Walls and fences
Max slope = (3 * √skill) + 10
Note: Maximum slope is rounded down
Alternatively, to find the skill required for a given slope, use this formula:
Skill = (slope - 10)^2 / 9
This answer gets rounded up instead.
Note: These skill limits do not apply when building small stone walls at cave entrances.
Two corners going into 1 corner can result in a "hidden edge" being steeper than 40 making it unable for animal driven carts to walk up.
The sum of the north-south and east-west slope must not exceed 8 dirts.
For example if a tile has a slope of 6 dirts from north to south, the maximum slope from east to west is 2 dirts.
Another example, the north to south and east to west slopes may be 4 dirts steep each.
When tunneling to create a new mine entrance, the maximum slope of the rock tile you are tunneling into is 270.
The maximum slope you can dig on is 3 x [your digging skill]. E.g. A skill of 50.25 in digging means you can dig on, or adjacent to, a slope of up to 151 dirt.
On PVE servers, the maximum slope you can mine on the surface is 3 x [your mining skill]. E.g. A skill of 50.25 in mining means you can surface-mine on, or adjacent to, a slope of up to 151 dirt.
On PvP servers, the maximum slope you can mine on the surface is 1 x [your mining skill].