Tom sticks his head through the bulkhead hole amongst the van insulation and vapour barrier above him.

Ultimate Insulation for a Van Conversion | How to Add 4 Layers to Keep You Cosy

| Our Citroen Relay Van Build

There are so many ways to do your van conversion insulation but as we’re planning on living in our van full time and we will be starting our journey in the UK, we needed to ensure it was going to be nice and cosy for cold winter days. It also has to cope well with damp days and humidity from living, breathing and cooking inside the van. 

Without further ado, here are our 4 layers of van conversion insulation and how we did it… 

If you’d prefer to watch, here’s our video…

1. Sound deadening for your van conversion

We really didn’t know what to expect from the Noico Sound Deadening Mats, but they really do work. It made such a difference to the tinny, van sound. Especially on the large back side panels. So, we spread out the sheets we had and used them on the most vital areas. It turned out, we had just the right amount to cover all the noisiest parts of the van.

How to:

  • Clean the area with meths.
  • Cut the sheet to size. Ensure you have a scrap piece of ply under the mat before you cut, then use a ruler or a straight edge of some kind and cut with a sharp Stanley knife.
  • Peel off the sticky backing.
  • Apply the mat/sheet to the panel.
  • Flatten. We used a wallpaper roller, but you could use a rolling pin, or anything.

Max putting up the sound deadening mats onto van panel

2. Foil faced adhesive foam insulation and sound deadening

The second layer of our van conversion insulation came in the form of the foil faced adhesive foam roll that was 8mm thick. This layer not only adds to the sound-deadening of the van, but it offers thermal insulation also. It was fairly easy to apply as it has an adhesive backing, it just takes time to measure, cut and stick all the pieces. (I used long wallpaper scissors, measuring out several pieces at a time and then cutting to size and sticking.)

a close up of the foil faced adhesive foam van insulation insulation on the door panel

Top Tip: Planning out a few areas together allows you to map them out/draw them out on the roll so you can maximise the space, so you’re not left with loads of randomly sized offcuts.

How to:

  • Clean the panels with meths to aid adhesion.
  • Measure your panels/spaces and draw out on the paper backing.
  • Cut out carefully, although it’s fairly forgiving stuff, so you don’t have to panic too much if the size is out a little.  
  • Peel off the paper – not always the easiest but in the grand scheme of things, it is a simple process. Again, we applied to as much of the van as possible.

Close up of the foil faced adhesive foam van insulation behind the wooden framing

3. Recycled Polyester fleece insulation

Layer three… Now it’s time for the cosy stuff! Van conversion insulation is great when it’s cold but is also good to keep cool air in when it’s warm outside. For us we wanted to ensure we did this well as we’re in the UK and we may need to face some chilly winter days working from our van.

This fluffy stuff turned our silver spaceship into Santa’s grotto. We used two different thicknesses of recycled polyester insulation – 50mm and 100mm.

How to:

  • You guessed it… Clean the area. We just gave the gaps a little hoover before filling to get as much of the dust out as possible.
  • The thinner stuff was easy to tear, so we tore off bits as we needed them. Fill any gaps or crevices within the van walls and ribs.

Top Tip: Don’t underestimate how much insulation you need but equally, don’t over fill the spaces. It’s the pockets of air in between the insulation that keeps you cosy, so you don’t want it to be too compressed.

To insulate the side panels:

  • Hold up the insulation to the panel to size it up.
  • Tear or cut the piece to size
  • Use spray adhesive to stick it in place. Tucking any corners or edges in neatly if possible or under our wooden framing/studwork. (It’s best to wear a mask, or at the very least have all doors and windows open when you use the adhesive spray as it has a pretty powerful odour.

Fleece van insulation inside the corner ceiling gaps of the van

4. Vapour barrier over your van conversion insulation

A vapour barrier stops any humidity, moisture, or dampness from cooking or simple living and breathing in the van, from getting through into the van insulation and outer cold metal shell of the van and causing condensation. This is aided by good ventilation.

This was the most awkward, annoying part of the van conversion insulation process – for us anyway. You see other people’s vapour barriers looking so neat and tidy but in reality it was a bit of a silver, shiny mess. But we got there in the end.

(We used a 1.5 metre x 50 metre roll.)

How to:

  • Grab some Gorilla or duct tape to secure in place (gravity is not on your side when you do the ceiling – two people is definitely recommended.)
  • Cut and secure panelled sections at a time. Once you have two sections up you can seal the edges with the aluminium tape to ensure you have an efficient vapour barrier.
  • Repeat everywhere!

Close up of the vapour barrier stuck around lighting wires coming through the ceiling

What about expanding foam as insulation?

In the end we used an exceedingly small amount of expanding foam for our van conversion insulation. We managed to get the polyester insulation into lots of the small gaps and didn’t feel the need to use the foam. We did use it on the air vents by the back door (they were going to be covered by our walls anyway.)

And that is it. Four layers later and we’re good to go with the walls. It feels like it too us forever to get here but we’re pleased we invested so much time and effort into putting (hopefully) effective insulation in. It will pay off on those cold winter days! 

Good luck! And as always, please feel free to send us any questions or leave them below.

What did we use in our van?

It’s all well and good saying how we did it and what we used but how much of all of this stuff did we use, well below in our helpul links section we’ve shared how much of each product we used in the end…

Helpful links

Here are some key products we used in this video. If we’ve mentioned anything you’re not sure about, please don’t hesitate to get in touch.

(As an Amazon Associate I earn a small amount from qualifying Amazon purchases.)

Thank you for reading our blog, we hoped you enjoyed it and we certainly hope it was helpful. If you did, and you haven’t already checked out our other blogs, please stick around. Or find our videos on our YouTube channel, where you can leave your questions and comments, and follow our van build series.


What is the best insulation for a van conversion?

As with most aspects of a van conversion, there are many ways to do things and no real ‘right’ way. Really it comes down to what is the best way for you. And that way you consider how you intend to use your van. For us, we plan on living in it full time for a while which means spending winter in it, plus we live in the UK which means the weather isn’t always warm, even in summer. This is why we have gone heavier with insulation. We have used 4 different layers, from sound deadening to polyester fleece insulation and a thorough vapour barrier everywhere to help during the damp, cold months. This is assisted by having good ventilation, coming from our two Thule vents, one of which, the Omnivent, has an electric fan to help circulate air in the van.

What kind of van conversion insulation did you use?

For the warm side of things, we have used recycled Polyester fleece insulation. This was nice to work with. We could tear bits off and fill gaps and holes with it, and then on the larger panels we simply stuck it on with adhesive spray before covering it all with our vapour barrier.

What is a vapour barrier?

A vapour barrier is a layer added to the inside or ‘warm side’ of your insulation that prevents any humidity or moisture (i.e. caused by breathing or cooking) from reaching the outer layer or ‘cold layer’ of your van and therefore preventing condensation from building.

Why is aluminium foil a good vapour barrier?

Aluminium foil prevents vapour diffusion, which means it does not allow moisture to pass through it, making an excellent choice as a vapour barrier.

Do screws break the vapour barrier?

Yes, technically they do, but the holes created are being filled, tightly, with screws, so there shouldn’t be any gaps and your ‘barrier’ should still be very much intact.

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