Why? The site plan is generated from the first floor. The roofs are only seen in their entirety on the roof story. The only way to get the roofs on the first floor is to draw (trace, copy/paste, whatever) them. We don't like drawing things. Especially things that can draw themselves, especially things we have to keep checking in on to see if they are drawn properly. We want a top view drawing that maintains itself like any other model view.
There are two ways to do a top view so that it remains live: A plan view from the roof story (like the roof plan itself), or a hidden line top view generated in the 3D window. I think the 3D method is better. The 3D view can show elements of all stories, while the roof plan will use the story settings of individual elements. There's no issue of display order in 3D. A roof plan drawing would have the advantage of generating a little bit quicker, but that's not enough to change my mind.
The templates are set up with a view in the 3D views folder called 'Top View'. You might need to change the scale of this view; obviously it needs to match the scale of the main site plan. The other settings are:
• Layer combination: x Shoot Roof Plan Top View. (Update: I changed the name for clarity.)
• 3D Projection Settings: Top view, azimuth=270 (Camera at bottom).
• 3D Window Settings: Internal Engine, hidden line, vectorial hatching off, shadows off, transparency off.
The trickiest part about the two-drawing approach is aligning the top view with the main site plan. For some reason, we don't get the snap points (midpoints, e.g.) for lines within drawings, so we can't line up a roof edge midpoint with a footprint line midpoint. Fortunately, for most purposes, good enough is good enough. Zoom in and eyeball it. Make it look good. Remember, the dimensions will be to the footprint, which is drawn precisely in the main site plan drawing. If you do need a precisely placed top view, you'll need to place some temporary alignment elements on the first floor.
Make sure the top view's drawing element is set to have a transparent background. The pen set of thew drawing should be Layout 1/8", which turns the heavy lines a little less heavy.