Campervan Insulation in a Self Built Sprinter Van

How easy is it to Insulate a campervan?

Insulation is essential to keep your van warm in the cold but also cool in the heat. Insulation is made out to be very easy on other blogs and YouTube, however, we found it took us 3 times longer than expected due to being so fiddly. You get left with lots of little gaps that can either be filled with the smaller sections of Celotex or the expandable foam . Caution when using the expandable foam as if you are too trigger happy it becomes very messy and you will end up covered in it!

Campervan Floor Insulation - is it necessary?

Campervan floor insulation seems to be a well debated subject on van forums. We asked a lot of other self build vanlifers and the overwhelming response was yes you should! Many said they read on other websites not to bother and their vans are now freezing cold and noisy!

The floor was tackled first with help of Greg Virgoe’s fantastic YouTube videos. Here is his video on insulating the van floor:


We started by battening the floor with 25mm pressure treated timber made into nice squares and into those we filled it with 25 mm Celotex which you can buy from most big DIY shops.. We then covered the wood and edges of the panels with aluminium foil tape to create a vapour barrier.

Top tip - Once you have done this make sure you get the floor back down as soon as possible otherwise you end up tightrope walking along all the wooden struts trying not to fall into the Celotex and crack it. Also make sure you know where the wooden battens cross so you don’t end up drilling through them when you put the holes in the floor for the heater pipes. 

 campervan floor insulation in a self built sprinter conversion

Insulating the Walls and Ceiling of the Campervan

Once the floor is done you can move onto the walls and celling. However be warned- if you are doing a Sprinter there are no squares or straight edges!

We used thicker 50mm Celotex for the walls and ceiling apart from where bed area is. To give us extra width for a transverse bed (Which we have now made into a  length ways pull out bed ) we used 25mm there.

Once you have acquired the skills of a sculptor coupled with a lot of patience it’s easy! Each section of Celotex will have to be carefully cut so it fits and then hammered in place usually because it’s just a little bit too tight!

Celotex insulation in the ceiling and walls of a sprinter campervan conversion After it’s all fitted you will be left with lots of gaps which can either be filled with small sections of celotex or expandable foam. Again- careful you don’t go overboard if you use foam- it really is very messy!

Celotex insulation and expandable foam for a sprinter campervan conversion

Installing a Vapour Barrier in a Campervan

Once the insulation is finished you need to add a vapour barrier. This will stop any moisture from breathing, cooking getting onto the insulation and making it soggy. This is key if you have used any earth wool insulation as it can absorb a lot of water may cause the van to rot.

We chose to use earth wool insulation, even though it can be a risk, as it’s a lot easier to fit into the panels. The thermal properties outweighed the potential risk for us. 

Next silver bubble wrap insulation  was installed which also acts a vapour barrier once glued and sealed into place.

Silver foil bubblewrap insulation in a sprinter campervan conversion


Next job is to make the wooden struts to attach the plywood cladding too. Once finished the van will look exactly the same as when you started.

Top Tip: Take a note of where the metal cross struts are in your van as once you have covered everything in insulation and vapour barrier it’s going to be pretty hard to work out where they are. We lost a bit of time wandering around the van pressing things and having to peel back sections of the vapour barrier to find the metal as you don’t want to drill through your van wall.

Silver foil bubblewrap insulation and earth wool vapour barrier in a sprinter van conversion

Materials List for Insulating a Campervan

 Greg Virgoes 2 Part Van Insulation Videos

Here are both of greg's videos which really helped us insulate our van:


If you have any questions then please drop us a line here.

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  • Dylan

    I’ve just bought a horsebox.

    I’ve watched a lot of these videos. Yours has by far been the best. The explanation of heat loss and lambda was useful to me. And explains a great deal about thermal properties. The dpm / vapour barrier was gold

    Your timing and delivery was amazing.

    Thank you very much for putting the time into making these videos.

    Cheers for the top tip on the sticky pads and shaping cellotex with an electric knife (i worked for a furniture manufacturer i knew that trick). Kudos for the shout out about replacing it.

    10/10 for the video.


  • Kate

    Hi, About to start my first build, I’m really struggling with the vapour barrier decision. Surely every screw we have to put through it along battons etc will make it useless and allow moisture in but not back out. Any advise would be gratefully accepted thank you.

  • Roof Insulation nz

    I am so happy I found your blog and I absolutely love your information about how to properly insulate a campervan and the tips you have shared are awesome. I liked and it is wonderful to know about so many things that are useful for all of us! Thanks a lot for this amazing blog!!I have seen similar information at one place, you can also see on

  • Roof Insulation Waikato

    Your article is quite helpful! I have so many questions, and you have answered many. Thank you! Such a nice and superb article, we have been looking for this information about how to properly insulate a campervan. Great post…I must say this, if you get time can visit for ideas on this topic.


    Beautiful conversion!!!

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