What is the test for determining whether a defendant is liable for property damage?

The law does not apportion damages between tortious and non‑tortious causes. The plaintiff is required to prove that the defendant's tortious conduct "caused or contributed to the plaintiff's injury. The causation test is not to be applied too rigidly. Causation need not be determined by scientific precision": Athey v. Leonati, 1996 CanLII 183 (SCC), [1996] 3 S.C.R. 458, at para. 16. The defendant need not establish that the defendant's conduct was the sole cause of the injury; it is only necessary that the defendant be "part of the cause of an injury, the defendant is liable, even though his act alone was not enough to create the injury. There is no basis for a reduction of liability because of the existence of other preconditions: defendants remain liable for all injuries caused or contributed to by their negligence": Athey at para. 17 (emphasis in original.) The analysis is often framed as a "but‑for" test. As Major J. noted in Athey, "the essential purpose of tort law … is to restore the plaintiff to the position he or she would have enjoyed but for the negligence of the defendant": Athey at para. 20. Property damage