Hope I do not get in trouble asking this question here, I just do not know where to ask and trust. I have a cabin with a very nice looking, plain metal finish roof. Looking at buying a pole barn garage package to install alongside. Pole Barn folks tell me unpainted metal roof will rust out in 10 years. What is on my house? Are there plain metal finishes with 30-40 year warranties? Or is my roof painted, and I just do not know it?