Measure the backsplash area with a tape measure to determine the amount of flashing needed. Put on a pair of work gloves and safety goggles and then measure out the amount of flashing necessary to cover the backsplash area from the roll of flashing. Measure both the wall and the roll twice, to ensure that you have the right amount.
Mark the cutting line with a pencil and then cut the flashing using a pair of tin snips and a straightedge to guide the cut at the marked location. Cut the flashing to match the length of the wall to create a single backsplash panel spanning the entire backsplash area.
File down the edges of the flashing to round off the sharpness of the material. Apply the file from the face of the edging to the rear that will sit against the wall until the edge is smooth to the touch. Wipe away any metal filings with a piece of cloth.
Wash the walls with a mild liquid detergent and warm water mix using a scrub brush to remove dirt and grease from the surface. Allow the walls to dry before applying the flashing.
Use a screwdriver to remove any wall outlet covers from the outlets located within the backsplash area. Test fit the backsplash against the wall to make certain that you cut it to the proper length. Mark the location of any wall outlets onto the backsplash with a pencil for cutting through the material to allow outlet access.
Remove the backsplash from the wall and then cut the outlet locations from the material using a utility knife. Test fit again to make certain that the cuts were properly placed. Mark any mistakes, remove the flashing and then make any necessary adjustments.
Cover the rear of the flashing with an adhesive caulking compatible for adhering metals to surfaces. Use a zigzag pattern along the center of the flashing and straight lines about an inch from the edges. Place the backsplash against the wall and then press it into place, working your way down the wall and adjusting the position of the flashing to ensure it meets the outlet openings.
Allow the flashing to dry in place for 48 hours and then replace the outlet covers to complete the backsplash placement.