So I am replacing the ceilings in the dining and front room as they are covered in artex (which I hate - but gotta love the 70s and 80s) and I wish to fit downlighters, and they have cracks in them as well. I am happy with replacing the plasterboard (going to use tapered edges so I can tape and fill them) as well as the electrics for the downlighters. My question however is this. I wish to put some insulation between the joists to firstly, dampen the noise of the kids screaming at their computers but also to just help keep the house warm(er). What insulation should I use for that? The joists are 44x175. Would loft insulation be ok? What thickness would be ideal to use as I assume I would still need to leave an air gap? Would insulation boards be better as they obviously wouldnt sag and again, if so, what thickness of insulation boards would work without paying for extra thickness which wouldnt really give more of a gain.