Thanks. I've got the flashing etc.but need to know if it is ok to cut through the concrete tiles around the lip where they hang on the battens. This is where the twinwall chimney would finish up, right on the batten.
I'm going to fit a freestanding wood burner with twin wall chimney and need to go through concrete roof. Unfortunately, having bought the twin wall pipe for a straight run without bends I now realise that where the stove has to go - min 340mm from the internal stud wall - there is a roof batten...