roof vents

Hi there, I'm hoping someone can help advise. I've had two roofers out to look at my attic space, as there is inadequate ventilation in the ceiling void and therefore we've had issues with condensation collecting on the roof felt in winter and it being extremely hot in the summer. Both...

Hi I noticed most of the houses in the row have these on the roof. I think they are vents ? I'm wondering if I need them, but as I can see daylight through some areas of the roof it seems like it's well ventilated !