This detail is on a Parapet junction with a flat roof, it consist of a couple of walls, floor, roof, hosted profiles and some line work. The principle is there is a cavity external wall at the lower level that has a wider innerleaf of blockwork/CMU, there is then a suspended concrete slab that rest or is supported on the innerleaf. The external leaf extends past the slab and joins with a parapet wall that is slightly wider, the roof build up consist on concrete screed laid to falls, insulation and single ply membrane which sits on the concrete slab. You must note that both the floor slab and roof build up will be drawn in plan so it is important to consider where the roof starts and stops considering it will have falls/slopes which could mean you detail or levels might not work. After you model the roof you should cut a couple of sections to see if you roof detail is working and then delete unneeded sections. Below is a free hand sketch of the detail and list of components which I think are in the detail.
From the detail you note that I’m modelling the concrete capping as a swept wall profile, for these types of objects you generally pick a top corner of a wall (on one side) which means you need you offset the profile to one side, see sketch below for detail.
Next blog will be the video tutorial, hope to have it posted by next Sunday