I've never seen so much black mould and condensation and moisture in a new flat roof.
In this video, I look at how this has happened and the way to resolve the problem. With cold roof construction, the through ventilation is the most important thing even more important that the VCL vaper control layer.
Vaper control layers only controls the migration of moister into the roof structure; if there isn't the ventilation to clear what gets through then, you have a big problem. Now that this roof has been building the owner has to decide on how to redo the roof to put it back as a cold roof or to try and convert to a warm roof. Warm roof is definitely the way to go however this sill rais the roof, and that may need permission from the local authorities as this could be a planning issue.