Drywall repair costs can vary depending on the size and complexity of the job plus the materials required. A small 2" square ding might cost $100, while repairing an entire 20x20 ceiling might cost over $1000, and replacing all the drywall in a water-damaged room might cost over $3000 after drywall finishing, texture and paint. It's important to replace water-damaged drywall as soon as possible, because mold can grow invisibly behind wet drywall, and can soon affect your indoor air quality and your family's health.