Place the drip edge under the first row of shingles along the bottom of the roof, and secure the drip edge with roofing cement. Further secure the drip edge with roofing nails at each end if necessary.
Position the drip edge so that it extends past the fascia board by 3/4 inch. Apply roofing cement where the drip edge meets the shingles, and press down lightly on the shingles. When nailing the ends of the drip edge, drive 1 1/2-inch nails as far back under the shingle as possible to prevent leaks.
Another option to secure the drip edge is to nail the drip edge into place using nails that match the material of the drip edge. For instance, use galvanized steel nails when installing a galvanized steel drip edge. In high rainfall areas, set the nails 6 inches apart. In drier areas, place the nails up to 12 inches apart or at each rafter along the edge of the roof. The nails should penetrate the roof decking.
When installing a drip edge on a new roof, bend the drip edge to match the pitch of the roof before installing it. If the fascia board is rotted or has water damage, remove and replace it before installing the drip edge.