I’m doing some refurbishment work in my downstairs cloakroom which included repairing a damaged ceiling. The room is part of a front small single storey front extension. There is a flat roof above. On removing the old ceiling there appeared to be only half the amount of insulation above the cloakroom. I’m looking to reboard the ceiling but just wanted to check whether I can simply fill the space the the same type of insulation of whether there was a better option whilst the ceiling was down?