Legal Question in Real Estate Law in Maryland

It would be difficult to establish that the realtor was aware of the issue and failed to disclose it. The realtor, by the terms of the listing agreement (assuming this is the listing agent), assumes no responsibility for the seller's nondisclosure of such information. The same is true of the selling (buyer's) agent, who isn't even a party to the listing agreement. You might have a claim against the seller, although I suspect you realize the difficulty of pursuing it at this juncture. It seems strange that the seller was able to get a building permit if the plans weren't in compliance with code.