Navigating the NYC Department of Buildings is a major hurdle for any homeowner. This guide demystifies the entire permit process for your renovation. Learn when you need a permit, the crucial difference between an ALT1 and ALT2 filing, and the step-by-step process for getting your plans approved. We cover realistic 2025 costs, project timelines, and the unique challenges of co-op board approvals. With 10 interactive tools, this guide will help you plan your renovation with confidence and avoid costly stop-work orders.