Prep work before fitting wood cladding

[poindexter]

Hey Forum, I am at a critical stage of my campervan conversion project and looking for some advice here please.

I have insulated with spray foam and now would like to proceed with cladding the walls with tongue and groove wooden cladding. I have installed the wooden framework to attach the cladding to but am a little concerned about moisture.

It would be very difficult to create a moisture barrier with the tongue and groove. It is definitely what I want however.

Just looking for general advice really on what I should do in preparation for fitting the cladding? I did think that I could put in a 3mm ply underlay and seal it around the edges but that would be a fair bit of extra work, cost and weight on a Transit Jumbo.

The van is well ventilated with two floor vents, a spinning vent on top, two skylights and two roof vents.

Should my ventilation be good enough that I don't need to worry so much about airborne moisture or should I do some extra prep work? If so are there any good suggestions that are faster, cheaper and lighter than what I had in mind?

Appreciate your responses...

[bortaf]

if it's closed cell foam then it's technicly a vapour barrier itself if it's the normal builder stuff in a can it's probably open cell so not really a sealed layer ?
i've just used polythene vapour control barrier from screwfix or wicks ect, you can use silver backed bubble wrap but it's a waste of money IMHO ? TBH there's 2 ways of tackling it, let it breath or seal it, if you don't use a barrier make sure it's vented top and bottom of the wall
AS you say lots of ventilation is more important but it never hurts to go the belt and braces route

[dumper]

On all the camper’s I’ve built never used a vapour barrier all I’ve done is waxoil the body panels then used the recycled plastic bottle insulation foam and with lined ply wood with carpet to finish.I built a mk3 this way and later upgraded to a mk5 transferring the conversion into it and the insulation was as goofy as the day I fitted it .