Hi: I'm building a second floor deck above a first floor porch, it has an epdm rubber membrane already installed, the decking will end up sitting on pt sleepers. The pt rail posts come up through the rubber and the outside corners of the rail posts still need to be flashed properly. Is it better to use standard epdm membrane material for the outside corners and apply my own adhesive, or better to buy pressure sensitive material that already has adhesive? Do I need to apply 'primer' in either case? I'm reading about 'membrane cleaner', 'primer', 'adhesive'(both solvent and water based). I'm a retired carpenter, no experience with rubber, wondered how a roofer would approach this? This is a small deck with only four rail posts, so don't need much as far as materials. There's no place nearby that sells roofing products, anyone recommend an online store that might sell smaller quantities of things? Thanks