ground sections - existing project

[Stefano.bp]

Hello everyone, I looked for the topic but I didn't find a post about it.. I tried wrong.
I must represent works that count in a leveling of a wall of cinta and in the partial leveling of the above ground.
I have created a project surface with leveled region, are ok, but in section overlap the reasons for demolition and construction.
(in the attached image I have eliminated the demolition of the earthennus but as it is known the red overlaps to the existing surface.
In fact, I have to have in red only the excess beyond the existing...it does not do with the topographic surfaces, does it? I don't know.
How could I proceed? . .

 

[Tristan]

controls the phase filter used in that view

 

[Stefano.bp]

Meanwhile thanks, the phase filter is comparative > project status, as read in image, which is actually what I want.
the fact is that the project surface starts from where even the existing one that remains in its place.
if I activate a demolition, in the state of project for the existing surface (the one at lower altitude), it happens worse you see yellow and red overlapping in this way that only means that the objects overlap.
in no way can I give the thickness to the project surface starting from the existing one... I would say no only the higher points....
I accept advice