You can use a func_detail for the angles AND an area portal under them just fine. Of course the area portal just needs to be touching the walls below the func_detail.
On a small house like Total_Mark's though it wouldn't do much good as you could probably see all outside vis-leafs from anywhere inside it.
I also agree TotalMark, that you should just func_detail the whole thing. Cut down on visleafs and area portals.
But I'm curious what you are trying to achieve with the blue brushes. If those are hints you are only adding at least 8 polys, 4 + leafs which all takes more to compute then if the house was just a func_detail.
It's always hard to say performance-wise by a screenshot alone but I don't think any of that is helping more than it's hurting.
Also, you should bring those corners together. Each of those indents in each corner is making a new visleaf. Each of which most likely extends half way across the courtyard knowing how Hammer optimizes. And adding the hints there doesn't fix it, it just cuts them in half and makes more leafs.
Plus you'll cut down on poly count if you bring the corners together. Even if you have nodraw the floor is being split into more polys than needed because of that.
Hints usualy dont even matter alot for angled roofs unless ingame the optimizing failed. But if you want to be 100% sure that it gets done well only use hints for the roof itself and use only 1 brush for it (if you use more it usualy makes the compile take longer). The most important thing is to have everything done smooth without any gaps. As long as you keep it to nice brushwork you wont get any problems from it (where vertex usualy keeps the brushwork nice unlike a simple rotated brush).the roof is made using vertex tool yes.
alias you think i should just make it triangular visleafs above/below the roof? using hints to define the shape of the visleafs in advance?
If it were detail all those models would be drawn, I wouldn't be able to portal it off.