The general rules about a contract of rent can be found in the Belgian Civil Code.
On top of that there are 3 specific contracts of rent, about which there is special legislation:
1. The contract of rent of agricultural land
2. The contract of rent for a commecial property, which involes contact with the general public.
3. The contract of rent about the home which is the primary residence for the tenant. .
This page only contains some general information, which can help you to understand law. For complicated legal advice it's best to have a lawyer who knows what you need.