Vapour Barrier in a Van - I can Prove they Work.

I carry out a real test to show you that a vapour barrier does work and they can completely prevent the formation of condensation.

There are so many different opinions about vapour barriers in steel vans and nobody is proving their point, so I will prove to you that they do work.

The vapour barrier prevents moist air from coming into contact with cold surfaces and totally eradicates any condensation from forming in the first place. If the air cannot get to the cold metal then it cannot condense into water.

It is really easy to make a sealed barrier with foil bubble wrap and foil tape, just make sure to seal all the edges, joints and tape over any holes and service entry points.

There are many more useful videos like this in our full van build series

I'm an engineer so I like to deal with facts and science, not speculation and conjecture. I will only give you sound advice so please do subscribe to the channel and hit the bell notification. its a great way of saying thanks and its free.

Thank you very much for watching
Greg Virgoe
Eng Tech LCIBSE
Mechanical Engineer

#vapourbarrier #convertavan #preventcondensation

[jazzz]

A great practical demo on how it works! Genius. Thank you Greg! When I did my insulation I got half the van done with VB then winter came. Half my van was dripping where there was no VB, and the other half even though not sealed at edges was bone dry when I cut into it to check. So doesn’t even have to be 100% sealed to be massively effective. If the air doesn’t move through that gap it can’t carry moisture into it. Obv being sealed helps guarantee this. Front half of van started getting mould spots where water droplets kept collecting on top of PIR boards in ceiling. Vapour barrier for the win! Can’t cheat physics!

[rbrown]

Nice demo but there is a problem !

In theory in a tiny test where you can actually fully seal off the area, yes it works.

Vans are not fully sealed nor are they meant to be. Manufacturers have many drain holes, plugs, plastic trim attachments that come all way through into the inside of the van cavities. Thats why vans are designed to drain. Then we go and try to fully seal them up.

I do partially agree that adding multiple layers of good insulation and having partial sealed barriers on large wall and roof areas is a good idea.

BUT you simply can't full seal up all voids and all areas. So what happens when you try ? You end up sealing in any damp and wet that gets behind your vapour barrier, and it will.

Best idea is to use some form of final sheet layer of insulation (vapour barrier) to all large surfaces areas, this prevents "most" of your living space warm moist air hitting the walls BUT then add good ventilation so the easiest path for all that moisture is your roof fans, open windows etc.

All the areas you can't fully seal, allow the cavities to still breath.

On our van I did 90% seal up with a final layer of sheet insulation behind roof and wall panels. But at the edges where roof and ceiling join, at the lower areas especially at the back of van, the cavities can still breath to dry out if need be.

our 2 Maxx Air Fans are either open, or open and running pretty much 24/7. IN below zero in winter if were skiing the roof fans are open and Diesel air heater running to flush moisture and dry the air out.

A year later and I have pulled wall and ceiling panels and zero condensation issues. Day to day inside the van we never get condensation, just a little on the inside of the windscreen sometimes.

But as far as trying to full seal the van with a vapour barrier, from all the research I've seen vans aren't designed nor should they be full sealed up, vans are nor designed by manufacturers to be fully water proof and fully sealed up behind all the cavity spaces. Thats why there are drain holes all along the van sills.

[maxv]

I was watching a video on this subject from a guy who builds campervans for a living. He didn't put a vapor barrier on. I questioned this. He said most professional van builders don't as it causes more issues later on down the vans life.

[PixelShade]

Greg, you are an absolute treasure for the RV- and Vanlife community! :D Having videos like this is key for people to understand how these things work.

[campervibe]

100% agree with you on vapour barriers. Great vid 👍

[leebrown]

Smug grinning from me as I followed his advice. I can't tell you how many videos I've watched that said you don't need it.
Thank you Greg 👍

[peterbrockman]

I live in Tasmania and when I commenced my van build I had the luxury of watching your van build videos Greg. Hence my Sprinter has a complete vapour barrier and is well insulated. This demo video just impresses how vital those two components are when well fitted. Thanks mate. 👍

[AndyMiles-quew]

well done that man, you have done me a 100 % big favour. I have now decided how to insulate and vapour seal my van. Thank you.

[fboest]

Those kind of proof videos are absolutely brilliant

[boris_the_crafter]

I'm all for vapour barrier and have installed it, the experiment has proved the need for insulation. It would have been interesting to see a 1/3 of the bucket with just insulations 1/3 with vapour barrier 1/3 bare metal.
Cheers for the video anyway 👍

[LindzandLife]

Thank you Greg this is the way I've done my insulation on my build and so much rubbish about the vapour barrier. I'm about to start electrics and your videos are a blessing 🙌

[jonnypickett]

Nice one Greg. I have followed your advice on 3 van builds after seeing that you obviously know your onions.. I would be interested in seeing the test again using insulation but no vapour barrier as I know many builders put in insulation with no barrier..

[stephenhall]

Hi Greg, it was great to finally chat to you in person after following you for nearly 4 years.
Hope you had a great Camp Quirky. You will need a rest after meeting so many people.
Regards,
Steve.

[CLdriver]

Well done Greg. I’m going to share this video with my van builder friends!
Edit: There’s also the effect of increased relative humidity due to cooking, heating and breathing. Good reason for proper ventilation as well.
Thanks again for another great van build video. IMHO, you’re one of the best on YT!

[eddvanlife]

The Legend Of Virgoe continues. Thanx for clever chemistry lab demo.

[mablethebus]

Great video Greg. And great to meet you yesterday and took the time for a chat. 👍

[lud]

Hi Greg thanks for another great video👍. Just watching a new channel called Ame in a van and she talks about this guy who is an absolute legend who she watched whilst building her van. That guy is you.👍

[janc]

I've been trying to get this question answered for ages!!! Thank you!

[BigPubez]

Thank you for helping me to FINALLY understand vapor barriers!

[markthompson]

Best video on YouTube on this vital subject....Fabulous