How to Install Gutter Flashing

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Things You'll Need

  • Tape measure

  • Ladder

  • Roofing nails

  • Hammer

  • Pencil

  • Tin snips

Gutter flashing is also commonly known as a gutter apron. It is installed on the top of the roof near the eave of the house and is slid under the shingles. The gutter flashing comes in various widths and 12-foot lengths. It is a solid sheet that is pre-formed to fit under the shingles and over the gutter underneath the roof line. It helps direct rain water into the gutter and prevents water damage to the fascia and soffit. Installing gutter flashing is one of the final steps of the installation process for gutters.


Step 1

Measure all the sides of the roof line of the house with a tape measure, and record the measurements. Add all four sides together for the total number of feet. Divide that number by 12 to get the number of pieces of flashing necessary for installation. Add an extra piece to your total to compensate for odd lengths of cuts that will be made.


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Step 2

Position a ladder on the ground at any corner of the house. Climb up the ladder, and pull back the shingles at the corner of the roof by hand. Move down the entire distance of the first side, and pull back all the shingles. Reposition the ladder when necessary.

Step 3

Slide the ribbed end of the gutter flashing underneath the shingles, and insert a 1-inch roofing nail every 16 inches down the center of the gutter flashing with a hammer. Nail the bent side of the flashing over the gutter at the same 16-inch locations down the entire piece.


Step 4

Overlap the second piece by four inches, and nail it down at the overlap. Install the second piece and all the remaining pieces of the first side in the same manner until reaching the end of the wall. Measure and mark the cut line of the final piece with a tape measure and pencil if a cut must be made for it to fit. The measurement for the final piece should include a 4-inch overlap from the edge of the last length of flashing.


Step 5

Cut the final piece to size with tin snips. Follow along the pencil mark. Install the final piece of the first side in the same manner. Nail the shingles back down into place with roofing nails. Move on to the next side, and repeat the process for all of the sides of the house.


Be very careful when working on a ladder. Make sure it is on level, steady ground when you are on it.

Wear gloves when using tin snips to prevent cuts by the snipped metal.