Choosing Low Impact Campervan Insulation

low impact van insulation

Driven by a desperate need for the family and I to have a break in the country, I’m converting my old Sprinter van into a camper with insulation being this week’s task.  So I thought I would share my thoughts about which materials to use and why I made the choices I did.

Bear in mind that this particular project is an organic process aiming to make use of things I can acquire cheaply and upcycle where possible which means I’m not sure what is going where until I find it! This also makes future remodelling inevitable.   I’m also on a very tight budget.
There are two different fundamental decisions when insulating a campervan; do you use a moisture barrier or not? When the van is in use moisture is generated by, for example, cooking or sleeping and it can be exacerbated by extreme temperature differences between the inside and outside of the van.  That moisture must go somewhere and if not controlled could cause damage. To overcome this problem the van needs some form of ventilation, a skylight is a good solution or an extractor fan in the cooking area can be a good idea.
How this affects what insulation is used depends on whether you choose to have a barrier to keep the moisture away from the insulation or not. I decided against a moisture barrier for a few reasons. I could see that  trapping moisture in the van somewhere I couldn’t access  could cause problems in the future. I also want to be able to gain access to the various cables that might run behind the walls or install vents at a later stage and a  moisture barrier would be in the way and easily damaged during this process. What are the choices?


Pros- cheap, readily available in a variety of sizes/density, fairly easy to cut and shape

Cons – It can hold water so a vapour barrier is a necessity or it will rot, it can break down and drop behind the walls with all the vibration and end up leaving the top of the walls without insulation.  There is also the prospect of itchy mask hell (it really has to be sealed in to avoid fibres being released into the living space and causing problems, too.)


Pros – cheap, readily available, easy to shape odd cavities, resistant to moisture

Cons – it can crumble easily with vibration and end up in piles at the bottom of the walls, I was worried that it would be easy to create a really squeaky van and the thought of driving thousands of miles accompanied by polystyrene squeaks was too awful to contemplate.

Spray foam

Pros- this really appeals to the geek in me, it creates a sealed layer and performs the job of a vapour barrier.  It does an excellent job of deadening the panels and makes the van very quiet.  As it’s applied directly to the metal of the van, all your utilities can run behind walls and thus  be insulated (good for water pipes) but also avoid problems with being buried in insulation (bad for possibly overheating electric wires), it’s easy to shape once done.

Cons- Cost! It’s not a cheap thing to get done, there are kits available to do it yourself but they aren’t cheap either and it looks like a messy business.  There is also a possibility with spray foam that you can create moisture traps beneath the foam and hidden rust can set in that you have no idea about until it’s a significant problem.

Sheep’s wool

Pros- the environmental impact is low, it is an excellent insulator, it is resistant to rot from moisture, it’s breathable, it’s nice to work with,

Cons- the cost, it’s quite expensive and the numbers add up fast with a decent size van, it’s roughly twice the cost of polyester


Pros- this stuff is made from recycled bottles so it scores well for sustainability, it’s very pleasant to handle no itching or masks required, it is impervious to moisture; so won’t rot and it will take a long time before it starts degrading significantly enough to lose its integrity.  It’s also reasonably priced and not too hard to source (though I had to buy from two different suppliers to get the different thicknesses I wanted).

Cons- It’s not the cheapest option.  It’s a bit tough to cut; scissors worked for me and the thicker of the two types I got tore easily in one direction but not the other, the thinner type needed cutting both directions

Kingspan and similar

Pros- good moisture resistance, easy to work – can be carved with a sharp knife, moderately priced, not toxic to work on – no itches and dust and is robust – it doesn’t look to me as if it will disintegrate in a hurry

Cons- it’s tricky to shape into curved van shapes (I used this in some areas of the first van I converted and it was great in the large cavities lower in the walls; but as the spaces grew tighter and curves more extreme I found the polyester insulation much easier and faster to do. It’s hard to get into gaps behind structural members and, for this reason,  I always felt that there were a lot of gaps in the insulation of that van.

My choice

In the end I chose the polyester insulation.  Using high temperature spray adhesive I stuck it to the metal of the van, where there was no alternative support. Then it was easy to stuff into small holes to fill the numerous cavities and seemed quite good at retaining its shape and springing back out to fill the space after being forced though some tiny openings.

Combined with butyl mats for sound deadening and a closed cell foam under the floor boards it has transformed the van.  The problem now is that I can hear all those rattles from the dash and the front of the van that were previously covered up by the noise from the back.

My aim has been to find the best insulation for this particular job and it’s not been possible to write here about the different environmental impacts of the materials but  choosing polyester made from single use plastic waste feels better than using something made from new petrochemicals.

low impact van insulation
low impact van insulation

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