A very compelling argument and perfect timing for me to stumble across it, cheers dude

2 years ago we converted a brand new Iveco Daily L4H3 which we now live in. That wasn't the plan originally but after two 90 day trips to Europe we hated being in a house. We stop warm air from touching cold metal by sticking foil bubble wrap to every inch of metal on the inside. We then insulated it with wool. 2 years on, a season sking in the alps and 2 summers in 30 degrees plus and we would recommend that method to anyone. We have no damp and the only condensation we get is on the windows of the cab.

Winter & Condensation. I was building my van in winter with a frost outside. Within 20 minutes of being inside, my van was like a rainforest, the condensation was just so very high. Time will tell whether you are correct, but after seeing my windscreen on the first winters morning of an overnight stay it really hit home the levels of condensation these vans suffer. I didn’t use a vapour barrier as such, I used high density foam wherever possible, diall insulation only in the difficult areas and sealed every hole I could find with aluminium tape. It doesn’t need to be air tight in my opinion, but you must stop the internal temperature meeting the external surface temperature.

Very valid points raised you have clearly thought long and hard on the subject nice to see you're not one of the sheep, haven't started my insulation yet you've given me a lot of food for thought 😰 hope everything goes well, crack on👍

This was very informative and helpful 👏 It provides a reasoned explanation for your decision and I would say that I agree with your evaluation!

I had some deadlocks fitted to my VW Crafter a few months ago. I mentioned I intended to do a camper conversion. One thing the fitter said was don't use expanding or non-expanding foam insulation. He said they often find pools of condensed water in areas where the foam hasn't filled. Makes sense to me. I would though use a mildly expanding foam in areas like inside the roof bars and other areas difficult to reach. I would make sure the foam has completely filled the cavity though. This is purely for the small ribs that strengthen the bodywork. I would recommend using a proper gun and choosing your foam carefully. There are different expansion rates etc. I would use the closed foam adhesive on the panels themselves over the sound deadening material like this video shows. As for a complete vapor barrier over the whole lot I personally think it would be beneficial.

Wonderful job, well done! Looking forward to it being finished. Will show it to my son, he has a Ducato.

Beautifully put. Totally agree. I used closed spray foam directly on to the panels (2 years ago) and so far no problems. No vapour barrier fitted. I’ve designed most of my wall panels to have plenty of ventilation, especially at the bottom, and they are all easily removed. Keep the van warm and ventilated when in use, and a dehumidifier in winter if possible

We came to the same decision to not put in a vapour barrier. We were on the fence for a while but the more we thought and researched about it, and worked in the van, the more we swayed against it. Like you still open minded and will keep some areas accessible to allow us to check every now and then how everything's looking, and chose hydrophobic insulation materials. We're going with the approach of dry heat and air flow to combat moisture and the assumption that warm air will inevitably come into contact with cold surfaces and condense. We've experienced water collect in one of the pillars through a small leak in the roof, and then seeing all the holes throughout, even the ends of the wire conduit and things like that. Tricky decision to make though as there are so many variables and you need time to tell if you have a problem or not. So we'll see! 🙂 Good luck with the rest of the build!

Well argued case for omitting a vapour barrier. A good layer of closed-cell foam against the van metal should prevent a good portion of condensation which together with ventilation of the other insulation plus good drainage will provide a very workable solution. These features are easier to achieve for the majority of builders than a vapour barrier which, as you point out, really does have to be near perfect to get the desired effect.

You are right. I've just bought an ex-Ambulance Service Command and Control vehicle to convert. All insulated etc, but no vapour barrier installed. It's 19 years old and the only bit of rust or rot was from a small leak in the back garage compartment where the extending NightScan lighting system was installed.

I like your style. Great build so far. Cheers 🍻

Good reasoning here in my mind. I think that good ventilation is the key and not a vapour barrier. I compare it to loft insulation that we had installed at home a few years ago where the installers covered the soffit vents and the roof sweated badly with water vapour soaking into the roof trusses. There was nowhere for the vapour to go. Luckily we found out in time, uncovered the vents and installed more to be sure and no issues since so I don’t think I will be installing a vapour barrier but will be making sure there is adequate ventilation just as there is in a caravan.

Very happy I found this video, thank you!

That's the right decision. If using in the winter get a dehumidifier.

I'm starting my third build and have never fitted a VB as in my mind airflow will keep the inner walls dry and fresh and remove mosture in the same way as the air bricks in older houses. Never had a damp problem in the previous two. Will now check your earlier videos as it's my first Relay.

