Extend Sub-Grade to Bottom of Floor Slab

[Firmso]

Hi, I have a topo surface that is lower than my ground floor line by 4 feet. I want the topo cut pattern (earth) to show extended (or attach) to the underneath surface of the ground floor slab. Is this possible?

Edit : I do not want to use a Pad as floor, although the earth pattern extends to the slab bottom automatically with the pad tool. (why can't a Floor?)

Thanks in advance

[Dimitri Harvalias]

Why not use a pad? It doesn't have to be your floor. You can create it as a very thin pad (1/4"), set the elevation to the underside of your floor slab and then the topo will adjust. At that thickness you can either ignore it or hide the category in the view.

[Calvn_Swing]

And, Make the Pad some material you will need. Like Gravel, or some kind of Moisture Barrier. That way you're also getting some use out of it.