Hi there - it's the opposite actually. The joint you see in the pictures is at the eaves, there is no gap at the ridge, growing to 1.5cm at the eaves.
There is no mastic visible internally. Externally, on one side it's totally normal sealing, along the edge of the external cover plate. On the...
Hi - I have exactly the same issue, it appears. Sorry to resurrect old thread but so many similarities, including the imminent house move.
I have the gap from bottom to top, it's about 1.5cm at the top . Same coming from the roofline down to the corner - no gap at the ridge, up to 1.5cm...