Roof overhang

[Archon]

I am trying to design a passive solar home using a 60 degree roof on the south side of the house.

In order to shade the southern windows in summer the overhang or eve needs to be about 3 feet deep.

If I tell the roof builder to make the overhang 3 feet it just extends it 3 feet long at the 60 degree angle.

How do I tell it to stop at the top of the wall and make the overhang 3 feet perpendicular to the wall? This would seem to be somewhat obvious but the program doesn't understand what I want.

I have attached a drawing of what it does on the left and what I want on the right.

[Archon]

Forgot to add I am using HD Suite 6.04.