Another thing to consider is the airflow from the cab heater, where the air gets in is obvious, the grille below the windscreen, but where does it get back out? On some vehicles there's an obvious vent at the back but that's by no means universal, my guess is that the manufacturer intends there to be an airflow through the walls & out the weep vents in the sills & various holes they've left around the underside.

Oooh controversial! It's your van, do it your way and stuff everyone else. Lovely job :-)

In one of the van conversion videos I watched, they were extremely thorough with vapour barrier and planning everything to minute details, yet still had external water leaks and other problems, so an external water leak is behind the barrier, then possibly trapped, I have gone for a hybrid approach, so I have access still. And like others have said if you ventilate the van and heat sensibly you should move moisture through

I noticed a professional van builder not using a vapor barrier not long ago so I asked him why? He said most professional builders won't fit one due to issues later on in the vans life

Thanks for a very good explanation regarding vapor barrier or not. We have come to the same conclusion as you, ventilate properly instead.

A Webssto or truma heater running at night needs the maxxfan opened slightly no matter how cold it is outside. Living in a van and allowing the heat to rise and escape slowly will make sure moisture escapes. Air conditioning while driving for 2hrs a week will remove any remaining moisture. Vapour barriers are more trouble than they’re worth.

Great subject, combating condensation in a van where people live full-time is a difficult subject to come to a conclusion about, .......on the whole I personally don`t believe in vapour barriers (except perhaps a dedicated shower area or flooring) because they create moisture traps behind many hidden areas (unless they are totally sealed everywhere), but I do believe in good loose insulation on top of or with what you have used (closed cell foam directly on the metal) and air gaps with good airflow & vent grids (even behind panelling) + heating to create a even ambient temperature inside a campervan (even in cold climates) - water will only pool if its got nowhere to go or drain = fugal growth (smells etc). Also i think people are too scared to not use a vapour barrier because they are concerned that their vans will rust from the inside, so is it possible to use a tanking solution (like they use in wetrooms in houses) to combat this on metal directly?

Great video . Ive been building most of my life and usually have been isulating wall and ceiling areas with some sort of air flow. I was also comtemplating using the súper quilt ( or space blanket as a lot of people refer to it )which I believe has the best insulating propertys available? and your video has sold it to me . Thank you sir 🙏

Hi there . Thank you for posting this video. Please can I ask you what you finished off the ceiling and in ? Looks like finished hard board. And what panelling is on the walls? Thanks

Agree 100% with every word, I am sure you are doing the right thing. Over the past year I must have viewed just about every van conversion video several times, and at last someone has put out a video addressing all the concerns that I have had. Brilliant. Thank you so much. By the way, if you examine the "professional" conversions or talk to any conversion company, I don't think you will find any vapour barriers being used. As in any inside space, good ventilation is the key. Now, where I have I heard that?

thats it i,m off to beachy head cant take anymore . lot of sense in what you say cheers

But what will happen to the 30 quarts of moisture that's gonna get into the one inch square hole anyway, regardless of whether there is a vapour barrier or not?

6:09 it is possible to stop PIR board squeaking, gluing it so it only touches one side is most obvious to me but there are other techniques.

Building an L4H3 Ducato down in Oz that will travel between hot dry air and hot wet air and like you reasoned out that breathability and ventilation are the key. Trying to keep water, and as you say - air, out of the intra impermeable barrier areas created by a vapour barrier would require an intensity and OCD like level of concentration beyond most of us. Many people have seen the vids and slapped the tin foil and bubblewrap staff everywhere, only time will tell. The positive aspect is that they are adventurers who have got off their backsides and had a go, kudos for that. Thanks for the great series and sharing your thoughts and ideas. God save the Queen.

I agree, occaisional summer use in the right conditions, the moisture will dry out. Ive watched loads of folk instal them, badly. Thats worse. The vapour will get in. It wont be able to dry out properly. In effect held in. It wont be able to dry out and air. I use mine occasionally spring summer autumn. Im going to dodo mat and carpet the top half, dodo, bottle fluff and panel the bottom. Shock horror, not doing under the floor, the wheel arches will be just timber covered. It's mint now, but it's my forever van. It'll need welding eventually.

Thank you very helpful

Very interesting food for thought

I am considering putting a one inch gap between the exterior walls and the interior walls without a vapor barrier. Inside this gap, I want to circulate dehymidified air and drain the water outside the vehicle. What do you think about this idea?

Hey, nice work! I've been watching your build for a bit now, and stealing ideas for myself ;) Question about the multifoil, how much of that stuff have you used for your ceiling and how have you attached it? Thanks

artic units basically had no insulation years ago, just a gap from trim to metal, crack a window open all was good seal it up and condensation was bad in winter, nightheater was dry air so wasnt a problem.

