How to Apply an Ice and Water Barrier to Roof Felt

Remove all roofing material down to the roof deck. This includes removal of roof felt. Ensure the plywood or other wood forming the roof deck is clean, smooth and dry.

Unroll the ice and water guard, and cut it into 10- to 20-foot long pieces, depending on the length of the roof edge and the size you can manage.

Roll each section back up, and set aside all but one roll. Remove the first 2 feet of backing paper from the first roll. The backing paper covers an adhesive.

Press the adhesive side into place on the roof, overlapping the eave or bottom edge by 1/4 inch.

Secure the adhered section of the roll with one hand, and remove more backing paper with your other hand slowly, pressing each newly unrolled section into place along the roof edge. Continue until the entire piece is secured to the roof.

Install the remaining rolls of ice and water guard until all roof edges or eaves are covered. Overlap the ends of each new roll by 6 inches to ensure an air- and water-tight bond between the two pieces.

Place the ice and water guard so that it extends from the eaves up to a point that is at least 24 inches inside the exterior wall. This ensures that it covers more than the maximum ice dam line. If you need to run a second course of ice and water guard to cover that amount of space, then overlap the second row 3 inches onto the first row.

Cut the ice and water guard lengthwise to install it along roof valleys and protrusions such as chimneys and vents. Cut enough to extend the guard at least 18 inches on each side of each valley and protrusion.

Peel away the ice and water guard's backing paper, and press the guard into place on a valley beginning at the valley's lowest point and moving upward. Work from the center of the valley outward in both directions. Repeat the procedure to protect each valley.

Install roofing felt on the uncovered portions of the roof deck after the ice and water guard is installed. Begin at the lowest point, lay the felt as flat as possible and overlap the felt at least 2 inches over the edge of the ice and water guard.