Slab edge angle and direction

[Josh Verran]

I'm attempting to use the slab tool to cut away a site mesh to allow for retaining.
The batter is 30° and starts 1.0m away from the building edge, starting 225mm below floor level.

I've drawn in the slab to be used as the operator, offset by 1.0m, dropped 225mm.
What I am hoping to do is add a 30° angle to certain edges, then as I increase the depth of the operator slab, have the batter cut up and outwards away from the building.

What I am getting is the opposite, when I enter the angle and depth the edges are sloping inwards and downwards.
I have set the reference plane to the bottom, however this only affects the offset to story.

Hope that makes some kind of sense.
Happy to clarify.

[Laszlo Nagy]

Yes, this is how it works. The edge slope is always measured from the top surface of the Slab, regardless of where the Reference Plane is positioned.
I think this may have historical reasons. There was a time when Slab edges could be sloped, but there was no Reference Plan setting for Slabs. Then Slab Reference Plane feature was added, but I guess this modified behavior of Slab edges was not implemented.

I agree that this would be the most logical. I would expect that the Slab outline that I define is valid in the Reference Plane, and Slab edges and geometries should be generated based on that.
I think this was even wished for at some point on this forum.

[Barry Kelly]

Look closely at the icon and you can see you are setting that inside angle under the of the slab (and yes it is always to the top surface as Laszlo explained).

90° is vertical.
30° will sloe inwards as you have found.
150° will slope outwards.

Barry.