OUR caravan engineer does a set damp test every year and he has done all but one of our services since 2003 when we got the caravan The meters that record an amount of moisture as slightly better than the noise producing one in that it quantifies the moisture But I understand what Mark means about false positives as some materials have lower resistances so produce a false positive Pictures I agree with as by superimposing the images you can see progress Also if your van is a 2008 that means it's 6 year damp cover is up check out your insurance about damp too
Thanks Mark there really isn't much to take a pic of and im not sure the camera would show it, I would have to peel it back with my hand, Its only peeled about half an inch all the way along the top of the cupboard. Oddly though its only the two corner units and not the one across the middle that joins them. I will take a pic for you but im not going back out for a week or so to give my de humidifiers a chance. I personally think and hope that its caused by condensation through 5 of us sleeping with the heating on etc.