For those residential dwelling properties affected by the floods and under contract, I refer you to section 64 of the Property Law Act and Christensen et al, Land Contracts in Queensland – Risk of subject matter (pp 184-192),
Georgeson v Palmose & Anor (1962) 106 CLR 578 and Cruse v Mount  Ch 73.
PLA 64: Right to rescind on destruction of or damage to dwelling house
(1) In any contract for the sale of a dwelling house where, before the date of completion or possession whichever earlier occurs, the dwelling house is so destroyed or damaged as to be unfit for occupation as a dwelling house, the purchaser may, at the purchaser’s option, rescind the contract by notice in writing given to the vendor or the vendor’s solicitor not later than the date of completion or possession whichever the earlier occurs.
(2) Upon rescission of a contract under this section, any money paid by the purchaser shall be refunded to the purchaser and any documents of title or transfer returned to the vendor who alone shall be entitled to the benefit of any insurance policy relating to such destruction or damage subject to the rights of any person entitled to the insurance policy because of an encumbrance over or in respect of the land.
(3) In this section–
sale of a dwelling house means the sale of improved land the improvements on which consist wholly or substantially of a dwelling house or the sale of a lot on a building units plan within the meaning of the Building Units and Group Titles Act 1980 or the sale of a lot included in a community titles scheme under the Body Corporate and Community Management Act 1997 if the lot–
(a) wholly or substantially, consists of a dwelling; and
(b) is, under the Land Title Act 1994—
(i) a lot on a building format plan of subdivision; or
(ii) a lot on a volumetric format plan of subdivision, and wholly contained within a building.
(4) This section applies only to contracts made after the commencement of this Act and shall have effect despite any stipulation to the contrary.
Brisbane Barrister – David Cormack