Finishing a basement is a popular choice for many homeowners, turning an underused area into a valuable living space. The cost to finish a basement in Islip, NY, can vary, especially based on the size – such as a 1000 sq ft area – and the level of finish desired. Basic finishing includes framing, drywall, and standard electrical work, while more comprehensive projects might include installing a full bathroom, a kitchenette, or custom-built features.