Spiral parking

The question is trivial, but not obvious to me - how do you close this spiral curves to get a solid volume for the parking lot?

Simple extrusion does not help, because the level does not reach the ground

Spiral parking.gh (19.1 KB)

Hi -

As you can see in the cross-section drawing at the lower left of the picture you posted, the left side of that structure goes down longer than the right side of it. The same, though mirrored, happens in your Grasshopper picture.
If that’s not what you really are after, you could make the spiral continue further and then trim with a horizontal plane.

1 Like

Oh, why didn’t I think of it right away, it’s so simple! Thank you Wim, I worked with the drawings and did not see such an obviousness …