MB4 241a: Partitions Between Two Chatzeiros - part 2 (372:8-9)

If the 2 ladders on each side of the partition are 3 tefachim or more apart it's only considered a petach if the wall is 4 amot wide. The ladders have to reach to within 3 tefachim of the top of the wall (לבוד). What if they didn't make an eruv and both chatzerot have access to the wall?