BryanRichards wrote:
a roof on the lines to this. any ideas.
If the roof is planar, it's rather easy : use the roof tool and see the help file concerning the edition of hatches | slab | roofs in plan (polygons edition by clicking the edge of the element and curving it), then cut the walls with the roof
If the roof is curved, you'll have 2 solutions (probably more) :
1. use the curved roof tools that will draw a series of planar roof connected to each other, then edit them in plan as for any other polygonal element, then cut the walls with each roof
2. use a library part to describe the vault, then use SEO to remove the unwanted part of this vault (by drawing a big slab with a hole following the edge of your desired plan view, for exemple), then use SEO once again to remove the unwanted part of the wall... this might not be possible as cutting a wall with a vault (GDL object) was still impossible in AC8.1RC4...