Does anyone know a good way to push a 4m lenght of flexiable ventilation tubing throught a flat roof space please. The tubing is 15cm, in diameter, and the roof space is 15cm ! Ahhh..... please help, I was thinking to cut a hole on the ceiling, where the tube will eventually come out, and push the tube in from this end, and attach maybe a piece of string and have a friend gently pull it from the other end, but my fear is that the tube may rip open.