I was ready to ask some metal valley detailing Q's when I was hit by a curve ball yesterday: Metric vs. English/standard (12 x 36) shingles.
I haven't needed a roof in 25+ yrs. However the covered walkway between house & garage, particularly where it intersects the 5/12 roof on the house wasn't detailed, nor flashed properly. I found soft decking around the intersection area and a couple of holes.
So I tore it all off to have a look, and have done a lot of detailed carpentry work to fix rotted trim pieces in addition to replace the 1/2" ply deck. Went back with P&S in the three 5' valleys, 5" width strips to cover the ply edge at the eave and metal 2x2 drip w/ kick around the eaves. I'm also installing metal V-channel in the valleys.
So far, so good.
About the time I'm ready to put new shingles on, I discover the new ones I bought (only 2 sqrs for this area) are not 12x36, but 13-1/4 x 39-3/8! Furthermore, the roofing supplier I obtained these from no longer carries any 12x36 shingles...period! So I called another..no joy.
I'd planned on nesting new shingles over the old. Obviously that's not going to work here. I don't want to bridge them either. It was suggested I lay 30# over the old and shingle over them. Or tear them off. Or return what I have and scout for 12x36's.
Evidently the roofing world changed while I was busy doing other things! Metric shingles?? My layout guides/books are now (long) obsolete! Obviously this isn't news to you pros. And many, if not most, wouldn't even bother with a shingle-over, lay-over, or whatever you want to call it. Particularly when you have to warranty it.
I found a shingle I like, in the color I like and having to trim every one doesn't appeal to me. Neither does tearing off the old roof, in the Tx Summer.
So for those that do layovers, what other options are there for using a larger metric shingle over a smaller english one?