￼This can be completed very quickly. It might take you 5 or ten minutes to create the spaces and link them to the site plan. You can check your house concept against the site recession planes (height in relation to the boundary). Checking at this early stage allows you adjust the concept. This gives you the information you need to improve your design.
Maybe you will move a room, reduce it’s height, change the room elevation. You can now choose to do all sorts of things. But without the 3D information you would not be able to fix your design.
If you are interested in finding out more about this concept check out my Short Sharp Manuals, available from http://www.archoncad.com/electronic-manuals.html