Flat Seam
From Roofing, Solar Power, and Spray Foam Insulation Wiki
Flat Seam
(1) Two metal panels joined in a shingle fashion. The two panels can either be overlapped and fastened or folded and interlocked. Flat seam systems are made out of metal, which makes the roof durable, 100% recyclable and very low maintenance.
(2) A seam at the junction of sheet metal roof components that has been bent at the plane of the roof.