How to Flash a Deck Ledger

Flashing, otherwise known as drip edge, is typically constructed of galvanized steel and is available in a wide array of colors to match any project. For ease of installation, you can buy the flashing already bent to contour to your project dimensions. When working with ledger board, use flashing featuring a 3-inch upper lip and a 1 1/2-inch center bend to protect the deck ledger from moisture and other outdoor elements.

Installed ledger board
Installed siding
Tape measure
Contoured galvanized steel flashing
Marker
Tin snips
Clear silicone
Galvanized fasteners (optional)
Medium-duty work gloves

Instructions

- 1
  Measure the length of the ledger board to determine how much flashing you'll need. Add at least six inches to the length to account for an overlap at the flashing ends.
- 2
  Lay the flashing out next to the ledger board to preview how it will look once it's installed. Overlap the flashing's butted ends by at least six inches to provide protective coverage at the flashing breaks. Trim long lengths of flashing down to fit smaller areas by measuring the ledger board, transferring the measurement to the flashing, and cutting along the indicated line using tin snips.
- 3
  Inspect the siding material for any fasteners that secure the lower edge to the building. Remove any fasteners that would prevent the flashing from sliding underneath using the correct tool. Remove screws with a screw gun and nails with a hammer featuring a nail remover.
- 4
  Slip the flashing's top edge two to three inches under the siding material, working from one end of the ledger board to the other. Apply a generous amount of clear silicone between the flashing at the point where it overlaps.
- 5
  Manipulate the flashing so that each bend in the galvanized steel sits flush against the structure sheathing and the top of the ledger board. Ensure that the drip edge hangs off the side of the ledger board.

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