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Insulating A Van Conversion: Essential Info

Insulating a van conversion project properly is hugely important. And it can feel like it takes an age, as you’re itching to get onto the next stage. But taking your time to get it right will pay dividends for your future van life comfort.

Insulating A Van

In this blog post about van conversion insulation we’ll take you through, what insulation actually is and why you need it. The different types of camper van insulation you can use, including what we chose and why. Plus all our best insulation installation tips and hacks.  

What Is Insulation?

Most simply put insulation is a material that slows heat transfer. And when it comes to insulating a van, this will work two ways. That is to say keeping warmth inside when it’s cold outside and keeping the heat out when it’s hot outside.

van conversion insulation guide

The temperature difference between two environments i.e. inside and outside doesn’t need to be that great in order for heat to transfer either way very quickly. So you’ll be in for some sweaty summers and chilly winters without adequate van conversion insulation.

It’s particularly important if you travel with pets or small children, because as a result you will have much better control over the temperature of your living environment. Furthermore, some materials are better than others at insulating a campervan. 

Best Van Insulation

There are a few key properties that you will want to consider when choosing the best van insulation for you. Firstly there’s the R-Value, or thermal resistance. Which is just the measure of how much insulating power the material has. The higher the R-value better.

campervan insulation

Secondly and equally as important is the toxicity of the substance. Some of this stuff is really not good for your health. Moreover in a small space in which you will be sleeping there’s definitely some products you want to steer away from.

Then you have moisture resistance, some are pretty crap and will mould. Something you definitely don’t want! Other things to consider when choosing the best insulation for van conversion is value for money and how environmentally friendly the product is. 

Campervan Insulation Types

Okay let’s run through all the different types of insulation for vans and tell you what we chose and why.

InsulationR-ValueToxicityMoisture ResistanceValue (£)Eco-Friendly
Spray FoamHighHighHighHighNo
Foam BoardMedLowHighHighNo
Sheep WoolMedLowHighHighYes
Recycled PlasticMedLowMedLowYes

Spray Foam

Closed cell spray foam insulation is the best van insulation when it comes to the highest R-Value. It is also extremely water resistant. However that’s where the plus points end.

Because although it is possible to buy DIY foam spray insulation kits, if you don’t know what you are doing you could easily cause the sheet metal of the van to become misshapen. Furthermore it contains toxic chemicals and the correct PPE needs to be worn. 

Because it should be applied by a professional it also means that spray foam insulation is relatively expensive. For a trained person it’s quick to apply and get into all the little itty bitty corners. But it’s also permanent so if you need access after, that ain’t an easy job.

Overall, using spray foam for campervan insulation isn’t something we’d recommend.

Rigid Foam Board

Also referred to as insulation board or sheet insulation, in the UK, rigid foam board is also just called by the different manufacturer names; Celotex, Kingspan or Recticel. But they are all the same thing.

Foam board insulation is a great insulator and is super handy that it is readily available in different thicknesses. It’s low in toxicity when in place, but you should wear a mask when cutting it and gloves as the edges of the foil backing can be quite sharp.

rigid foam board insulation
recticel foam board

But being foil backed makes it highly moisture resistant. Unfortunately the materials it’s made from mean that it’s not environmentally friendly and the cost per metre isn’t that cheap either. But while it isn’t the easiest to cut into shapes, for ceiling and flooring insulation it’s very quick.

You can just score it with a stanley knife and snap it for straight edges, For curves we’d recommend picking up an electric knife for precision. 

A thumbs up from us when it comes to the best van insulation.

Sheep wool

Not only does sheeps wool insulation have great insulating power, being completely natural and renewable means that it scores low on the toxicity scale and high on eco-friendly scale. You don’t need to wear a mask or anything to install it and it won’t irritate your skin.

Sheep wool is also highly moisture resistant and as a result doesn’t trap moisture which can lead to mould and mildew. However it isn’t the cheapest of van insulating materials so depending on how big your soon to be campervan is, the cost can add up.

In conclusion sheep wool (or Havelock wool as it’s also known) is a great choice for van insulation. Unless of course you are vegan, then it’s likely the worst option.


Historically the most common of insulation materials, fibreglass is an excellent insulator and is the generally cheapest of the bunch. It also won’t absorb moisture and is mould resistant. 

It is in part made from recycled glass, however it’s manufacturing process means that it isn’t an environmentally friendly option. 

And the materials it is made from are strong irritants for both skin and the respiratory system. In a living space it should be sealed to prevent harmful fibres circulating in the air. That is to say it’s toxicity rating is high.

For this reason we don’t think fibreglass insulation is a good choice for insulating a van. It’s far too hard to handle and toxic for a small space that you’ll be sleeping in. 

Recycled Plastic

Made from recycled plastic bottles, this van insulation ranks high in sustainability stakes and doesn’t contain any harmful chemicals. It’s safe and non-irritant. Meaning it can just be torn by hand and doesn’t require any PPE to be worn during installation.

Recycled Plastic Insulation
insulating a van

But most importantly recycled plastic insulation has a solid R-Value. What’s more, because it is an open non-woven material, it allows water vapour to pass through the insulation and does not support mould growth.

