Is it permissible to obtain an apartment from social housing through an installment plan over 20 years, with an initial down payment of 15,0 pounds?

The ruling on purchasing social housing depends on the system of its purchase. If it is free from usury and religiously prohibited elements, then there is no harm in it. However, if it involves a usurious transaction, then it is not permissible to proceed with it except out of a recognized, dire religious necessity.