Water under floor carpet

[KGCali]

The original front part of the roof can suffer from aluminium corrosion (blistering) and VW used to replace it but due to the expense they now cut out the corrosion then fit a plastic cowl over the original roof which is sealed to the old roof with mastic but this has been found to crack and allow water ingress so from 2019 they have improved the mastic to prevent this (hopefully)

 

[Kjetil]

Great explanation and pictures! This is obviously not my case since I still have the aluminum roof front, with some (only a few) corrosion blisters. The pop top has more clear aluminium corrosion in the corners, but I don’t find that as an issue.
Fantastic that VW replaced under warranty after 10 years.