How to make units don't "ghost" in some doodads?

[old]

There is a doodad called Rock Chunks, and the units can "enter" in the cusp of this doodad, i want to eliminate this, not only with this doodad but with someothers, like houses.

 

[Pyrogasm]

There's a whole section of doodads called "pathing blockers" for air, ground, etc.. Look at the list and you'll see them. Place them anywhere you don't want units to be able to walk.