Ok I did say I would offer another tip about putting holes in the ACA Roof Object.
Well the Truth is you can't. Be nice to be able to wouldn't it!
UPDATE: Best practise shown in my video on youtube here.
Whole Roof Object Playlist here.
But I can get you close enough to get the job done in an efficient manner without resorting to slabs.
Here I'm going to show you how to create....
Dormer Roofs (ok this is another Sergej tip and he keeps telling me I have to share this one) but this technique could be used for adding any hole.
You know this is a great trick and the funny thing is that Odin Cary showed us all years ago in this page in his instruction set. I did read it but didn't understand the potential. This method improved and simplified in the next release after he wrote his article and I show here how simple it has become.
I've shown a simpler example so hopefully together we can show you that this could be a great option to create that Dormer roof or other complex roof with a hole for your next project. Odin's example uses the model explorer which still works and may be easier to edit but it's no longer necessary.