Housing in Barcelona, like other big cities, can be complicated, thus, we recommend you to start looking for an apartment or a room before your arrival to the city. The average costs of a room in Barcelona moves around 450€ per month, but it depends, of course, on the district you are looking in (you will find more information about the districts in the next chapter).
ESN Barcelona offers you the possibility to find flatmates and rooms in this Facebook group. On it, you are free to post whatever you need. There are also more Facebook groups for living in Barcelona.
Finally, for those who are not sure about sharing a flat or a room, you also have the option to rent a room in a student residency. There are many residences around Barcelona, and with different prices. If you are looking for a residence close to Universitat Pompeu Fabra, we reccommend you THS Campus or RESA, for UPF students only.