Walls are an extension of deco objects with the only difference that they can block paths.
Because walls are an extension of deco they share the same [deco settings](deco).
The block settings will toggle which sides of the object should block paths. If that side of the object is placed between two paths, they will not connect anymore. A white cross will appear on the sides of a wall that are blocked.
Height: the height of the wall. Usually it should either be 1, 0.5 or 0.25 to match the games default walls.
Garret made a fancy guide on how to make walls fit with the rest of Parkitect.