Prep work for fitting wooden 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...

 

[merl]

Think about it, what are you trying to achieve with the barrier and why?
ALL air has a moisture content right? It goes up and down with seasons/weather/activity in the van BUT there's always moisture in the air and unless it hit's something really cold it wont condense and cause a problem. You've coated the metal parts with foam insulation, this will prevent airborne moisture from condensing on the cold walls of the van and that's what's most important, and the vast majority of MHs and caravans out there will be way worse than yours WRT this.
Try as hard as you like you'll NEVER create a 100% water/airtight barrier behind the panelling, you'll always have tiny gaps that allow air exchange across the barrier, why would you want a perfect 100% seal anyway, because you'd prevent any moisture behind the barrier from drying out because it would be trapped there.
Panel it and get on with it, you'll be fine.

 

[n brown]

the ventilation sounds fine . but what is most important is that you seal the boards all round before fitting ,this will minimise shrinkage and warping . it's not unusual to see unsealed boards shrinking enough to pull the tongues out of the grooves . you can seal with oil ,water based varnish , emulsion etc

 

[trevskoda]

You dont use t & grove in a van as way to heavy, light ply and cover with stretch trim linning carpet, this is spray glued on, you can use plastic sheeting behind it if you wish.

 

[merl]

I've never weighed either but the thin softwood T&G is pretty light weight Trev, I don't think there'd be much in it weight wise especially after adding the covering weight.
I've fitted T&G in a number of bathroom jobs over the years and it can shrink across the width quite dramatically as it dries depending on how long it's been in stock at the shop, not sure 'sealing' would prevent that as suggested?? Don't see how it would TBH, but you've definitely got to let it dry out really well before painting because the paint bonds the tongues and grooves together and then the shrinkage doesn't get taken up evenly, rather about 4or 5 boards worth of contraction gets taken up every 4-5 boards and this leads to so much shrinkage at one point that the tongues pull out of the groove. Painting the boards prior to fitting with their final finish would eliminate this.

 

[n brown]

sealing stops moisture getting into the timber , but also seems to keep in whatever's there already . so it helps stabilise it . i can't recall how many T&G ceilings [and walls] i've fitted ,and i learnt this the hard way . never a problem on the dozens since
not a fan of carpeting walls and ceilings as it hangs on to cooking smells ,dust and sand , and it upsets me to see mrs b trying to Dyson the ceiling

 

[trevskoda]

I've never weighed either but the thin softwood T&G is pretty light weight Trev, I don't think there'd be much in it weight wise especially after adding the covering weight.
I've fitted T&G in a number of bathroom jobs over the years and it can shrink across the width quite dramatically as it dries depending on how long it's been in stock at the shop, not sure 'sealing' would prevent that as suggested?? Don't see how it would TBH, but you've definitely got to let it dry out really well before painting because the paint bonds the tongues and grooves together and then the shrinkage doesn't get taken up evenly, rather about 4or 5 boards worth of contraction gets taken up every 4-5 boards and this leads to so much shrinkage at one point that the tongues pull out of the groove. Painting the boards prior to fitting with their final finish would eliminate this.

Way to many fixing points for t&g also very thin linning ply is about 1/3 of the weight, just look at caravan construction.

 

[merl]

I'm not a fan of the look of either carpet or t&g tbh.but I guess it's the 2 easiest ways to getting a reasonable job done without too much faff
You can get self adhesive vinyl wrap in decent widths, I think I'd look into this over a very thin ply personally and use the same wrap on the internal partitions etc.

 

[trevskoda]

I'm not a fan of the look of either carpet or t&g tbh.but I guess it's the 2 easiest ways to getting a reasonable job done without too much faff
You can get self adhesive vinyl wrap in decent widths, I think I'd look into this over a very thin ply personally and use the same wrap on the internal partitions etc.

Yes seen it done, nice and easy to clean, as you see parts of my van has just paint onaround the kitchen toilet and enterance

 

[Millie Master]

I had the entire interior of my Renault Master closed cell spray foam lined 8 years ago, it was one of the best decisions I made!

