A single batten is fixed level with the top edge of the deck. Apply 30mm beads of trim adhesive to the batten every 300mm, rub the trim into place and nail through the top of the trim into the decking. Do not nail through the front of the trim. If a ladder is likely to be leant against a RIAB type trim for regular access to the roof, the trim will need to be reinforced to avoid deformation. The trim can either be doubled up by slotting a section of extra trim within the section where the ladder will be used or it can be reinforced with an extra layer of GRP laminate and then tissue to maintain a smooth finish. Alternatively, a wooden batten can be shaped and fitted into the ridge of the trim to ensure that it remains rigid.