Warm roof

Hi there,

I have recently had insulation added to my flat roof (north facing) with insulation and felt laid on top of my exisiting roof, so as to provide a warm roof solution.

My question is, that before this it was a cold roof. Now should I remove the rock wool insulation in the joist between the ceilling and decking or leave it in place? I'm quite happy to rip ceiling down and put up new boards so no big worries if I need to.

Also under the fascia on one side of the roof is an air gap with mesh over it, I assume to let ventialtion in the roof space. Can this now be sealed up or do the joists and roof space still need ventialting.

Obviously I don't want to have a warm roof and then impead it by having the cold roof legacy stuff still in place.

Cheers

hi from what i understand it should have been done through building regs,also yes remove rockwool.i think i am right as this is what im doing at mo

Yeah I thought it was the case.

I think the idea of the cold roof is that the cold point is above the insulation and needs ventilation to stop condensation on the decking & joists?

Where as with a warm roof it doesn't need ventilation because the cold point (dew point?) is kept outside of the roof structure? hence the roof is warm - warm roof perhaps?

What I don't want is to have a warm roof and then ventialte it needlessly and make it cold! I will definitely remove the rock wool anyway and probably seal the air gap and hopefully that should be fine.

Bit annoyed that the roofing company didn't say this, but I guess I should have specified it.

Warm roofs don't need ventilating.

I would leave the existing insulation in place to increase the whole insulation value of the roof.

The air gap is not going to do much, so blocking up vents is not going to improve insulation by any significant amount, so not worth the trouble IMO.