Joining your EPDM with 3 inch Seam tape

Step 1: Ensure the EPDM joints are straight, with the top layer overlapping the base by 100mm. 

As a general rule if applicable, position the top layer of EPDM where water run-off will run over, & onto the bottom layer.

Step 2: Using a White crayon or piece of chalk, mark a straight line 20mm past the 100mm overlap. A baton or strip of 18mm timber will be good for this.

Step 3: Fold back the top EPDM rubber fold. 

Using your Quickprimer Plus, Quickscrub pad and handle, apply an even coverage of primer, ensuring no puddling, to the area marked within the chalked area & to the underside of the folded back EPDM.

Wait to go 'touch-dry'. If your finger moves through the primer or is stringy - it is not ready.

Step 4: Once ‘touch-dry’ (must not be wet), it is time to apply your Seam tape. Starting at one end, with the brown paper side on top, start applying the Seam tape to the primed area on the lower layer of EPDM.

The seam should run parallel & flush to your chalked line. Keep the seam tape reasonably taut, without stretching, to avoid pockets during application.

Once applied, use your silicone rubber roller to work in on top of the tape.

Step 5: Flap your EPDM back over, about 20mm of the brown paper should be showing past your top fold.

Next, starting at the leading end, gently peel back the brown paper whilst smoothing the EPDM into place, on the top side of Seam tape with your other hand as you go.

Work in once adhered, using your Silicone Rubber Roller, working out any air pockets as you go.

Step 6: If there are multiple joints, such as a T-joint (where a seam joint meets an adjacent seam joint). Firstly, under the top fold, there will be some excess of EPDM on the original rubber which could create an unseamed pocket for ingress. Cut this back at 45 degrees so it can be bonded.

Step 7: Then follow previous steps to complete your Seam joint.

Step 8: For reinforcement of this area, cover this area with a patch of 9’’ Quick Seam Form Flash, approx. 150mm x 225mm.

Mark the area to be primed with your crayon/chalk. Apply your primer with an additional 10mm around the perimeter.

Step 9: Once touch-dry, apply your Form Flash, working into place evenly to avoid air pockets.

Work into place using your Penny Roller & Silicone Rubber Roller.

As an extra precaution, you can apply a neat continuous bead of Elevate Lap Sealant, taking care not to have your bead too proud, causing potential sitting water.