This illustration was adapted from Chapter 4 of The NRCA Roofing Manual: Steep-slope Roof Systems—2013. The bubble at lower right shows the detail in NRCA ASPH-12A, which uses a one-piece counterflashing. The bubble at upper right and the main drawing show the detail in NRCA ASPH-12, which uses a two-piece counterflashing.
Tim Healey This illustration was adapted from Chapter 4 of The NRCA Roofing Manual: Steep-slope Roof Systems—2013. The bubble at lower right shows the detail in NRCA ASPH-12A, which uses a one-piece counterflashing. The bubble at upper right and the main drawing show the detail in NRCA ASPH-12, which uses a two-piece counterflashing.

Chris Hoppe, P.E. (online, 2/21/15): Fastening step flashing on the vertical leg is not recommended by many asphalt-roofing manufacturers or the National Roofing Contractors Association (NRCA). See — detail ASPH-12A. Fastening the vertical leg of the step flashing prevents one from removing it without removing the siding. Leaving the step flashing in place when reroofing does not allow one to inspect the underlayment at the roof-to-wall junction. It is my experience that most roof leaks occur at improperly installed penetrations and flashings.

Editor's note:The illustration at left is adapted from Chapter 4 of The bubble at lower right shows the detail in NRCA ASPH-12A, which uses a one-piece counterflashing. The bubble at upper right and the main drawing show the detail in NRCA ASPH-12, which uses a two-piece counterflashing.

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