Campervan Vapour Barrier ? Yes Or No
- Thread starter Oldrat
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Thanks Oldrat, hope for the future then.
Sorry for the late reply Oldrat, a lot of the negative points on vapour barriers have been covered since i posted, so i don't need to go through them again.
We just completed a 3 +month long trip and didn't have a issue, granted we used the maxxfan overnight to ventilate, even with the diesel heater running
the key is to ventilate the van, as it reduces the moisture buildup within a confined space.
We just completed a 3 +month long trip and didn't have a issue, granted we used the maxxfan overnight to ventilate, even with the diesel heater running
the key is to ventilate the van, as it reduces the moisture buildup within a confined space.
As a residential Surveyor, I recommend balancing heating and ventilation....it’s not healthy for building nor occupants not to ventilate. Same for vans I assume.
You may be surprised how many modern double glazed windows clearly haven’t been opened for a considerable time....with trickle vents also shut.
You may be surprised how many modern double glazed windows clearly haven’t been opened for a considerable time....with trickle vents also shut.
Thanks for the responses to date guys, I really appreciate your input and helping my pea brain understand the processes. 
What’s bugging me is that even with ventilation, I would expect some condensation to form on cold surfaces anyway especially when cooking/ boiling water etc.
Unless of course, you are prepared to have a gale blowing and windows and doors all open?? Is that a reasonable assumption?
I understand that ventilation will reduce the moisture content in the air. I presume that it does that by removing a large chunk of air and dumping it outside rather than extricating the moisture from the air in the entire van?
In which case ventilation reduces moisture content not eliminates it.
I also have the view through air between the internal panels and the metal van exterior does not circulate, because of the insulation - that’s how it works.
So looking at this gap between the two ...
if it is sealed with a moisture barrier, it’ll only have the very slight amount of moisture present in the ambient atmosphere at the time of building.
If not sealed then it would slowly over time increase the amount of moisture firstly permeating from the van interior (and secondly from condensation - have I got that right??)
Am I making too much of all this??
It’s driving me nuts .
What’s bugging me is that even with ventilation, I would expect some condensation to form on cold surfaces anyway especially when cooking/ boiling water etc.
Unless of course, you are prepared to have a gale blowing and windows and doors all open?? Is that a reasonable assumption?
I understand that ventilation will reduce the moisture content in the air. I presume that it does that by removing a large chunk of air and dumping it outside rather than extricating the moisture from the air in the entire van?
In which case ventilation reduces moisture content not eliminates it.
I also have the view through air between the internal panels and the metal van exterior does not circulate, because of the insulation - that’s how it works.
So looking at this gap between the two ...
if it is sealed with a moisture barrier, it’ll only have the very slight amount of moisture present in the ambient atmosphere at the time of building.
If not sealed then it would slowly over time increase the amount of moisture firstly permeating from the van interior (and secondly from condensation - have I got that right??)
Am I making too much of all this??
It’s driving me nuts .
We got loads of condensation in our van whilst sleeping in it for 2 nights this weekend. But, we then did a 3 hour drive home with the aircon on, which will have stripped out virtually all of the condensation in it. If we hadn't done that drive, then I might have been concerned. I think this is where you can't compare a house with a camper van.
How many campervans have rotted from the inside out ?
Pete
How many campervans have rotted from the inside out ?
Pete
Thank you, that nicely demonstrates my point, all that vapour permeating into the cavities and condensing on the metal surfaces unseen.
And even with your drive home with air con on and windows ajar, I can’t see how that would remove any condensation formed behind the panels.
And even with your drive home with air con on and windows ajar, I can’t see how that would remove any condensation formed behind the panels.
Uninsulated T3s are noted for rotting from the inside out! Extremely common. I can't see any reason why the T6 will not be the same over the same time frame of 25 - 30 years.