After smoothing back the oversprayed foam, I then bonded thin plywood pads to numerous areas and then, when I was 100% sure that all the pads and ribs were at the same level, I then bonded the 3mm Morland vinyl faced plywood to the ceiling and wall pads using Stixall on those areas of the walls that were being covered this way. The other areas were covered in thin lightweight oak faced ply which was then satin varnished.

None of the walls or ceiling has ever shown any signs of damp during our 8 years of touring throughout the UK & Europe in temperatures as high as + 42C and as low as - 17C.

 

[guerdeval]

I looked at a ducato van before purchasing mine which was all ply interior and the seller very reluctantly weighed it for me, 3420kg, needless to say I walked away.

 

[Pudsey Bear]

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...

Closed cell spray foam is itself a vapour barrier, clue in the name

 

[trevskoda]

I looked at a ducato van before purchasing mine which was all ply interior and the seller very reluctantly weighed it for me, 3420kg, needless to say I walked away.

Prob thick stuff and to heavy.

 

[Pudsey Bear]

You dont use t & grove in a van as way to heavy, light ply and cover with stretch trim linning carpet, this is spray glued on, you can use plastic sheeting behind it if you wish.View attachment 120634View attachment 120636

You can get what is called Marchwood Trev about 6mm thick, weight could be an issue still.

 

[Pudsey Bear]

I've never weighed either but the thin softwood T&G is pretty light weight Trev, I don't think there'd be much in it weight wise especially after adding the covering weight.
I've fitted T&G in a number of bathroom jobs over the years and it can shrink across the width quite dramatically as it dries depending on how long it's been in stock at the shop, not sure 'sealing' would prevent that as suggested?? Don't see how it would TBH, but you've definitely got to let it dry out really well before painting because the paint bonds the tongues and grooves together and then the shrinkage doesn't get taken up evenly, rather about 4or 5 boards worth of contraction gets taken up every 4-5 boards and this leads to so much shrinkage at one point that the tongues pull out of the groove. Painting the boards prior to fitting with their final finish would eliminate this.

If you varnish the whole surface back, sides and the cut ends any moisture should stay in the wood Merl so there shouldn't be any real shrinkage.

 

[Glandwr]

If you are concerned you can get very sophisticated vapour barriers from builder's merchants these days especially ordering on line. Totally waterproof, stuff that is fully breathable and stuff that will act as a moisture barrier oneway only.

 

[Pudsey Bear]

Visqueen or decorators sheet would do.

 

[trevskoda]

There is also a man man made wood which is used in boat building, finished and ready to go, big problem is how do you hide the screws or like mine the rivets, hence i covered in lining material.

 

[Rob H]

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...

Hi Poindexter, My VW T5 camper retirement self build, I used M6 rivnuts throughout to secure all panels and units, insulation is Superfoil, located agains the outer skins and hollow body frames that are (sprayed inside and with wayoyle) with mushroom shaped nylon supports bonded to the outer skin, a heavy polythene vapour barrier throught, and internal ply panels all roller varnished before carpeting, both sides and edges ( you mention using tongue and groove, its heavy and less moisture stable than WBP ply ) secured using slightly enlarged original fixing holes to take M6 Rivnuts and plastic capped M6 fixing screws. My job before retirement involved R & D designing layouts for work vans, scrutinising official work vans that had been involved in road traffic accidents to improve specifications, generally internal woodwork fittings would be detached and reduced to matchwood, reason was, metal vehicle bodywork involved in crash, ripples and flexes and deforms while internal often rigid wooden fit out, if only bonded in place doesnt, being more rigid, it detaches and keeps traveling .. ventilation v insulation in steel vans is a challenge, moisture in vans tending to form high, and trickle down and settle low in the bodywork. Good luck with your build, well worth the effort, and design is half the fun.

 

[Pudsey Bear]

I looked at all the standard insulations and 100mm air gap was a must, except spray foam.