Turns out steel roofing does not last forever, though it almost sounds like steel roofing manufacturers make that claim.
The longest life roofing may be some kind of tile. According to Eagle Roofing, modern metal roofs have a projected lifetime of 45 years. Of course, that is a projection, galvealume and modern PVDF coatings haven't been around that long. Top quality roofing manufacturer Berridge only guarantees the finish and the roofing panels for 20 years. Meanwhile, Eagle claim tile roofs have a 75 year lifetime, and their tiles are guaranteed for a "lifetime" (lifetime of what or whom?). Tile roofs have on historic buildings have been around for centuries (however not without maintenance).
Concrete tile roofing is available in highly reflective colors, all the way up to a white with SRI of 96, exceeding the reflectivity of PVDF white coated steel. (Eagle makes that color, Hanson tiles only do a light colors with SRI up to 45.)
Two shortcomings of tile: (1) it rarely has the highest impact resistance. Hanson tile is only rated to class III. Most Eagle tile is rated to class III also, the exceptions are the flat tile which is rated to Class IV. (2) Freeze/thaw cycles, though concrete tile manufacturers claim their product is fully resistant.
But the different lifecycles themselves of different roofs need to be considered. Tile, especially of the non-flat variety, randomly breaks from hail and other weather events. Thus it needs to be inspected periodically, perhaps annually. The cost is not in replacing the tile, which is either cheap or lifetime warrantied. The cost is in the work of replacing tiles. Metal roofing does not require annual breakage inspection. What happens first is that the coating deteriorates. Thus, repainting is required in about 20 years. Since externally applied paint probably won't be as good as factory coating, future repainting could be 5-10 years. If you're not fussy about appearance, it could go longer. But failure to recoat could lead to premature failure (though that seems doubtful for galvalume, one would think it would be OK without coating).
Thus the maintenance story goes like this: tile roofs require frequent, but relatively inexpensive maintenance, to maintain water shedding performance. Metal roofs require infrequent, but comparatively expensive maintenance, largely to maintain appearance and long term lifespan. Then, the metal roof will need to be replaced entirely sooner.
A third type of material shows up as well as metal in Eagle's roofing lifetime charts. Polymer shingles. I need to check those out.
The longest life roofing may be some kind of tile. According to Eagle Roofing, modern metal roofs have a projected lifetime of 45 years. Of course, that is a projection, galvealume and modern PVDF coatings haven't been around that long. Top quality roofing manufacturer Berridge only guarantees the finish and the roofing panels for 20 years. Meanwhile, Eagle claim tile roofs have a 75 year lifetime, and their tiles are guaranteed for a "lifetime" (lifetime of what or whom?). Tile roofs have on historic buildings have been around for centuries (however not without maintenance).
Concrete tile roofing is available in highly reflective colors, all the way up to a white with SRI of 96, exceeding the reflectivity of PVDF white coated steel. (Eagle makes that color, Hanson tiles only do a light colors with SRI up to 45.)
Two shortcomings of tile: (1) it rarely has the highest impact resistance. Hanson tile is only rated to class III. Most Eagle tile is rated to class III also, the exceptions are the flat tile which is rated to Class IV. (2) Freeze/thaw cycles, though concrete tile manufacturers claim their product is fully resistant.
But the different lifecycles themselves of different roofs need to be considered. Tile, especially of the non-flat variety, randomly breaks from hail and other weather events. Thus it needs to be inspected periodically, perhaps annually. The cost is not in replacing the tile, which is either cheap or lifetime warrantied. The cost is in the work of replacing tiles. Metal roofing does not require annual breakage inspection. What happens first is that the coating deteriorates. Thus, repainting is required in about 20 years. Since externally applied paint probably won't be as good as factory coating, future repainting could be 5-10 years. If you're not fussy about appearance, it could go longer. But failure to recoat could lead to premature failure (though that seems doubtful for galvalume, one would think it would be OK without coating).
Thus the maintenance story goes like this: tile roofs require frequent, but relatively inexpensive maintenance, to maintain water shedding performance. Metal roofs require infrequent, but comparatively expensive maintenance, largely to maintain appearance and long term lifespan. Then, the metal roof will need to be replaced entirely sooner.
A third type of material shows up as well as metal in Eagle's roofing lifetime charts. Polymer shingles. I need to check those out.
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