Roof skin lifting

[French Dave]

Hi all, while prepping my 2010 Chausson Flash 14, Transit based, for winter, I found were the over cab roof meets the van roof, the joint has a joining strip which I assume is sealed and screwed, I found an area about 6 to 8inches backwards from this strip to seem to be lifting from its inner boarding, you can press it down with the thumb. Any advice or tips.
Thanks all.

 

[WASPES]

I don't know on your van but swift vans used to do the same, I was told it's a floating roof and that is how they are made.

 

[French Dave]

That’s what’s seems to be the consensus Waspes, thanks for you reply

 

[ontheroadagain]

Our Elddis is the same.
On a cold day the roof is flat. On a hot day it is very uneven due to the expansion of the roof skin.
I was somewhat concerned the first time I noticed it.