David,
I think we are talking about the same thing. The standing seam (as you describe normally have a seal along the vertical edges along with the hidden screws. The others, which down here you can buy the panels at any HD, Lowes or other home improvement store normally do not have a seal along the vertical edge.
The instructions I’ve seen for both tell the home owner to have a weather barrier underneath, felt or otherwise. Many (most) roofers who install retrofits down here simply install these over their existing roofs and use that. Saves on tear off costs, and is usually as good as a new felt layer would be or better. Also keeps them from seeing the rotting sheathing, so they don’t have to do anything about it :shock::mrgreen:
All the manufactures I’ve talked to say that these roofs just like comp shingled roofs are expected to allow a minimal amount of water into them and that water needs to be able to drain out somewhere. I’ve never seen any sealant where a higher panel sits over the top of a lower panel (horizontal seam) as that would stop water that had gotten in under the roof from draining out.
I was just checking to see if they were doing something differently up there.
I Frequently see these on barns and other buildings in ranchettes as well. On barns they frequently are over skip sheathing, usually every 3-4’. Make a he11 of a noise during a storm and the little woman is always amazed that their horses don’t stay in the barns when it storms :shock::shock::shock: What rich people skimp on is always amazing.:mrgreen::mrgreen:
– bz