I need to vent out the tumble dryer along a 2m stud wall to external. The wall is constructed of 63mm CLS timber. I was looking at cutting through the uprights with 54mm venting am i literally cutting it too thin as i guess im going to end up with a max of 4mm walls ifi cut the slots dead center. Or should i be using narrower 24mm ducting which im concerned doesn't give enough air volume? Thoughts appreciated.