I own a circa 1965 "Dorma style" house. In 2018 I had the wooden panels and felt roof replaced with UPVC cladding and rubber respectively due to the ingress of damp. All the lead work was also renewed. Recently water has dripped through the roof at the point where the vertical UPVC meets the slope. From outside everything looks in tact. I have had 4 roofers look at it. 2 said they needed to replace the cladding, 2 said the underlying felt was displaced. Prices ranged from £400 to £3000. Only one, the most expensive, took the trouble to respond in writing.
I don't expect anyone to be able to diagnos the issue without inspecting but perhaps some one could explain to me a) why the different diagnosis? b) how could UPVC cladding/rubber roofing materials deteriorate in such a short time? c) Why should displaced felt cause a leak, surely it's the tiles that keep the water out? d) Is there a professional roofing body/organisation for the customers benefit, not the roofers who I can refer to in order to start over with trustworhy tradesmen.
Thanks in advance to anyone with the expertise who has taken the trouble to read my long rambling post and respond.