Insulating van conversion tips

Insulating your van not only helps it stay warm in winter but also provides a cool environment in summer. Here are all the Insulation Tips and Tricks | Van conversion.

As we’ll be living in the van full time, staying toasty warm and keeping cool is important so we knew this would be a vital part of the van conversion. 


After a lot of research, trial and error and practice, we decided to make a video all about how we insulated our van. It’s very informative and the videos should help you get an idea of the best way to insulate your van. You can view it here: 


Our Celotex arrived while we were doing the flooring, great timing! If you would like some information about how to insulate and lay the flooring: [click here]

Which Insulation?


After lots of research, we decided to go with Celotex boards for the walls and recycled plastic bottle insulation for the ribs and small gaps. The other (and more expensive) option would have been to have the van professionally spray foam insulated. But we wanted something lightweight that we could do ourselves. 

Where To Buy Insulation

The biggest tip we can give is to get your insulation online as it costs a fraction of the price you would spend at an actual shop. 
When we bought our insulation online there was a delivery charge of around £25-£50 but it still worked out much cheaper than getting it anywhere else.


If you’re in the UK like us, you can use a site called Insulation Hub. This isn’t sponsored or anything we just wanted to share our bargain find with you!
We bought far too much but we were able to sell the sheets we didn’t use.

How Much We Used

Here’s how much we used for our medium wheelbase, high top van.

  • Two sheets of 12mm for the floor
  • One sheet of 30mm for the ceiling
  • One sheet of 50mm for the walls
  • One and a half sheets of 75mm for the walls

Insulating The Walls

We started with the walls. The lower sections of the walls are incredibly thick so we decided to fill the available space with 75mm Celotex. May as well use the space if you have it. We also didn’t want any Celotex rattling around in there.

We found that any Celotex thicker than 12mm needed to be cut using a hand saw. Be warned that this is pretty messy and you’ll probably end up with lots of bits in your hair and up your nose. If you have one, its a good idea to wear a mask. This wouldn’t be the most fun on a windy day.

As our wall cavities are thicker on the bottom getting thinner towards the top, we used 50mm for the midsections of the walls followed by 30mm on the ceiling. Your’s might be different so just grab a tape measure and check the depth of your van walls in lots of different places to get an idea.

We chose to friction fit for our Celotex. We did this by being precise with our measurements. This meant that we didn’t have to use spray glue on the walls.

Insulating The Small Gaps

After the walls were done we moved on to stuffing the ribs with recycled plastic bottle insulation which you can buy in a 6m roll for around £16.

We ended up having to take some of the recycled bottle insulation out of one of the wall cavities as we realized we need to feed the wires for the roof fan and lights through it.

As we’re not electricians we have chosen to have the rest of our wiring on the outside of the walls, hidden at the back of the cabinets. This is because if we mess it up then we can easily access it to fix it. 

For the recycled bottle insulation we tried to saw it, cut it with scissors, but in the end, the easiest way was to just tear it apart it small strips and stuff it in. Remember not to compact it though as this will reduce it’s insulation properties.

It needs to be fully expanded for the air to be trapped around it. We did most of this with just our hands but sometimes took a screwdriver to help poke it where our fingers couldn’t reach. 

Spray Foam Insulation

When the walls were finished we filled in the crevices around it with expanding foam. This stuff was pretty messy. It was way more liquidy than we thought it would be and a little bit goes a long way. 


We found the best way to use it was upside down. It probably would help to have a contraption to keep the Celotex firmly pushed down but we just stood and held it in place for a few minutes until the foam stopped growing. Sometimes the foam can expand so much it tries to push the Celotex out!

Insulating The Ceiling

Then we tackled the ceiling. We used the same method as the wall except we had to use spray glue and prop it up with something while it set. We used random things from my dad’s garage, like broomsticks and chairs.

Maybe it was a mixture of our unstable structures and the spray glue being pretty rubbish, but the Celotex didn’t want to stay stuck to the ceiling. Late one night we thought the van was being broken into as the alarm sounded. Turns out it was just one of the insulation boards falling.

We ended up pulling them down and resticking them up with sikaflex and aluminium tape. Not only does the tape create a perfect vapor barrier but it also holds Celotex up really well. 

Insulating The Sliding Door

We did the same for the sliding door, using out leftover pieces to fill the gaps. It was quite bulky though so my dad got geared up and shaved it down to allow a flatter fit. 

For some reason unknown to any of us, after a couple of weeks, it completely warped and ended up sticking out of the vapour barrier… So we had to remove it and use more recycled plastic bottle insulation. 


After that, we used a vapour barrier and aluminum tape to completely cover every bit of insulation. The vapor barrier is to stop breath and cooking moisture getting to the insulation. 

I hope you found this useful!


If you would like to check out our complete van build series on YouTube, click here: www.youtube.com/ourwildhorizons


You can access our entire van build guide here completely free:

https://sheisthelostgirl.com/category/van-life/


Thanks for reading


The Lost Girl 

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About Me

Hi! I am Beth Johnstone, a travel journalist and photographer.

I began travelling in 2014 with what I thought would be a short holiday. I’ve now been travelling around the world full time for five years, taking photographs, writing about the places I’ve been and immersing myself in new cultures.

I am passionate about capturing the whole experience not just with images, but with words too. My blog is a positive place where I welcome readers to learn about the best places to stay, along with tips and advice on long term travel.

“Stop waiting for Friday, for summer, for someone to fall in love with you, for life. Happiness is achieved when you stop waiting for it and make the most of the moment you are in now.”