Q: I share a hallway with my neighbor in a two-family house. He likes to leave his bike in the hallway, and now wants to install a bike stand. Can I prevent him?
A: Partners are required to use the joint property according to the common custom. Thus they are allowed to leave in the hallway items that partners typically do. Other items cannot be left there unless the other partner gives permission or it is something that he is not particular about (C.M. 161:5; Shach, Y.D. 226:8).
If both partners want to use the area simultaneously and there is not sufficient room for both, such as a one-car driveway, they should take turns. Even if one partner used the area exclusively in the past, the other partner cannot demand to use it now for an equivalent time, but they should divide evenly from now on. If they cannot agree who should use it first, they should draw a lottery (C.M. and Rema 171:8).
Permanent fixtures may not be installed without permission of the other partner (Sma 140:22).