How to make ladders -Use whatever force is used in the stock maps.
1 - Select a linedef
2 - Go on Action
3 - Select action 128
4 - Add set: Add
5 - Force - 15(can be a different number)
6 - Check "repeatable action"
7 - Down Up - you pick.
8 - Trigger - Player bumps
9 - Profit!