How to repair valley flashing on tile roof

Written by j. cavan barry | 13/05/2017
How to repair valley flashing on tile roof
Tile is a commonly used and effective roofing material used all over the world. (tile roof image by dbvirago from

Tile is a commonly used roofing material that has been used throughout history in all regions of the world, and is available in dozens of different styles. A roof valley occurs when two roof planes meet, and in the case of tile roofing, galvanised metal flashing is installed in these valleys to carry water off the roof, preventing damage. While the metal roof valley flashing is durable when installed properly, a number of different variables can negatively affect its integrity. Replacing damaged areas of roof valley flashing is vital to protect the roof structure from any damage from weather.

Remove the surrounding roof tiles. Most roof tiles will simply lift out, but some may be nailed to the roof. Carefully remove any nails using the flat pry bar.

Remove the roofing nails within 30 cm (12 inches) of the damaged flashing area, using the flat pry bar.

Cut the flashing horizontally 15 cm (6 inches) on both sides of the damaged area and pull the cut flashing from the roof surface.

Cut a new piece of roof valley flashing 20 cm (8 inches) longer than the piece removed in Step 3, using the metal cutting shears.

Slide the newly cut roof flashing under the upper portion of the roof valley flashing. The existing flashing should overlap the new piece by about 10 cm (4 inches). The lower portion of the new piece of flashing should rest over the lower existing flashing, overlapping about 10 cm (4 inches).

Using the roofing hammer, drive roofing nails about 2.5 cm (1 inch) from both lower edges of the new flashing so the nails penetrate through both pieces of new and existing flashing. Do the same at the upper edge of the flashing.

Drive roofing nails about 15 cm (6 inches) on centre and about 2.5 (1 inch) along the side edges of the new flashing.

Return the roof tiles that were removed in Step 1 to the roof. Carefully return any nails removed if necessary.

Things you need

  • Flat pry bar
  • Roofing hammer
  • Metal cutting shears
  • Metal valley flashing
  • 2.5 cm (1 inch) roofing nails

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