Vapour barrier

[schubert]

Hi . When insulating my new van, IVECO DAILY panel van, I am going to use closed cell foam glued to the metal skin then a layer of Space blanket (WICKES) ,do I need a plastic sheet(Vapour barrier) on top off this before the ply linning ?.
We use our van all year in all weathers , going to the Alps in winter etc and plan to go to Norway in the winter months next year, so its important I get this right. Any ideas ?.
Thanks Schubert

 

[voyagerstan]

personaly i would'nt use a plastic one creates condensation i would use a tar paper one :idea-007: stan

 

[Byronic]

In practise no. However if moisture laden air from breathing cooking etc gets behind the wallboard then the dewpoint may occur in the body of the permeable insulation you are using, particularly if your outer closed cell insulation is of low resistance. it's known as interstitial condensation.
If your closed cell glued insulation has a reasonable resistance value then it's unlikely to occur. Best solution is to have all the insulation thickness of impermeable characteristics.

Personally I would put a vapour barrier on the permeable layer taping all joints and gaps, others may prefer not to seal, so that if dampness does occur, air can circulate and dry things out, you would probably need to use strategically placed vents, which then allows moisture laden air in if you don't close them at the salient times!

On 3 conversions I have used the vapour barrier option on full thickness closed cell insulation bonded to the body panels.

 

[hextal]

Condensation occurs when the moisture created by the people and activities occurring within the van cools on a colder surface. An impermeable membrane will stop the moisture in the air from soaking into the insulation. The type of membrane won't change the level if condensation that is affected by the level of moisture and level of insulation.

If the foam is closed cell it won't wick up the moisture. Foil is also impermeable so id say in this case youve already got it covered.