External Corners

A step-by-step guide for when any part of your roof abuts an external vertical corner, such as brickwork, or a skylight.

Step 1: Firstly, before you flash your corner, you may need some guidance on laying your EPDM around any corners – see here for more info.

In short, to go around the external corner, your EPDM will need to be cut at a 45 degree angle from the corner back towards yourself, creating a v-shape around the corner. You will next need to bond your EPDM to the vertical & into the wall chase if applicable – β€˜EPDM to walls or verticals’.

Step 2: You will now be ready to flash your corner, with 2 separate pieces. Each piece will wrap around the corner 75mm. 

Your flashing will also need cover 75mm past any areas your EPDM isn’t bonded to. 

Using your chalk/crayon, mark 75mm onto your deck, and 75mm past the top of your v-shape. 

Step 3: Cut your 2 pieces of quick seam flashing to size. Each piece will fit either side of your corner, overlapping the EPDM by 75mm & also work around the corner 75mm. 

Allow approximately 10-15mm at the top to work into your wall chase if applicable.

Using your Quickscrub pad & handle, apply an even coverage of Quickprimer plus to the area within the chalked area, plus an additional 10mm. If applicable, using a small cheap paint brush, apply into your wall chase.

Step 4: When your primer is touch-dry, smoothly mate one side into position, starting at the top (allowing the 10-15mm to work into a wall chase) and working down. Before you mate to the deck, wrap your 75mm overlap around the external corner, then mate to the deck, smoothing the corner out.

Using your Silicone Rubber Roller & Penny Roller, work in the flashing. Work flashing into wall chase if applicable, or onto your skylight kerb if applicable.

Step 5: You will now need to apply primer to where the second piece will overlap the first piece you bonded. Complete this, then once touch dry, apply your second piece, same as the first.

Use your Silicon Rubber Roller & Penny Roller to thoroughly work in.

Step 6: On your exposed flashing edges, neatly apply a bead of Firestone Elevate Lap Sealant.

If you are fitting an L-shaped wall trim, you can now continue to install this, as seen in steps 6 & 7 here