The cost to build an unfinished garage varies by project, depending on what tasks the homeowners can capably complete on their own or are willing to live without. Usually, painting is left off of the contractor’s project. Painting costs $1.50 per square foot on average, and installing cabinets as a DIY project will reduce labor costs by a few hundred dollars. An unfinished garage typically costs only a small percent less than a finished garage, but the rates vary by region.