Minecraft wiki entry for Metadata_variants, associated text: Ladders also used block metadata values 2, 3, 4 and 5 to determine their facing direction. As a result, ladders placed with data values 0, 1 or anything 6 and above exhibited behavior atypical of normal ladders. Notably, they would appear to readily switch what block face they were attached to (sometimes seemingly randomly, but could be controlled by looking at a valid ladder, in which case they end up switching to whatever its hitbox was), which could be seen through their wireframe hitbox and their collision box. Initially they would be full cubes.