Scaling an object with "even thickness"

Sorry for the title, I’m not english native… :slight_smile:
Basically I build a mesh representing an exterior wall of a building (actually it’s a house editor), then combine meshes and instantiate a new gameObject with flipped normals to represent internal walls.
What I wanna do is to scale the internal wall to simulate the thickness of the building, something like the Inset tool of Blender. How could I do?

You can use the inverted normal vector3 of the outer wall and combine if with the required thickness value to find out how far the vertices of the inner wall have to be moved.