Can someone please tell me how to change the orientation/direction of a bounary layer?

You know that it makes sense to talk about BL orientation only for interior faces (on walls you cannot change it, there is only one possible position). So if you want to attach BL mesh on an interior face and the first left-click isn't satisfying, simply click on the scroll and the BL will shift on the other side of the face.

Best wishes, Razvan

Thanks for that Razvan, I've got it working now.

John

Anytime, John.