I was being chased by a zed, ran into a building and he did not appear to rise with the level of the floor relative to the ground outside. He clipped through the stairs and floor and was walking around about chest deep in the floor, still hitting me.
Zombies also confirmed to run through doors, walls fences and all other objects in path. {F28130} {F28131} {F28132} {F28133} {F28134} {F28135}