I would consult with an attorney in your area on the matter as many issues here will be specific to the law in Wet Virginia.  First, in many states (such as Texas) it is the buyer's obligation to confirm square footage.  Second, issues as to the home do not generally "survive closing" meaning that once the deal is done it is done unless there is title insurance etc., paid at closing. Finally, how you measure the house and how a professional measures it are two different things.  And if your house did indeed appraise for the selling price then that is significant here.  Good luck.