Thank you both for replying to me, apologies for just getting back have been on leave the past week.
@Matt Panzer Have attached the file below, HTH
@Alan Woodwell Thank you, i've got it modelled using roof faces currently, is definitely much easier as you said. There's just instances where one roof face will be intersecting two different wall types - I was having issues getting the component joining (I think that's what it's called, the ones you set in the roof style menu) to work, and the settings given by the slab tool are much easier to use to achieve what I want. We're in the technical design phase for the project and i'd like to get it all set up properly to minimise the amount of masking I need to do in 2D; i'll give the roof face binding another go though.
Thanks again 🙂
Flat Roof Drainage.vwx