What is the test for determining whether a latent defect in a building can be found to be a "latent defect" in a construction contract?

I am satisfied that the reasoning in Mautner v. Metcalfe, [2008] O.J. No. 424 coincidentally decided by me, applies to this case. Therein I quoted Laforme J. in Swayze v. Robertson [2001] O.J. No. 968 where he stated: A “latent defect” as it relates to the case at bar is in effect some fault in the structure that is not readily apparent to an ordinary purchaser during a routine inspection. And ordinarily, if a vendor actively conceals a latent defect, the rule of caveat emptor no longer applies and the purchaser is entitled, at their option, to ask for a rescission of the contract or compensation for damages.

This must also be considered in the context of the purchaser hiring an inspector. Again citing Swayze v. Robertson I accepted the following principles: 6. In summary, these are the extracted principles I intend to apply: (a) the vendor is not bound to call attention to patent defects; the rule is “caveat emptor”; (b) where there is active concealment of an otherwise patent defect, the general rule of caveat emptor will not apply; (c) if the vendor actively conceals a latent defect, the rule of caveat emptor no longer applies and the purchaser is entitled, at their option, to ask for a rescission of the contract or compensation for damages; (d) a vendor may be liable to a purchaser with respect to premises which are not new if he knows of a latent defect which renders the premises unfit for habitation. But, as is pointed out in the lecture above referred to, in such a case it is incumbent upon the purchaser to establish that the latent defect was known to the vendor, or that the circumstances were such that it could be said that the vendor was guilty of concealment or a reckless disregard of the truth or falsity of any representations made by him; and (e) where there are no “clues” and no reasonable means of testing for defects that liability for actively concealing defects, whether patent or latent, actively not disclosing latent defects, or fraudulently misrepresenting facts relating to latent defects, remains with the seller, subject to the requirement with respect to active concealment or active non-disclosure that the same constitute a fraud on the purchaser the same as a fraudulent misrepresentation would.