Ceiling Vapour Barrier required?

booooonzo

Hi,

I am redoing the loft insulation in our kitchen ceiling.
It's a studded out room sitting 50mm out from our old stonewalled, single pitched tin roof garage and the ceiling is just a flat TnG pine job with 100mm of fiberglass

I've bought 100 & 200mm earthwool & want to re-lay it all but there is no vapor barrier in place.

Do I need one? if so how would i do it as the ceiling is in place and has 6 down lights. (have bought thermal covers for these.

The ceiling has all been caulked and painted with 4 coats (2 primer/2 top coats)
Would this act as vapor barrier?

thanks for your help

BryanF

how are you installing the insulation? For above, removing the roof? Yes you have a vapour barrier in the warm side of the insulation. How you install it now, is down to how complete you can seal from the house to avoid condensation in the roof space/timber’s. If your insulating from above, could you go with rigid insulation over the joists (vapour barrier underneath), then breather membrane, vent space/battens and roof covering

booooonzo

Thanks Bryan,

There is an access hatch in to the attic and some crawl space. So i had planned to insulate there. The ceiling joists are at 400 centers and 100mm deep so had planned to put the 100mm earthwool between and the 200mm running acorss ways.

I don't know if there would be room to do the Ridgid option but might look in to it.
Im guessing the vapor barrier is a nesessaty?
Is the breather membrane just to stop debris from the roof?

BryanF

Just insulate and make sure you leave attic space ventilation.

booooonzo

cheers, went with none and have left good room for ventilation.