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The life expectancy of a metal roof is typically, 20-60 years, depending on manufacturer and materials.

“The research study concluded that the expected service life of an unpainted 55% Al-Zn coated steel standing seam roof constructed today in a wide range of environments using best practices can be expected to be in excess of 60 years” (1)

” low slope metal roof manufacturers offer 20- to 40-year warranties on their products.” (2)

” all roof systems require a regular maintenance program (at least annually) to clean off debris and to inspect the condition of the roof in order to achieve the kind of service lives shown in this study. While low-slope steel standing seam roof systems were projected to last up to 60 years, ancillary components (such as fasteners) may need to be replaced during the roof life, but this represents significantly less than 20% of a total roof replacement cost.” (1)

(1) http://www.metalconstruction.org/index.php/media-center/press-releases/metal-roofs-can-last-60-years

(2) http://www.metalconstruction.org/index.php/applications/low-slope-roofs