In what circumstances will an appraiser be found liable for failing to detect dry rot and insect infestation?

In Cantwell v. Petersen, supra, Cashman L.J.S.C. dealt with a claim against an appraiser for damages for negligence in failing to detect dry rot and insect infestation in the foundation of a dwelling house. The plaintiffs had applied for a mortgage to purchase the property, the mortgage company required an appraisal and the appraisal was supplied by the defendant. Cashman L.J.S.C. found the defendant liable saying at p. 299 [25 R.P.R.]: I find as a fact that in the circumstances of this case that while the plaintiffs may in all probability would have proceeded [sic] with the purchase of this property had they not seen the appraisal they were in fact fortified in their decision to buy the property because they did see the appraisal prepared by the defendant and were in effect persuaded to continue with the purchase. On the question of damages Cashman L.J.S.C. says at p. 302: Both counsel are in agreement that there are two methods of calculating damages in a case such as this: 1. Cost of correction; 2. The difference in value between what the plaintiffs received and what they bargained for. And at p. 307 the judge says: In the circumstances of this case I conclude that the proper method of assessing damages must be on the difference between what the plaintiffs bargained for and what they received.