Hello, a friend of mine has been living in a step van for over 50 years, for real.

I have used a vapour barrier, didn’t find it a problem to seal it up effectively using foil tape, better to keep the moist air away from cold metal, especially with our high humidity levels here in the UK. I personally don’t believe a van could be ventilated sufficiently during the cold damp months to dry out any moisture that gets in to the wall space if there was no vapour barrier installed. Greg Virgo has an interesting video on the effectiveness of a vapour barrier on his channel.

I also have a L4H3 and been trying to work out a solution for having a rear passenger bench, two underslung CAK tanks, an underslung LPG tank, while also having a shower room with a fitted toilet. It seems this all may be possible after all from seeing your build.

I think you should just buy a submarine mate 😂 might be easier keeping the water out!ha … on a serious note, I’d be really interested to see an experiment of 2 vans, one with a barrier and one without and see if any differences after a few years.

Did you add any insulation into the channels down each side of the van, below floor level?

Hmm, interesting. So do most peoples vapour barriers just act as another insulation source then 🤔 What about if you run the air con whenever you're driving won't that dry it out enough. Great vid, 👍

Thanks for the video. I can’t find in detail how you did actually insulate the van; for example I’m using PIR board but won’t have a decent gap; I agree with your theory in principle but think it would need a cavity gap - for example in houses PIR board is installed with spacers. I’ve started with the foil taped PIR board method and have quickly realised it won’t be perfect despite best intentions so now feel stuck!

How have you found it now, a year on? Im in 2 minds now. I might do a vapour barrier to kind of funnel the vapour towards the roof fan but purposely leave ventilation holes in areas and allow for drainage

Here's a thought ( It's OK, I don't get a lot of these), you use a self adhesive insulation on the walls and ceiling of the van. Why not go the whole hog and use it on the inside of the wall panels and ceiling panels. Be they Solway, ply or any other hard material. You then have two layers of insulation with a decent air gap between. Also no rattling from loose insulation blocks or pooling of plastic bottle insulation. The van I plan isn't going to be used during winter, so how much insulation does it need? Would rather have the extra space, which is the real luxury. I'll get me coat...

Hey, thanks for your thoughts! Two years are gone now. Would you be so kind to do a follow-up video? Would like to know, you had any mold in your PET=insulation.

How have you found the use of superquilt? I use it in lofts for my day job on a regular basis and found it to be excellent so was stuggling to see why not many people seemed to use it on their van conversions. It seems the prefect solution. Thin, flexible and good thermal properties.

Can’t beat Superquilt, best type of insulation. Even though I’m talking from a building aspect

Always wondered why those conversion vans that transport elderly and such dont have any additional insulation other than oem .

Do you have a video on bed frame

Have you had any issues since the built was complete ?

5:19 that's Reflectix, several campervan builders use it.

It will find its way out. It will descend into the sill, and exit through the drainage holes.

So it's a year on and bearing in mind your low usage as you explained, what's the condition of your insulation now, doing things like this helps analyse and perfect

Iv purchased a 2012 Ducato Ambulance. They are partially insulated with 4 inches of Rockwool (glass fibre) spray glued to the walls. I took some of the trim panels off the outside of the van and the Rockwool was soaking, to the point it's causing rust. So it's a full rip out job. I have seen far to many van builds that stupidly used Rockwool as insulation and because it holds moisture it goes black and mouldy. So I think your correct. If your panelling/cladding the walls, that is a vapor barrier. Far better to use multiple layers of insulation, which stops the cold bridge from outside and that vastly reduces the amount of condensation forming on the cold metal surfaces. Your solway panels are already acting as a partial vapor barrier.

I find it a bit strange that people go to all this trouble to insulate but then you have the windows and the whole cab area open to the elements.It would be interesting to see a side by side comparison of 2 identical vans one insulated and one not.May keep the heat in but cool in summer?

Ill be doing a vapour barrier regardless. Seen way too many condensation problemsxas a builder

I've been working in my van for a month now & haven't done any insulation yet & i noticed that condensation only every forms on the roof panels, never anywhere else. It doesn't even condense on the roof ribs which many camper converters say is a thermal bridge & would therefore be just as cold as the outer skin. There is also a lot of condensation inside the ribs from the roof skin. I've a roof hatch fan which I open a little but haven't connected the electrics yet so I'm hoping that when the fan is trimming the condensation will stop. Ill also experiment with fitting PIR between the roof ribs to see if condensation still forms above it.

M8 absolutely brilliant your Wright about these supposedly full time vanners it's basically for the likes and to live on the subs there's a lot of gullible people out there that actually believe them big up your self love the build and the channel you and your family stay safe 👍 😀

Why did you use thick stud work for your walls? I screwed my ply to the ribs, so I have maximum width. I also didn't Insulate the floor, and it isn't cold. I used sound deadening, & 25mm insulation. I didn't use a vapour barrier, because it's bullshit.

