New York City Department of Buildings 8-hour Suspended Scaffold User Refresher Class in Brooklyn, NY. NYC Requirement: To use or work on a Suspended Scaffold, complete 16 hours of user training and then 8 hours of refresher every 4 years. NYST is a DOB Approved Training Provider (4B47). This course meets DOB requirements. For workers with 16-hour card needing refresh. Class added to Worker Wallet profile upon completion.