Hiring/Renting: Subletting a Portion of a Rented Property
Practical Laws of Islam as per the teachings of Ayatullah Sistani
Ruling 2193
If a person rents a house or a shop for one year for £10,000, for example, and he makes use of half of it himself, he can give the other half on rent for £10,000. However, if he wishes to give the other half on rent for an amount higher than what he rented it for, for example £12,000, he must do some work on it, such as making some repairs.
-Ayatullah Sistani, Practical Laws of Islam, Hiring/Renting (Ijarah)