In flat seam construction, which statement is correct?

• A. An edge formed in a rollformer.
• B. Like a standing seam that has been bent flat.
• C. The same as a snap lock.
• D. Only used on round pipe.

Answer: (B)

Flat seam construction is basically a standing seam that has been bent down flat to lie flush with the panel surface. Start with a standing seam, where the edge is folded up to create a vertical seam, and then bend that seam over so it sits level with the panel. This yields a low-profile, flush joint across sheets, which is why the description of a standing seam that’s been bent flat is the best way to describe flat seam. It’s not simply an edge formed in a rollformer, nor is it the same mechanism as a snap lock, and it isn’t limited to round pipe.