How to Install Metal Roofing Valleys

J. Cavan Barry

Metal roofing is generally simple to install, but it can grow complicated on complex roof systems with several different faces.

While a large number of structures are designed in a simple, single rectangular shape, it is not unusual for a structure to be composed of two or more additions that result in several roof faces meeting and the need for installing metal roofing in their valleys. The metal used for roofing valleys is more comparable to roof flashing than roofing material.

  1. Lay a metal valley flashing panel in the roof valley at the bottom eave and drive one screw into each bottom corner about one inch from the edges (of the panel).

  2. Lay the next flashing panel towards the roof ridge, overlapping the first panel about four inches and drive one screw into each bottom corner as done in step 1.

  3. Drive screws (evenly spaced) along both side edges of the first flashing panel. Screw spacing may differ depending on panel size; 16 inches on center is a common spacing that can be used for most panel sizes. You can use a tape measure to reference screw spacing.

  4. Repeat steps 1 through 3 on remaining valley flashing panels, working your way to the roof ridge.

  5. Trim the final valley flashing panel to fit (when necessary) using the tin snips.