I have a bedsit above a double garage. The radiators warm it up well but it goes cold really quickly once they are off. I would like to insulate the garage roof below as you can feel cold coming from downstairs. Unfortunately the garage roof is asbestos board apparently so cant be drilled and filled with insulation balls. Also the room has a fitted carpet onto chipboard flooring so not food for pulling up and filling from above. Would insulation board stuck to the roof be any good? Thanks!