I am building a new, flat ceiling under the old one (gap of 2 to 20" between them). I don't think the old ceiling is insulated so I will put loft insulation over my new ceiling.
Do I need to use vapour-barrier plasterboard to stop condensation forming in the space above the insulation? There is no ventilation here. Or is it better to use ordinary board so any moisture can get out?
I am hoping to just paint the plasterboard. Do I need to tape the joins or just use filler?
I will be putting 9W CFL spotlights in the ceiling. Can one cover a low energy CFL spot with insulation or should this be avoided to stop it getting too hot?