Slab Heights Versus Elevation Heights

I've been struggling for a long time with a terrain and almost have it figured out but am still a long way from understanding what the software engineers had in mind when they designed the interface.

I think my question illustrates my dilemma.

I have an elevation region defined as -34" and I wanted to creates a concrete patio slab that sits at the same (or slightly above) the terrain. But when I enter -34" as the slab height its much higher than the elevation height with the same value.

Missing something. How does Chief think in this instance?

Is this what you are looking for?

http://www.chiefarchitect.com/suppor...?faqNumber=938

PERFECT Catherine, Thanks so much. My Terrain is built 20" below my floor height and that's the difference between my slab and elevation. Sweet.

Try Scott's video's at chieftutor.com.
He has done a lot of videos thinking out of the box. and not in the chief manual's.
There must be hundreds of videos there.

Set your terrain to "0" and just use terrain regions to get the heights you want and everything is figured off the "00" floor height.