Half Cylinder Prim Question

When I make the backrest of a chair with a half cylinder and add it to my inventory when I'm done and want to rezz it again, then it doesn't spawn on the ground like all the other objects I've made before, it spawns a bit in the air. The thing that puzzles me is that the chair seems to spawn on the other half of the cylinder, the invisible part that reaches beneath the legs of the chair, like it's still there.

My question is: Is there any way that I make make the chair spawn on the ground and not in the air when I take it out of my inventory?

Thank you

A script could shot a bullet downwards that tells it where the ground is to place it just in the right height.

A script can read the height of the land and the height of the ocean water at any place of the sim and place its linkset according to it.
It could scan if there is a prim below it before doing so, so it will not place itself in a prim-floor.

it is NOT worth the efford. just move it in the correct height manually, because it will NEVER rezz at the right height position.

mostly this is caused by the bounding box not being the same as the cut prims size. simple solution, cut the other end. have the missing cut piece above instead of below and it should rez on the ground/surface normally instead of hovering. sometimes this is cause by having a cut surface prim, when you try to rez on it it , it acts very odd at best.

I have the same problem with a highly cut torus in a chair