that you are either using a standard form of residential lease with the blanks filled in, and no other changes, or that you have an oral lease. In either event, while the landlord is commonly responsible for repairs to and replacement of the structural portion of the property, the roof, the appliances, etc., an exception exists where the tenant either intentionally or negligently damages a part of the property. In such cases, the tenant is responsible for the repair/replacement.