Massive condensation behind roof liner

[Mark and Mindy]

I want to install a 4G roof antenna for a MiFi which will involve making a hole in the roof of the van and so today I went about the potentially destructive task of removing cupboards and trim in order to get behind the roof liner. At one point I could get my hand behind the roof liner and curiously it was very wet up there and I was concerned that the roof might be leaking especially at the point where the solar power comes through a hole in the roof.

In order to get a better appreciation of the issue I removed more trim and even got access behind the liner which curves down over the roof of the cab. What I found was that there is massive condensation at any place where the internal metal skin of the van roof is exposed. I find this very surprising as with the trim and liner in place there is nothing to indicate that this is occurring and to all intents and purposes the insulated liner is an air tight barrier between the inside of the van and the metal skin. There is no condensation whatsoever on the windscreen or any windows.

I have thought about leaving roof vents open to reduce condensation but I am concerned that open vents could be damaged by strong winds and in any case I don't expect much ventilation to get behind the roof liner to be effective. I don't think there is anything I can do about it.

How can we all sleep at night knowing what is happening hidden behind the insulation of our vans?

Mark

 

[DBK]

The trim can't be closely fitted or perhaps it's slightly porous? Our Murvi has a similar construction but I know we don't get condensation under the roof, it is too well fitted around the edges.

 

[Podney]

If there is no condensation anywhere else,does this indicate that there is water entering a nearby area that is then condensing as you have shown?
If it was condensation from the general humidity of the van,surely there would also be condensation on the windscreen.

 

[Mark and Mindy]

The trim can't be closely fitted or perhaps it's slightly porous? Our Murvi has a similar construction but I know we don't get condensation under the roof, it is too well fitted around the edges.

The Hymercar Ayers Rock trim and roof liner is well fitted and I would have never known that condensation is occurring if I hadn't removed so much liner as it is not apparent at the edges or the windows.

 

[Mark and Mindy]

If there is no condensation anywhere else,does this indicate that there is water entering a nearby area that is then condensing as you have shown?
If it was condensation from the general humidity of the van,surely there would also be condensation on the windscreen.

I first discovered condensation in the roof of the habitation area and I don't think it is a leak because there is also condensation above the cab area which is a different compartment.

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[Pausim]

It is better if insulation is bonded to a cold surface, even a miniscule gap is no barrier to moisture laden air. Loose insulation can even make matters worse because it stops the internal heat reaching the cold surface whilst other areas, such as a windscreen, will be getting some heat and air circulation. Moisture will condense on a cold surface and a thin metal roof soon cools in cold weather, probably quicker than glass does.

 

[TinaLes]

I See its a PVC, does it have a pop up top bed? Open all vents, let it breath a bit.
I would in the meantime expose as much of the roof as possible, wipe dry as much as you can, get a decent sized de-humidifier running for a few days, you could borrow one of ours if you were local enough to Surrey.
Have you been using the van recently?, as when it cools down, without the vents open condensation would naturally form on any cold surfaces, which would be the steel roof in your case.
I hope you get to the bottom of this shortly, I can see how it must be a worry for you.
Good luck.
LES

 

[Mikeco]

There should not be any exposed bare metal in a van conversion, it’s not rocket science to stick insulation on to it which will prevent condensation, also the ribs should be filled in as well.
Cannot understand why the professional converters don’t do it.

 

[TinaLes]

There should not be any exposed bare metal in a van conversion, it’s not rocket science to stick insulation on to it which will prevent condensation, also the ribs should be filled in as well.
Cannot understand why the professional converters don’t do it.

Good point, this must be a problem on every one they have built, the mind boggles.
I wonder if Hymer sub out their PVC conversions or re-badge maybe just to get into the ever growing PVC market, after all they have been in the game long enough to know better.
Other will know I am sure.
LES

 

[HandyAndy]

roof liner is not a vapour barrier.
Not enough insulation in that van AT ALL..
Was this a pro build or DIY?

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[Minxy]

roof liner is not a vapour barrier.
Not enough insulation in that van AT ALL..
Was this a pro build or DIY?

Hymer Aires Rock is a .... Hymer built PVC!

 

[HandyAndy]

Hymer Aires Rock is a .... Hymer built PVC!

Well that's positively shoddy then!

 

[Minxy]

Mark and Mindy the first thing I would do is contact your dealer and ask for their view on this 'water feature' and ask that it is immediately referred to Hymer as it is NOT in anyway 'fit for purpose'!

 

[Mikeco]

It took me 3 months to convert my van and the first month was spent on doing the insulation and just for interest I’m showing part of it below which is just the first layer over the filled in ribs.

 

[Campervan_man]

I have worked at a Hymer Dealership and a Malibu Dealership.
Malibu Panel Vans have 'foamy thin insulating black stuff' all over the bare metal structure.
Hymer Panel Van's seam a bit under insulated. The metal structure will be very cold this time of year and any warmth will quickly turn in to condensation as your pictures show.

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[Pausim]

3M Thinsulate has good thermal properties and also improves sound deadening. It is easy to install with a pva type glue and compresses to fit behind existing panels. You might need to avoid bulky or solid insulation because it could distort the panels.

https://www.marineindustrial.co.uk/files//7a9f0513-b570-4b7c-917a-a603011467f8/Thermal%20and%20Acoustic%20Insulation%20Catalogue%20(low%20res).pdf

I am wondering whether Hymer forgot to line your roof and walls, they clearly need it.

 

[Coolcats]

I want to install a 4G roof antenna for a MiFi which will involve making a hole in the roof of the van and so today I went about the potentially destructive task of removing cupboards and trim in order to get behind the roof liner. At one point I could get my hand behind the roof liner and curiously it was very wet up there and I was concerned that the roof might be leaking especially at the point where the solar power comes through a hole in the roof.

