Q: I own a semi-attached house. Work needs to be done on the roof, but the other owner does not want to invest in the repair. It is not technically feasible to do only half the roof. Must he share in the repair?

A: Partners have a responsibility toward one another for necessary expenditures that can only be done together. Thus, if the repair is necessary, the other partner has to participate. However if it is only for enhancement, he can refuse, in accordance with the common practice (Rama, C.M. 178:3).

Even if the two owners are not actual partners, the joint need that can only be solved together forms a mutual obligation, similar to townspeople regarding taxes, or members of a building for joint needs of the building (Nesivos 164:1; 178:3).

Similarly, if there is a problem with the plumbing or electricity that affects all, each owner can force the other to share in the cost (C.M. 163:6; 170:1; Pischei Choshen, Shutfim 2:23).