Insulation newbie question

[SpaceDawggy]

Hi,

I've recently got my T25 back from the body shop where all the rusty panels were replaced and I had the lower half of my van resprayed.  Additionally all new window rubbers were fitted.

Yesterday I stripped out all the interior carpet old cavity insulation (looked like rockwoll) on panel where I had a repair done above the insulation was moist.

I'm now in the process of removing the left over glue and completing a general tidy up including removing all the dangerous wiring in the van and planning out the replacement wiring which will go in the panel spaces where possible.

Next task will be to fill the cavities filled back up with insulation and I have a couple of questions.

On the back of the mew panels I'm going to put 2mm dodo matting to sound proof them.  Over these and over the old deadening I was going to put recycled bottle insulation like Thermafleece which is non moisture absorbing.

The question I have is after this do I need to put a vapour barrier over the panel before the new door cards?  Or should I leave it as is to breath?

Is there any point in putting vents at the top and bottom of the panels to let them breathe?

After the door cards go on I'll re-carpet the interior then kit it out again.

Lastly and a bit off topic, I'm going to need a roof vent, so I wondered if anyone had a recommendation for a hard top, I'm keeping the original roof.

[keynsham1]

I am just refitting my van and I am not putting insulation into it. I have also only used sound deadening sparingly, more to just dampen vibration rather than stop noise. I never considered the inside of my van as being very noisey and I was put off the Dodo mat and equivalent because of the weight! It is increadibly heavy and if you cover everything it would be a massive extra weight to carry around. As the van is full of carpet, beds, seats, cupboards etc, it is pretty sound deadened anyway!!

I am also no putting insulation in for the simple reason that all insulation will hold on to moisture and eventually cause corrosion. Sleeping in a van causes a lot of moisture just from your breath and insulation will hold on to that. I only stay in my van in the summer though so it isn't really needed and was never fitted when it was new. Also I have a heater if it gets too cold!!

[clift_d]

You’ll want to try and fit some kind of vapour barrier somewhere inside of your insulation, ideally just below the lining cards. This is to stop any moisture vapour in the air inside your van getting into the panels where it can condense and cause corrosion. You’ll need to try to get a good seal at any edges, and between sheets, so that it is as airtight as possible. I’d also suggest that this is something you’d probably want to do in an un-insulated van, for the same reasons.

[syncroandy]

I would suggest avoiding any approach to insulation where the spaces between the outer panels and inner trim are just filled with loose material. Regardless of what its made from, there is still a risk it will tend to absorb and trap moisture, and will reduce air circulation so moisture will tend to build-up and fester, instead of being able to vent away and evaporate.

When I did my kombi, I used ~15mm closed-cell PU foam sheet (from Reimo), glued to the inside surface of the outer skins. This was done with the interior panels and headlining removed. Where there was space, I used two layers, giving ~30mm. This acts both as sound-deadening and thermal insulation. The foam was cut with a gap around the edges to keep it from resting on any spot-welded seams.

Whilst I agree the biggest source of moisture inside a camper is condensation, I think trying to fit vapour-barriers could be counterproductive and just end up trapping moisture if not done very carefully. In my kombi, its just the vinyl-covered interior panels that keep inside air away from the insulation.

 

[Smiffo]

I am just refitting my van and I am not putting insulation into it. I have also only used sound deadening sparingly, more to just dampen vibration rather than stop noise. I never considered the inside of my van as being very noisey and I was put off the Dodo mat and equivalent because of the weight! It is increadibly heavy and if you cover everything it would be a massive extra weight to carry around. As the van is full of carpet, beds, seats, cupboards etc, it is pretty sound deadened anyway!!

I am also no putting insulation in for the simple reason that all insulation will hold on to moisture and eventually cause corrosion. Sleeping in a van causes a lot of moisture just from your breath and insulation will hold on to that. I only stay in my van in the summer though so it isn't really needed and was never fitted when it was new. Also I have a heater if it gets too cold!!

The bloke doing my van advised the same. Sparing use of sound deadening in a few key areas, and not much else.
 

[sweetaswesty]

I’m refitting the interior of our hightop Westfalia and I’m replacing the old fibreglass insulation with the recycled plastic bottle type that is available from Dodo but also B&Q and just about everywhere else. I’ve used Dodomat type sound deadening stuff and also closed cell insulation on the panels also.
I don’t think the new insulation has the same ability to soak up gallons of water that the old stuff had but anyway in our van it wasn’t just the insulation holding on to condensation that was causing the rot but the way the condensation collected on otherwise unprotected surfaces. So I’ve thoroughly rustproofed those panels from the inside out also.
Our van was rust proofed fairly thoroughly from new by VW to protect it from the bottom up and for a thirty year old vehicle it was in pretty good condition tbf but nothing at all was done to protect it from the top down corrosion caused by its use as a camper. Yet even so it took many years for it to begin to rust through - in all the usual places.
So with insulation that doesn’t retain moisture to the same extent, plus rustproofing I don’t see why it won’t last longer than I’m going to last myself.
Also do non-insulated vans actually suffer from less seam rash etc., etc., than insulated vans?
I’ve toyed with the idea of using plastic sheeting to provide a moisture barrier but practically that seems impossible to achieve to me.
That’s my reasoning anyway fwiw.

[Stesaw]

When I redid my van last year used the dodomat sound deadening type sheets and cut them into suitable shapes to line the panel. Then used waxoyl on the cavities and floor underneath the window where water was getting which blew out my sill. After that used the recycled plastic bottle insulation in the cavities, where the bigger panels were I used a bit of trim fix spray glue to hold it in place.
As for a barrier I used some clear plastic sheet i had lying around and sprayed trimfix around the holes then just put the plastic over it and trimmed it with a knife.

Make sure you route all your leisure cables first though through some conduit