Having owned motor homes for over 10 years we have always endeavored to make it better. Dethleffs is no different.
We had a great time at Miranda springs when we all met and were able to swap ideas with one another.
I have owned our Dethleffs Comfort now for 7 months and the vehicle lives in a shed. I noticed when we were washing it that when finished i always had a drain waterline down each side of the roof in the front.When i climbed up i find that when manufactured they put a 2 inch wide strip across the front to help seal the roof and then put mastic across the gap where the water runs off the roof . This leaves about half inch if water on the roof and any dust etc washes down and sits there. Bee pollen is also known to accumulate and cause moss to grow in the dust.. Any van that lives outside will have more dirt stuck to the roof than mine.
I suggest that we all climb up every 6 months and use a good wash and wax on the roof and clean down.Open the vents around the shower and toilet vent and remove any leaves and pine needles that have become stuck there.Wash down the solar panels and also the TV dish. We have to remember we have a warranty on the roof and should check the roof periodically .
I would like DETHLEFFS when manufacturing the motor homes to put a smooth amount of mastic in this gap so as to not hold water .
I hope what i have written can be of help to you as we all wash our vehicles often but do not climb up on the roof.