In MN you should expect to get 20 years of service out of an architectural shingle roof. Shingle manufacturers rate most architectural shingles to last for 30 years. However, this is the longest you should ever go before replacing an architectural shingle roof. It is not recommended to push an architectural shingle to its full lifespan because leaks may arise as it nears the end of its life. In MN, if you get 20 years out of an architectural shingle you are doing good.