problem model building rhino

[CateMako92]

Hello, everyone! I'm at first with rhino and I have to make a model to make and for 3d printing with rhino. I have a building that has a cover with different inclinations and I don't know how to do it. I tried to shape the cover with the surfaces and then extrude the walls but I do not know how to "eliminate" the extra part, the bolean union does not work. I can't even insert the control points so that I can lower the edges of the walls to the cover. How could I do that? Thank you. I attach photos.

 

[TECNOMODEL]

If the boolean doesn't work there's something wrong with modeling.
Is that "triangle" closed? Does the surface completely intersect the triangle?

 

[CateMako92]

I used the same curve for both extrusion and surface so it should coincide point and edges. In the end I solved with the command "tronca", I joined everything in a polysurface and hope that for the 3d will be fine. Thank you so much!

 

[TECNOMODEL]

It is not said, it depends on how the curves were made.