Slowgsr - Please explain - "double strapping" layout -
"Alternatively a 2x4 double strapping system can be used which gives a full vented space from sofit to ridge under the metal panels, if roof venting is questionable. Also gives the chance to shim for dips and sags. "
Marc
we strip to plywood, remove all fascia, gutters, soffit.
High temp peel & stick the deck wrapping the fascia.
Strap the roof with 2x4 up each truss, screwed down every 12"
Then double strap the edge with 2x4s, down the fascia also, every 16" up after (single strap) double strap along ridge vent opening, sides of any valleys etc. We string line everything and shin between both layers of strapping. Its very very fine consuming but gives a straight flat roof for metal.
The strapping in opposite directions and down the fascia allows for an airspace up the fascia to the space between the deck and panels and up out the ridge. The sofits are cut for venting as well and gets a perforated continuous strip which vents the attic, and underside the roof.
The straight runs get seamed by hand with hand seamers twice, so 4 passes per seam. First does the single lock, second is double. The seamers have a plastic type guide to not scratch the metal.
Hand seaming entire panel lengths would be ludicrous, I suspect you've never done double lock jobs other then detail pieces, snap lock is not the same, your probably doing American style. (Do your best caulk the rest).
Hand seamed the double lock across the dormer ridge,
The fascia and sofit is also standing seam except 12" exposure and single lock.
The gutters are 6" half round and use deck mounted hangers that must be bent to slope.
My house is about 25 square (small) and there is 130ft of sofit, fascia, gutter, and a covered porch. There was 1 dormer, 1 chimney (also rebuilt) and interlocking metal siding was also done. (Hand made). There was basically no budget. Me and a friend did it. He's the pro, I learned a ton.
Some photos of the dormer all double locked, valley is an interesting setup as it uses a double hem. I wouldn't double lock a valley (no room for movement) but that's a different topic.
The 2nd photo shows the completed ridge cap also. There are no exposed fasteners on the roof and nothing relies on caulking.
I however need some snow guards, undecided to do what I've been doing, clearing substantial accumulation, or doing a rail at outside wall, maybe just over the deck, driveway and entrances.
