Distinguish existing structure in remodel

[slidnbob]

I'm using HD Pro 2014 to design the addition of a second floor to an existing house. This new floor is not a full second floor, it just covers a portion of the existing structure. Also the area on the first floor beneath the new floor is being reconfigured. The rest of the house will be unchanged. In the drawings I will submit to the county building department I want to clearly differentiate the new/changed portions of the house from the areas that are unchanged. how can I best do this? It seems to me that one way to do this is to change the fill style of the new walls, to set it to a different color. Will this work? Is there a better way.

Thanks in advance