Mezuzah in Office Building
I rent space in an office building [owned by Jews]. I put mezuzos on my office. What about the entrance to the building and the entrance ways and hallways [with doorways] I pass through to get to my office. If no one else cares to put up, am I obligated as a renter in this building?
As a partner renting space in the building, there would be an obligation to put a mezuza on any doorway you use. However being that this is really the joint obligation of all the renters in the building, you would not be obligated to spend your own money to purchase all of the mezuzos necessary. This is included in what the Rama O:C 656:1 codifies, that one is not obligated to spend exorbirtant amounts of money to perform a positive mitzvah. This includes any spending beyond the norm of that mitzvah in that situation. So while a pair of tefillin is costly, that is it’s price. Mezuzos in a joint building however should only cost a small percentage to each renter. In any event this is a “ptur” from paying. But being that the criteria for a mezuza are present, it would be a midat chasidut [commendable practice] to spend the money and affix mezuzos.
In offices and store settings, no bracha is made on the affixing of mezuzos, see Shulchan Aruch Y:D 286:11, and the Taz [s.k. 10] and Pischei Tshuvah there. If there are non Jewish renters, no mezuzah would be needed as in all cases of shutfus akum.