Flat Roof and Insulation Advice

[Pete]

I'm just about to get the felt on my flat roof replaced. I mentioned to the roofer that it would be good to have better insulation. He has suggested adding a vapour layer and an insulation on the top deck.

Having thought about it, is it going to do any good? The roof consists of an upper deck with a 'void' of about 18 inches before the lower surface which I think is made of chipboard. There is an access hatch to the roof from within the house. When it is windy, you notice a pretty strong breeze if you pop you head into the void. Whether this is just for ventilation or whether we need some repairs done, I'm not sure.

So if there is such a breeze in this space, isn't insulation that is above this a waste of time? I would have though the insulation should be in the void although this would be more difficult to do.

Any thoughts appreciated.

Pete

[JK]

Sounds like it.

Our flat roof insulation consisted of rockwool battens. We took down part of the ceiling and slid them along between the beams, resting directly on the plasterboard.

Ventilation is important, you don't want rot, but there's no reason to have a gale blowing through, it will only make it harder to keep heat in. You should find the source of this and control it.