The insulation of a camper van is one of those things you can't see once the build is finished, but that you feel every night. Doing it well is the difference between sleeping comfortably in a mountain area and spending the night shivering or, in summer, inside an oven. And because it ends up buried under walls and furniture, redoing it later is very costly. So it's worth understanding before you start.
Why insulating matters so much
Insulation does two jobs: slowing the passage of heat (so it doesn't escape in winter or get in during summer) and helping to control condensation, the damp that forms when warm interior air touches cold metal. An uninsulated van is basically a tin can: it heats up and cools down at full speed.
Which material to choose
There's no single perfect material; the usual approach is to combine several:
- Elastomeric foams such as Kaiflex or Armaflex: widely used on walls and roof. They're flexible, they follow the curves and they act as a vapour retarder in themselves. One of the most recommended options for its balance of insulation and ease of fitting.
- Reflective multilayer insulation: thin, useful combined with others and for the floor.
- Sheep's wool or natural materials: they behave well with moisture, although they're bulkier.
Avoid filling cavities with materials that absorb and hold water uncontrolled, because moisture trapped against the metal is what causes rust and bad smells over time.
The vapour barrier: the point that raises the most questions
A vapour barrier is a layer that stops water vapour from inside passing through the insulation and condensing against the cold metal. It always goes on the warm side of the insulation, that is, towards the interior of the van. If you use Armaflex-type foams with well-sealed joints, the material itself largely does that job. The key is continuity: a barrier with holes in it isn't much use.
Watch out for thermal bridges
A thermal bridge is a point where the cold "jumps" the insulation: typically the metal ribs of the bodywork, which stay in direct contact between outside and inside. You can't always eliminate them, but it's worth reducing them by covering them as far as possible. They're also the points where condensation appears first.
Don't forget the floor or the windows
The floor is insulated too, before you fit the panel you'll walk on. And the windows are a major heat-loss point: good thermal blinds or made-to-measure insulating covers for the glass make an enormous difference on cold nights, and they're removable.
Insulating and ventilating: two sides of the same coin
Here's the paradox that surprises many people: the better you insulate and the more airtight the van becomes, the more important ventilating is. Otherwise the moisture you generate by breathing and cooking stays inside and condenses. Insulation and ventilation go together; we cover this in condensation in the camper.
In short
Insulating well means choosing a good material (Armaflex-type foams are a safe bet), fitting the vapour barrier towards the interior, reducing thermal bridges and not forgetting the floor and the windows. The step you can take today: before buying material, measure the surfaces properly and decide your vapour barrier strategy; improvising that halfway through the build is what causes damp problems later. And remember: the more insulation, the more ventilation you need. If you're going for the full build, also look at the best vans to convert.
