A just-released research study from MCA concluded that a new or retrofit low-slope Galvalume roof, in a wide range of environments, does not require replacement during the building’s ENTIRE service life! This is a significant advantage over non-metal roof systems that require one or more full replacements within a typical building's 60-year service life.
In the study, low-slope standing seam metal roof systems, using 55% Aluminum-Zinc alloy coated sheet steel (better known as Galvalume), experienced corrosion rates that conservatively project service lives ranging from 60 to 375 years (beyond the service life of most buildings!), depending on the local precipitation pH.
Even sheared edges and panel profile bends had an absence of significant red rust after up to 35 years, indicating exceptional corrosion resistance in areas susceptible to exhibiting the first signs of corrosion.
The research study concluded that the expected service life of a similar metal roof constructed today in a wide range of environments using best practices can be expected to be in excess of 60 years, a value that equals the assumed building service life as described in LEED, version 4.
As with all roof systems, a regular maintenance program (at least annually) should be in place to clean off debris, etc. in order to achieve the kind of service lives shown in this study. While these low-slope steel roof systems were found to last up to 60 years, ancillary components (such as fasteners) may need to be replaced during the roofs life, but this represents significantly less than 20% of a total roof replacement cost.