Nonconforming Duplex

I have a question about a seller’s obligation to disclose that a property is nonconforming. If the City will not allow a property to be rebuilt if it burns down, does seller’s Realtor have an obligation to disclose this information before an appraisal and mortgage is done?

Question: What is the legal obligation and consequences for a seller’s Realtor or Seller for not disclosing that a property is nonconforming?

I would think that would be a material fact that could affect the value of the property.

However, as long as the property is standing you are permitted to continue using the property as it is in use now. If your property burns down you can take the insurance money, sell the lot, and purchase something else instead.