"I walked away from the deal based on non disclosure of a structural defect or damage, the dealer is not returning my deposit."
....this is Canada. No one can simply "keep" a deposit if a buyer decides to back out of a purchase
for any reason whatsoever. If you, for example, went to buy a new or used car, an aircraft, boat, refrigerator, insurance, ANYTHING, and gave a deposit for later delivery in this country (Provincial laws vary, but they are essentially the same cross-country in principle/intent), and you decide to back out of the deal FOR ANY REASON, you deposit MUST be given back IMMEDIATELY. Even signing a contract, you have a cooling off period where you can back out of the deal NO MATTER WHAT THE REASON. No lawyer needed.
Forensics on "the roof depression":
Sabconsulting nailed it: this depression likely existed for many seasons (or, years) based on his evaluation of the concentric evaporation stains.
