Bonding Overlapping EPDM sheets
When attaching 2 overlapping EPDM sheets, mark where the edge of the top layer is and then mark out an additional 5mm. This overlap will form the “bleed" so that there is no place for water to get in and it is much more difficult for anything to lift up the edge, even slightly.
Once this is marked, fold back the overlapping part of the top sheet and secure it with a weighted object like your metal roller.
Using a scouring pad as a brush, begin applying a very thin layer of the Primer Adhesive to both sides of the join.
Using the scourer means that the talc like powder on the surface of the EPDM mats will be removed and the Primer worked into the surface well.
Make sure that the Primer is applied up to the previously marked line, including the “bleed"
Leave it for a few minutes until the surface is tacky but not sticky. There should be no pools of liquid Primer still there. This allows the gas produced in the reaction between the surfaces to vent off. If you do not allow the Primer to dry, the gas will be trapped between the layers and will leave visible bubbles.
Once both sides are dry, keep them separate and take your strip of Pressure Sensitive Seam Tape, keeping the plastic on the top surface.
Leaving about 2-3mm of Primer bleed visible to the side of the tape, start at one end and, holding the tape to ensure it doesn’t touch the primed surfaces, press the tape firmly down,
Now, remove the protecting plastic and you can unfold the primed top sheet and, while pressing towards the open side with a flat hand, allow it to contact the top surface of the seam tape and press firmly.
There should be about 2mm of seam tape visible as a “bleed" and then another 2-3mm of Primer bleed next to that.
Use a small metal roller to press down and roll side to side to squeeze any bubbles out.