50mm is the minimum requirement to meet building regulations and it must be continuous. If your architect has passed the installation, then I would request in writing from him stating that 10mm and non-existent in places meets current building regulations.
I shouldn't think that he will provide such a letter, but even without it, he has not met his obligations, and futher action can now be taken. You should at least have something from him in writing stating that it conforms to current building regulations.