Here are a few suggestions:
When arriving in Belgium, you have the possibility to stay at the Kot Erasmus for a few days in order to take the time to look for an accommodation. If you want to get a place in the Kot Erasmus, you must go on their website to subscribe online: http://koterasmus.be/
Kot Erasmus is a UCLouvain student assocations. You will be able to stay there a maximum of 3 nights for 5 Euros/night. They offer temporary dorms to give you the time to find a definitive accommodation, when arriving in Belgium.
Kot Erasmus opens on September 9. Arrival: before 16:00 unless you have informed them in advance of late arrival.
Go to the UCLouvain Housing Service as soon as possible (and every day) upon your arrival. Some UCLouvain housing are released early in the semester. There are several reasons for this such as students cancelling their arrival, finding another place to live or failing exams.
NOTE: Even if you don’t need to stay at Kot Erasmus, you are welcome to go their and meet with other exchange students and be informed of their different activities during the term.
A new youth hostel is opening in Louvain-la-Neuve in September 2019, see: Gite Kaleo MOZAÏK
Different youth hostels in the country. The nearest of LLN would be in Brussels or Namur, but if you search for 'auberge de jeunesse' you should still find more of them!
IBIS Styles Hotel, Boulevard de Lauzelle, 61 – Tel. : +3210450911 – Cost : from 71€/night.
For accommodation at the UCL Housing Service, upon arrival go to rue de la Gare 6. You should go there and check regularly, as rooms will get available every day. Contact person: Mrs Laurence Mairesse.
More information on alternatives to UCLouvain accommodations
We hope all this will help all the best!