Texas Property Code - PROP § 92.054. Casualty Loss

(a) If a condition results from an insured casualty loss, such as fire, smoke, hail, explosion, or a similar cause, the period for repair does not begin until the landlord receives the insurance proceeds.

(b) If after a casualty loss the rental premises are as a practical matter totally unusable for residential purposes and if the casualty loss is not caused by the negligence or fault of the tenant, a member of the tenant's family, or a guest or invitee of the tenant, either the landlord or the tenant may terminate the lease by giving written notice to the other any time before repairs are completed.  If the lease is terminated, the tenant is entitled only to a pro rata refund of rent from the date the tenant moves out and to a refund of any security deposit otherwise required by law.

(c) If after a casualty loss the rental premises are partially unusable for residential purposes and if the casualty loss is not caused by the negligence or fault of the tenant, a member of the tenant's family, or a guest or invitee of the tenant, the tenant is entitled to reduction in the rent in an amount proportionate to the extent the premises are unusable because of the casualty, but only on judgment of a county or district court.  A landlord and tenant may agree otherwise in a written lease.