Homeowners are required to obtain permits for all work structural improvements that are performed on their property. In the event a structural improvement was performed prior to when you purchased, it would be the responsibility of the prior owner to produce documentation evidencing that the proper permits were obtained and that the improvement was signed off by the Department of Buildings. This article explains the process further. If you happen to be a seller faced with the fact that an improvement does not have the proper sign off , you will be required to remedy this , even though you bought the property this way. Some lenders will require that an escrow be held pending that delivery of the sign off to the lender. Read more