Compared with other van insulation options, it is certainly good value for money and vegan approved to boot. In order to perform at it’s best it should not be squashed, but as it is so easy to handle it is great for insulating hard to reach spaces. 

Recycled plastic nails it for us when it comes to the best van conversion insulation.

Insulating Van Walls

For our van wall insulation we used a mixture of 50mm rigid foam board (Recticel) and recycled plastic insulation. For the larger flatter panel sections we shaped foam board with the electric knife

We held them in place with some spray glue. And after that secured them in place, sealed the edges and filled the gaps around them using a minimum amount of expanding foam spray.  

how to insulate a van
best van insulation

For the rest of the walls we tore recycled plastic insulation to size and placed it in all the gaps. Being thorough to ensure it was behind and inside all the cross beams.

It’s important not to squish the insulation in, it needs its air pockets in it to work. In other words don’t try to stuff in pieces of insulation that are bigger than the space. It should just sit inside.

Van Vapour Barrier

We also placed a foil covered bubble wrap (reflectix) over the van wall insulation to better protect it from moisture caused by breathing/cooking/showering. It’s important that a van vapour barrier is completely sealed though as if not it could do more harm than good by trapping moisture in. 

vapour barrier van conversion

To seal it up you’re going to need aluminium foil tape, aluminum foil tape and more aluminium foil tape. Seriously the rolls of this we got through – definitely something to buy in bulk.

Insulating A Van Ceiling

The van conversion insulation in our ceiling mainly consists of squares of 50mm Recticel foam board. To stick the rigid foam board to the ceiling we used these super handy insulation sticky pins. They work really well.  

best insulation for vans
insulating a sprinter van

But we did also use recycled plastic insulation to fill the hollow cross beams. A time consuming job when it comes down to how to insulate a van properly. However one well worth doing so that those parts of the metal frame don’t just act as a thermal bridge for heat transfer in and out of the van.

Then we sealed all the edges of the foam board with aluminium foil tape, fastidiously checking for any dents in the foil backing of the foam board to seal those up too. 

How To Insulate A Van Floor 

As warm air rises, and keen to keep as much head room as possible, for our van conversion floor insulation we opted for a 25mm Recticel foam board. We framed the floor of our van out with wooden batons, so we just cut the foam board into squares and slotted it in. 

van conversion floor insulation

Then as with the ceiling, sealed all the edges and taped up any small holes from damage during installation with aluminum foil tape. You will go through foil tape like no tomorrow so get plenty. Different widths also come in handy.

Van Insulation Kit

P.S. Some links in this post are affiliate links. So if you buy through them we may earn a small commission from the seller. It’s at no extra cost to you so is a lovely way to say thanks for the free info we’re providing here.

Van Conversion Insulation Tips

Closing The Cab Off

Another decision to make is whether you will block the cab off from your living space. This is of course a design preference and if you are intent on installing swivel seats won’t be an option. But you should also consider it from your campervan insulation perspective.

Glass is a very poor heat conductor. And there’s an awful lot of it up front. So as well for security reasons and wanting to be able to use it for our kitchen and bathroom, we chose to block off our cab with a partition. 

Closing The Cab Off

Exactly the same as the floor, the spaces between the supporting wooden batons are filled with 25mm Recticel foam board insulation. If you cut them just to size they will hold in place without falling out until you put the outer plywood on. 

Because we closed our cab off we didn’t take out the cab ceiling lining and insulate underneath it. But this is something you will want to do when considering how to insulate a campervan if you’re keeping it open. 

Window Coverings

For any van windows you have in your living area, or in the cab too, if you decide to keep it open, don’t forget about window coverings. We made ours from the van vapour barrier cut to the exact shape of the window, backed with 4 way automotive stretch carpet and secured in place with magnets. 

window heat transfer

The silver foil needs to go window side – this will reflect the heat in summer. And although not the best insulator by a long way for keeping heat inside in winter, it is far better than bare glass. They are dual purpose as they are obviously great for privacy too. 

Wheel Arches

Because the wheel arches didn’t have a cavity in which to place insulation, we first sealed them up with some of the reflectix. Then stuffed the wheel arch boxes, that we made from plywood, with some of the recycled plastic insulation as a work around.

Wheel arch insulation

Noise Reduction

One thing that we didn’t mention when we were chatting through the different properties to consider when it comes to choosing the best van insulation is noise reduction.

So although it shouldn’t be one of your primary considerations it’s something to bear in mind as some insulators are better than others at this.  

The main thing that helps with noise reduction you are going to want to install before you begin insulating a van conversion, and that’s sound deadening. You can buy them in ready cut sheets or a roll and you basically just peel off the sticky back and stick them onto the metal van panels.

The material is a soundwave absorber and prevents noise reverberating off the metal.

By the end of finishing your camper van insulation your exciting project will resemble a spaceship. It’s a rewarding stage to get to during your DIY van build project.

If you have any unanswered questions or queries, be sure to hit us up in the comments. 

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