A 110mm (4inch) dirty great big hole was cut into the rubber membrane! In the back left corner of the roof is where we have the rain water drain pipe coming up through the roof and today the major operation of cutting into the waterproof skin was made and fitted the special flappy rubber flange connected to a piece of 110mm plastic pipe which slid into the waiting pipe behind the hot water tank. The special rubber had a coating on it which very strongly binds to the rubber roof membrane (after the roof membrane was treated with a rubber primer and scrubbed!). the final seal was extremely sticky and very strong. There was only one chance to get it right! And it was ok! Phew!
Roof drain hole
A stainless steel mesh was coiled up and stapled together using stainless steel staples (naturally) and carefully jammed into the hole to provide a filter to stop leaves, moss and other larger bits and pieces from floating into the drain system.