A professional seller (a real estate broker or a self-builder, for example) must take reasonable precautions to ensure that the property he sells is free of latent defects. It is important to note that upon discovery of a latent defect by the buyer, the professional seller is legally presumed to have been aware of it at the time of the sale.
A latent defect lawyer will advise you on the procedure to follow once you have reported the defect to the seller.