In order to get a better appreciation of the issue I removed more trim and even got access behind the liner which curves down over the roof of the cab. What I found was that there is massive condensation at any place where the internal metal skin of the van roof is exposed. I find this very surprising as with the trim and liner in place there is nothing to indicate that this is occurring and to all intents and purposes the insulated liner is an air tight barrier between the inside of the van and the metal skin. There is no condensation whatsoever on the windscreen or any windows.

I have thought about leaving roof vents open to reduce condensation but I am concerned that open vents could be damaged by strong winds and in any case I don't expect much ventilation to get behind the roof liner to be effective. I don't think there is anything I can do about it.

How can we all sleep at night knowing what is happening hidden behind the insulation of our vans?

View attachment 350724

View attachment 350725

Mark

Thanks for posting will have to investigate what is happening with ours, will be interesting to hear the outcome when Hymer have been contacted.

 

[Chris51]

It took me 3 months to convert my van and the first month was spent on doing the insulation and just for interest I’m showing part of it below which is just the first layer over the filled in ribs.View attachment 350743

Had mine sprayfoamed with MPI when I built it ..no damp etc.Sticking C's foam seems the best way for it.

 

[PhilandMena]

ventilation, ventilation, ventilation. Its the cold metal surface of the roof that is condensing moisture in the air. A small draught moving through the an will stop it dead. Try and crack open a window/vent as far apart as possible.

 

[Landy Andy]

Are you heating the inside of the van?

that will make it much worse

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[SpeedyDux]

roof liner is not a vapour barrier.
Not enough insulation in that van AT ALL..
Was this a pro build or DIY?

Absence of a vapour barrier is the fundamental problem.

Otherwise moisture in the warm air goes straight through the thin layer of insulation and condenses on the cold metal surface. It's a design issue.

 

[Mikeco]

ventilation, ventilation, ventilation. Its the cold metal surface of the roof that is condensing moisture in the air. A small draught moving through the an will stop it dead. Try and crack open a window/vent as far apart as possible.

Ventilation is good but will not stop condensation if the temperature outside the van is lower than inside it and it can reach uninsulated metal including ribs which form a cold bridge to the outside.

 

[Duckato]

The problem is very simple your van is not properly and adequately insulated and it won't be just in the area you have identified where the root cause is

Warm moist air is simply condensing on all and any exposed metal but could be getting there from various areas within the van.

I convert ex Ambulances as a hobby
you may find this playlist useful as an indication of how not to do it! one is of a customers Van and the other is what I found in my Crafter whilst gutting them

 

[CamperManLez]

To Mark, the 'insulation, second pic' is not attached/ bonded and sealed to the cold surface so any moisture will condense on the cold steel. You can do your own fix if you want by applying either YBS bubble insulation or closed cell foam, (Kiravans sell 7mm thickness and its a good product), the later is the better product but YBS is easy to fit around profiles However be aware that you should use a high temp spray adhesive (kiravans and others sell this) to ensure a long life bond. You have my sympathies on your findings, not nice to see having spent a lot of money. MHF Mikeko has shown a good job but manufacturers will not do things to this level as it takes too much time = cost.
There is a lot of 'myths' about 'Hymer' quality.

 

[CazPaul]

Very poor from Hymer, that's the problem with building a van, it's the bits you can't see that are the most important.

One of the reasons I was considering designing my own PVC van.

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[Jenka]

I can't believe a German manufacturer has done this as 90% on here rave about the quality! ??Only a little joke before you all start lol.

 

[Mr Rusty]

Had this issue on an Autosleeper PVC we bought new in 2005. I recall they changed the insulation process that year and instead of filling the void between the metal of the van and the lining decided to bond it to the roof liner itself. First really cold spell we used the van and the roof lining got wet with condensation dripping from the bare metal roof. Van went back to the factory and they reinsulated using their ‘old‘ method. Also had this happen in a coach built Hobby (van we bought after the Autosleeper). After picking up the van and spending a cold wet weekend in it we found water pooling in the cab overhead lockers. As it had rained heavy I thought the van was leaking but on reaching past the roof lining into the void between lining and glass fibre roof shell I could feel that it was full of condensation. This time van went back to dealer and Hobby authored them to remove the cupboards and lining and bond insulation to the inside of the fibre glass roof before putting lining back having made sure the void between lining and roof was also filled with rock wool. Never had another problem in the 4 years we kept the van. This is a case of manufacturers saving money.

 

[Steve Travelvan]

My 2014 Adria 6m PVC had water dripping down from above the windscreen on several occasions. The dealer couldn't find a water leak and said that it was condensation as the water hadn't stained the lining above the cab. Bare metal visible was damp behind ventilation grills. I took a cupboard off and found that the sticky foam insulation lining the van had gaps with the bare metal visible. The dealer sent my photos to Adria and they replied that this is how we build them! After a few years and more water dripping when the van was parked nose down I found small pieces of foam poking through the sealant behind the rear skylight where water collected when nose down. A good layer of Sikaflex behind the skylight seems to have cured that problem. I have also added extra insulation to cover the gaps in the original insulation on the areas I could get too. Adria build quality seems as poor as Hymers. A little extra care would ensure a proper insulation job!

 

[Campervan_man]

Hymer, Carado, Carthago, Malibu, Dethleffs, Burstners all great vans.
Lots of Classic Hymers on the road. I had a 1992 J reg Hymer and it was dry as a bone.

 

[RidersofRohan]

Presumably it’s not just PVC’s that might have this problem. The cab area of most Mhs will need a lot of work for a converter to do as the commercial van cabs will start life with minimal insulation.

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