There is clearly no perfect solution to avoiding condensation. In cold weather due to the temperature gradient between inside and outside, open cell or fibrous insulation will experience interstitial condensation where outwardly diffusing water vapour concentration reaches dewpoint and the insulation waterlogs. The point then in the rate of insulation breakdown is the rate of vapour migration, which is driven by indoor temperature, humidity and the vapour permeability of the internal wall and as mentioned, even small holes allow vapour to dramatically bypass the resistance of internal linings or vapour barriers. On balance I'd be looking at using closed cell insulation material that wherever exposed to vapour or contact with condensation / leaked water could not get saturated. There might then be good a case for having external vents, maybe with controllable shutters to allow ventilation in sunny conditions to improve drying out of cavities. I'm involved with a conversion in a habitation box fortunately with ready made 60mm foam sandwich walls and double glazed windows which should avoid the winter misery of a previous vehicle that would have been Rigsby's Rising Damp camper van of choice.

A man that speaks sense, exactly the same conclusion I came too

Very Interesting Video on the Vapour/ Moisture/ Air/ ⭐️⭐️⭐️⭐️⭐️⭐️

Well said, That makes complete sense, I don't insulate or vapour barrier never have done, never will do, never had a problem, its complete waste of time and money, ventilation is key. Use dry heat if using in winter, warm clothing and bedding. At the end of the day its a perforated tin box on wheels with windows and doors ITS NEVER GOING TO BE HOUSE! I would say some of the materials a lot of these youtubers are using is actually a potential health risk, trapping moister in and causing damp and fungal growth. I can un screw most of my cladding, take it off check it, replace it if needed and screw it back on again. Its fun, its safe, it saves money, and if your not a natural DIY person it saves a lot of time and hassle when building your van. Currently freezing my balls off in Snowdonia and living the dream 😂😂

Can you run a dehumidifier with your battery set up? No need for a vapour barrier then 👌🏻

Diy camper builders all seem to go down a black hole when it comes to insulation Inc you Let's put this into perspective No van or campervan on the planned is air tight Not one, if that was the case, People would die from a lack off oxygen. And with every justification to insulate. I can counter that argument because no one touches the cab area That's a 3rd off most vans If it was ubba critical to have to insulate or prevent heat loss, moisture etc etc at the back, why does that go out off the window when it comes to the cab Taking a realistic approach is something I've not seen by ANYONE

Sensible 👍👍

I rebuilt my van 6 years after it was built, and like all the other vans I’ve done, it didn’t have a vapour barrier and was bone dry

Convinced me. 👍🤣

Well, who am I to argue with you? You British people know your damp and mould right 😂

I also wonder if the van community are sheep, but about that expensive and heavy sound deadener. Its heavy its expensive and its hidden under numerous layers of insulation, boards and cabinetry. I am sure its pointless. Im also sure the commercially produced vans from the big boys like Hymer, Swift, Eldis do not use it (ive had a peak)

Agreed! re your Vapour Barrier assessment ...I wonder if a builder converted a van once and created a myth? For a vapour barrier to be effective the airtight seal needs to be absolute, which is impossible in a motor vehicle. All you can do is reduce the affect of any temperature difference between out and in by interrupting the thermal transfer (which you have done with the foam sheets on all large panels). This helps prevent condensation from forming on the bare inner skin in the first place. Then try to maintain airflow as much as possible to let it quickly dissipate if it does form. Great job on the build and love the sensible shortcuts you are taking with prefab panels etc, which also creates a great finish! I always pay myself a theoretical hourly rate then offset that against the extra cost of any prefab!

Never ever go to sleep in your camper without the windows open little say 3 mm ....absolutely no need for a vapour barrier impossible for it to work properly in a van !

Let's face it you wont be living In it full time In the winter anyway so no worries.

Installed a semi vapor barrier in my boxer van, there are gaps, and it is what it is, it is better than nothing, i doubt any van is truly vapor barrired. Also your solway panels are a non permeable barrier in them selves, !!!!!

How about the sound proof reasoning to add to the pros, and cons!,...Amazing how real sound proofing is achieved by doing this exact thing, with the same precision, sound waves, are like moisture waves, and any leaks are like a boat with holes, and no matter what material you use, Prepare to sink or swim!!...Can one noisy rig change your mind,!???...Maybe it's not about if, but about when!!!.....Noisy environments can make it unbearable, choose your poison!!!:

Wrong! Go watch Greg Virgo