What is the ruling on taking out a loan with interest from a bank in which one has saved with the intention of obtaining an interest-free construction loan, especially given the need for housing and facing the bank?

This contract between you and the bank is forbidden (haram) because it is based on the principle of "lend me, I lend you," which is prohibited. Furthermore, the work of a usurious bank is based on lending and borrowing with interest, which makes you a participant in the sin. The usurious interest becomes forbidden to you unless you are poor and in need, in which case you should spend it on the general welfare of Muslims. With the existence of a new system involving interest on housing loans, it has become obligatory to terminate this contract. There is no necessity to deal with usury as long as you can live in rented accommodation or participate in home ownership. You must abandon the idea of borrowing with interest and invalidate the procedures that have been undertaken in this regard.