Dr. Monzer Kahf, a prominent economist and counselor states: “Necessities are things that create a substantial harm, if they are not available, to either of the five fundamentals that are: life, religion, mind, property and posterity. I don’t believe that a case wherein someone has shelter is a necessity. But wait a minute!
However, in some cases, it is not necessity that matters, it is rather reasonable convenience (al Hajah) if it applies to a large number of people! This is called in Islamic literature “al Hajah al ‘Ammah” that is convenience that encompasses many people. Taking mortgages in some countries is about the same for most Muslim families in the UK, USA, Canada and many other countries in the West. Such a Hajah ‘Ammah is given in our religion the same treatment as necessities that apply to individual persons.
According to the Fatwa of the European Fatwa Council and the Fatwa of the Second International Fiqh Conference held in Detroit the Fall of 1999, a Muslim is allowed to take a conventional mortgage because the Islamic one is not available to them.