Property owners must abide by state and local building code regulations when undertaking property improvements, or work... moreProperty owners must abide by state and local building code regulations when undertaking property improvements, or work could be considered illegal. Consulting real estate lawyer Spain helps clarify what sellers must disclose about any illegal modifications that arise and potential liabilities of these changes to you as an owner or if the modifications impede on how you use the property, an attorney could provide guidance as to suing for damages or even withdrawing from a purchase contract if necessary.