You are right that there are a lot of variables in the contractor, metal type, and coatings. Typical housing roof metal is rated at 50 years, a big longevity factor is in the installation and fasteners used, going cheap will make leak holes. I was told to hire a company that specializes in only metal for the install.ksalvagno said:
I researched for about a year and never came across the re-coating problem mentioned as it would certainly make a big difference in choices, bare tin was the defacto and never needed re-coating in 100 years, they may of needed to retouch the nails with tar but seldom anything beyond that. Stainless fasteners on a expanding clipped standing seam is the best way to go.
My new place will have metal as I doubt I will live long enough to need re-coating even if I do cut down on my carbs. I mostly want it because of solar panels and rain harvesting and don't want to have to yank it all off in 15 years to put new shingle under it. I also liked the 120mph wind rating as compared to the 65mph rating of the shingles I just put on.
20 years ago I lived in a 1870 hotel and had to get an artisan up on the roof for some special tuck pointing and copper flashing work that nobody younger than 70 would touch. The old guy said it was the original metal roof from 130 years ago. He did some of the best work I have even seen and could not read or write in any language.
