The Perimeter wall was added in Alpha 13 (Version). Any prisoner digging an escape will always go around a perimeter wall if possible as it takes significantly longer to dig through perimeter squares.
Perimeter Wall is one of the four types of walls, the others being
Tip: Perimeter walls are typically a mid to late game upgrade after you have enough prisoners to support a decent income and need the extra protection against tunnel digging. Plan for them early by not laying power lines and water pipes where you will be placing them; but in early stages you can simply put down fencing to save money as your outer wall.
- Perimeter Walls are the strongest walls to dig under.
- Building a perimeter wall will create Paving Stone around the wall.
- Perimeter Walls do not block contraband by themselves. But using an outer perimeter wall and another inner wall (of any other type) with 10 spaces in between them is enough of a buffer to prevent thrown contraband. (have an entrance to the buffer area so dogs can patrol for tunnels)