We are considering purchasing a home that is built into a hillside and has a sod roof. We live in southwest Michigan. It is my understanding that a sod roof lasts about 20 years. The home is 21 years old. Does anyone know about maintaining a sod roof, how to replace a sod roof, or if a sod roof can be easily replaced with metal roof, or other type of roof, and what is involved in taking a sod roof off? I've tried a search for sod roofs on Google, and it's overwhelming! Any information would be greatly appreciated!

Thank you!