Now that you've learned how to flash the roof edge with the help of our good friends and roofing contractors Tucson Roof Gurus, install base tie-ins in and inside corners, let's move on to curb flashing. Curbs greater than two feet by two feet are flashed with one continuous piece of EPDM membrane that is wrapped around the curve. We recommend using 60 mill. or reinforced EPDM membrane, which is stiffer and easier to work with than other EPDM membranes. Now let's look at the detailed procedure for flashing a curb.
First determine the proper size of the piece of membrane for the . The length of this piece must equal the total length of all four sides of the curb, plus four inches. The width of the piece must equal the desired flashing height, plus four inches. Be sure to add two more inches to the width if a batten strip on the horizontal is used for the based tie-in. Position the field membrane next to the curb and mark the corner locations.
Then cut an X between the marks. Pull the field membrane over the curb and fold back the four triangular areas. Then cut these triangular areas, so that four inches of the membrane extends up from the base of the curb. Place scraps of EPDM membrane or other suitable material under the four inches flaps. This will prevent bonding adhesive from contaminating the surfaces were later you will make a watertight splice.
Apply bonding adhesive to the exposed membrane and four inches up the side of the curb and allow it to flash off. Working from the adhesive side of the membrane, tuck the membrane into the angle change and work it up the wall. Install the batten strip into the curb, so that the fasteners are an inch and a half out of the break. Next, mark the piece of wall flashing for the application of bonding adhesive and quick prime.
Apply bonding adhesive to the appropriate area of wall flashing and to the sides of the curb. Keep in mind that if any bonding adhesive gets in the splice area, it could cause a leak, so it must be completely removed. Then, remove the protective sheets and mark the deck membrane three and a half inches from the base of the curb. Apply quick prime to the deck membrane, making sure to cover past the marks and to the area of the wall flashing that you marked.
Also, apply general purpose sealing to fasten the heads. After the bonding adhesive and the quick prime have flashed off, install quick seam splice tape one half inch past the corner of the curb and to the marks. Compress the tape with a dry quick scrubber pad and handle. Cut the quick seam splice tape one half inch past the other corner. Fold the quick prime portion of the wash flashing back and set the flashing in the center of one side of the curb.
Using the top of the curb as a reference point, wrap the flashing around the entire curb. Roll to the angle change and cut the curb flashing at the corners. Do not yet remove the release paper. Instead, set all four sides. On the deck, round all the corners and trim any excess membrane to expose one half inch of release paper. Remove the release paper and press the membrane into the quick seam splice tape.
To complete the vertical tape splices, fold the membrane back and apply quick prime to the splice area. Test the quick prime at the overlap. When it is ready, install a strip of quick seam splice tape. Flap the membrane. Remove the release paper and make the splice. Roll on quick seam splice areas with the silicone roller in both directions. Complete the vertical seam by installing a T join cover and a vertical joint patch.