Building and subtrade permits are done on the HillsGovHub online system. Obtain an Engineering Affidavit.The review of the site design for compliance with technical requirements of Hillsborough County. B. Cross Reference to Land Development Code. Proper documentation to Project Manager for time extension consideration. 15. Closeout. The proposal shall be submitted within the time limit indicated in the request for any extension of such time limit as may be s ubsequently granted.