Quote Originally Posted by Irving View Post
Metal has a lot of areas to leak, especially if it's a pretty cut up roof. Just like a tile roof, the metal will last a lot longer than the fasteners or any underlayment so while the roof might be in tact years from now, it may leak like a sieve.

I don't want to sound too negative though, as there are down sides to every type of roof design and roof material.
I built my soon to be X garage pole building. 56" snow load and 120mph wind. 2x4 purlins on end is the only sub structure for the roof. Replaced the entire roof system on the house. Everything but the trusses came off. 3/4" osb and tar paper underlayment. 10yrs and 8yrs respectively and no leaks. Lots of stitcher screws on the seams and foam spacers on the ends. Both have seen 3'-4' of snow melt on them. Not backwash under the seams.

I have an acquaintance that has an early '70s built PB and a metal roof, on there house, from the same era. Again no leaking.

I'm not talking about the pinch fit metal roofs that are popular these days. These are screwed together and are weather tight.