The warmer the air, the more moisture it can hold, and logically the colder the surface it hits, the more condensation....therefore ventilation essential. It’s easy to see that if serious condensation can form on the inside of metal panels, it can run down and pool on the floor and inevitably corrode metalwork, and also cause problems for the lining, compounded if held in an insulation material. Not an easy thing to combat effectively in a van.
Insulating directly onto the internal surface of an external panel has to be ideal to reduce the chance of condensation forming there and running into the bottom of the vehicle and pooling.
In house flat roofs the the tendency these days is to apply a thick layer of insulation to the outside surface of the roof with no insulation between the back of the plasterboard ceiling and underside of the roof sheeting ply... obviously at some point this will be adopted by the campervan community with T6 wide body kits...
In house flat roofs the the tendency these days is to apply a thick layer of insulation to the outside surface of the roof with no insulation between the back of the plasterboard ceiling and underside of the roof sheeting ply... obviously at some point this will be adopted by the campervan community with T6 wide body kits...
I have floor prepped with ply.
Dodo hex between the prep.
Then sealed taped any gaps to the floor prep.
A layer of radiator reflector foam stuff,
Then 12mm ply.
The sides are dodo hex in the big areas to lower noise
Then I have stuffed any gaps with Dacron.
The big areas I will use bubble foil.
The metal surfaces then carpeted
The sides then 6mm ply lined and carpetted.
creating a sealed vapor barrier is almost impossible anyway to be honest. There is so many holes in the body. I always put wet gear in my work van, I have stuffed dacron in numerous areas and those areas I have not put dacron, you get condensation on the metal on the inside.
Key is not to stuff the darcon super tight, keep it light so there is an air differential temperature. The more layers between in and out the better but its just not possible to do in a van. Impossible to stop if its 0.1C outside and 26C inside and the only thing seperating it is 10cm.
Dodo hex between the prep.
Then sealed taped any gaps to the floor prep.
A layer of radiator reflector foam stuff,
Then 12mm ply.
The sides are dodo hex in the big areas to lower noise
Then I have stuffed any gaps with Dacron.
The big areas I will use bubble foil.
The metal surfaces then carpeted
The sides then 6mm ply lined and carpetted.
creating a sealed vapor barrier is almost impossible anyway to be honest. There is so many holes in the body. I always put wet gear in my work van, I have stuffed dacron in numerous areas and those areas I have not put dacron, you get condensation on the metal on the inside.
Key is not to stuff the darcon super tight, keep it light so there is an air differential temperature. The more layers between in and out the better but its just not possible to do in a van. Impossible to stop if its 0.1C outside and 26C inside and the only thing seperating it is 10cm.
I love this post, as I read one entry to the next I go from 'yep, put the vapour barrier in' to 'naaa, it'll be fine with some good ventilation'.
Gregs video's are very thorough, he does insulate and then add the vapour barrier. This is key, and means that in those areas there's no 'cold' surface for the moisture in the air to condense.
However, as many have noted; it's practically impossible to get to everywhere in a T6. If I was planning month long trips then I might consider it, however it'll be two weeks at best and if the weather's that cold where condensation is forming my wife will make me driver further South
Gregs video's are very thorough, he does insulate and then add the vapour barrier. This is key, and means that in those areas there's no 'cold' surface for the moisture in the air to condense.
However, as many have noted; it's practically impossible to get to everywhere in a T6. If I was planning month long trips then I might consider it, however it'll be two weeks at best and if the weather's that cold where condensation is forming my wife will make me driver further South
Interested to know, now that years have passed and assuming you decided not to vapour barrier, was it the right choice? I’m in the same mindset as you were!I love this post, as I read one entry to the next I go from 'yep, put the vapour barrier in' to 'naaa, it'll be fine with some good ventilation'.
Gregs video's are very thorough, he does insulate and then add the vapour barrier. This is key, and means that in those areas there's no 'cold' surface for the moisture in the air to condense.
However, as many have noted; it's practically impossible to get to everywhere in a T6. If I was planning month long trips then I might consider it, however it'll be two weeks at best and if the weather's that cold where condensation is forming my wife will make me driver further South
