I had a roofer redo a home for me and the insurance estimate said it needed 3 layers removed and replaced. The contract with the roofer said he would do 3 layers. The job was partially completed and an inspector checked the roof and said our contractor had only install 2 layers. I called the city code department and they said if you remove 3 "roof systems" you can only put back 2 "roof systems" so it is possible our contractor is doing it correctly. I don't know anything about roofing so getting 2 instead of 3 of something doesn't sound good. I don't know what a "system" is versus a layer anyway. The roof is now sealed up and done. Any advice on this is appreciated. We don't want to find we have a 6 year life roof instead of 15 for the same cost.