i am planning to put a metal roof on my house. i like the look of the non painted galvalume. i have checked at several places and they have a 20-25-30 year warranty. is it not all the same if it is galvalume? the 30 yr was several states away. if you know please Help. thanks
I am an architectual sheet metal worker and do metal roofs all of the time. Although they are all galvalume they may be different processes or slightly different compounds as manufactures tend to very slightly. Also you want to look at the gauge of the metal. Just like with wiring the lower the number the thicker the metal
As mentioned above, the warranty difference is likely difference in gauge (thickness) or possibly fastener type. A hidden fastener system is likely to be leak free longer than an exposed fastener system. Make sure you're comparing apples to apples.
Also, some manufacturers are more realistic with their warranties. A 30 yr warranty full of loopholes may be worth less than another manufacturer's 20 yr warranty.