Cold roof ventilation

[Patters1978]

Hi just a quick question

4x3m flat cold roof 175mm joists 100mm kingspan with 75mm airgap, on top of that are firing strips that run across the joists so roof has no voids.

Putting in 70mm soffit vents how many will I need on the 3m sides? Will I get away with 3 each side


Cheers

 

[Bonni]

https://glidevaleprotect.com/faqs/how-do-i-ventilate-a-cold-flat-roof-and-which-product-do-i-use/

The link covers ventilation.

Also, minimum Kingspan to meet building regs is 120mm.