xtrader wrote:How would I cut the plasterboard off at the block work so it doesn't carry through
Depending on the stage of project development and the finished eaves detail I create two types of roof 1. The insulated section and 2. The structure outside the insulation.
Another option is to keep the single roof and "cut it back" with an eaves object e.g. a complex profile beam/wall using "solid element operations" (SEO).
AC has many ways to deal with these things according to how you want the final drawing to look and the level of detail you need to show.