Hi looking for some help I have a four in block flat my downstairs neighbours wont let me convert the loft to a habitable room. So im looking at check converting it into a nice storage room. At the moment its an empty shell I need to build a firewall too. I wont be putting a window in would air conditioning be ok instead. Also hoping to put in a pull down staircase. Any idea how much all this will cost neefs floored plasterboard walls walls insulated etc thanks in advance