How to Install a Metal Roof at the Seams

Determine which type of seam you are dealing with. A flat seam between two panels is the most common type on metal roofs, and the easiest to deal with, while ridges and valleys require a little more work.

Place a strip of butyl tape along the edge of the first panel if you're installing two side-by-side panels, and place the edgemost rib of the second panel over it, sealing the seam. Drive screws through the overlapping ribs every 2 feet along their length to secure them in place.

Overlap the upper panel onto the lower by 6 inches if you're installing two panels in the same vertical section, and screw through them on either side of each rib.

Screw a strip of preformed valley trim to the point where the two roof angles meet, if that's the type of seam you're working with, before installing the flat panels that adjoin it. Place a strip of expanding closure foam along both edges between the trim and the flat panels to seal the seam.

Place a strip of expanding closure foam along the upper edge of the panels on both sides of the ridge, if a ridgeline is in fact the seam you're dealing with. Place the ridge trim over the gap and drive screws every 18 inches along the ridge's length on both sides.