Warm flat roof

[Uggie]

Forward planning a roofing project for the spring/summer.

We have a rear extension that I am converting into a new kitchen that has a cold flat roof that is giving me some concerns. The roof was recovered about 5 years ago and had new facias fitted. I decided to replace the extension ceiling as it was artexed and isn't really suitable for a kitchen, as I pulled the ceiling down it has revealed damp rotten boards that I'm guessing was caused by condensation due to poor ventilation. The beams are good so I have decided to replace the decking and coverings.
My question is.
Is a warm roof the better option? Someone told me that all new flat roofs are now warm roofs not cold. If this is the best option can someone tell me the best method and materials to use.

Thanks

 

[tony1851]

Someone told me that all new flat roofs are now warm roofs not cold.

Not so, but where possible, a warm roof is better because you avoid the tricky problem of ventilation.
The downside is that the thickness of the insulation (usually around 4 - 5") plus the thickness of roof joists + boarding makes for a deep, clumsy-looking fascia.

 

[Uggie]

Ventilation is my biggest concern, at the moment it has mineral wool rolled between the beams which blocks off any air movement would this have been better using a rigid insulation board?

 

[noseall]

A warm deck is the simplest and most cost effective solution, for a flattie.