Ventilation in flat roof

Firstly you need ventilation into the roof space from outside (vented soffit or small circular vents cut into fascia board in between each joist) and you also need 50mm gap between top of insulation and underside of osb board, with nothing blocking the airflow between the vent and the 50mm gap...... hope this helps

Putting vents into facia and soffit boards will not create an air flow as the rock wool will be blocking the airflow,what i suggest you do,cut into flat roof in several areas and fit pipe vents this will allow moisture condensation to disperse leaving your room to breathe,obviously the pipes would have caps fitted to prevent and water ingress,hope this helps,kind regards mike

You also need a continuance vent 25 mm away from back wall sitting on a 6” strip of osb board fixed independent from rear main wall and a searies of holes drilled behind new osb board in to old roof line , refelt new osb board onto exsisting roof coverings and fit a new lead flashing fixed in rear wall and dress down over new vent strip .

ideally rock wool is not great for insulation space between flat roof especially with soffit vents as it creates thermal breaks and could potentially make the room colder even though this would would stop any moisture build up, the best solution is 50mm kingspan fixed to the underside of the joists and 100mm kingspan between the joist and 50mm gap between kingspan and osb board, air vent/soffit vent for circulation of air the vents to be installed to the end running parallel with joists, this would stop any thermal break and create circulation of air flow between rafter and osb, this solution would create air floor stop any moisture build in roof space and still leave the room meeting the adequate thermal values

All the above answers are factually incorrect as is your roof. If you have appliances In a utility room then I would assume that you also have heating to protect your white goods. This then comes under Building Regulations C&L 2010 plus the BS for a warm roof to comply. No warm roof should be ventilated. You have a cold unventilated flat roof which will be cold in winter giving rise to condensation leading to premature early failure. KR Drew