An asphalt roof shingles roofing need to be replaced every twenty years. Consider updating to a steel roof covering that lasts 40 to 70 years. Adding plumbing, electric, and staircases enhance the overall costs. The average cost to complete an attic room is $25,000 to $75,000 to convert it into living area. Renovating an already-finished attic room prices $10,000 to $30,000.