http://www.graphisoft.com/archiguide_archive/ArchiGuide_Online_6o/issue15/roofs.html#vault
Before you start, set your magic wand to 18 or 36 segments per arch, and best match.
If you want to use the Custom profile wall as a roof, that will yield a smooth curve, that also trims any walls beneath it. Do a half curve.
You have the hook, the bait, we showed you the river. Now fish
Djordje
ArchiCAD since 4.55 ... 1995
HP Omen