What is the test for patent ambiguity in the meaning of the term "steel warehouse"?

In Hamilton Region Conservation Authority v. Eaton [1974] O.J. NO. 644, the court admitted evidence of the intention of the parties as to the meaning of the term “steel warehouse”. The evidence before the court seem to be that there were at least three structures on the property which could be described as a steel warehouse. Although the court described this as a patent ambiguity, I regard this case as coming within the latent ambiguity exception to the principal of objective interpretation of a contract. The phrase “steel warehouse” is not on its face patently ambiguous or susceptible of more than one interpretation and the ambiguity only became apparent from a consideration of the surrounding circumstances or the factual matrix which established that there were at least three structures which could be described as a “steel warehouse”.