Keeping warm inside your campervan when it’s cold outside will make travelling in a campervan an absolute pleasure. But, get it wrong, and you will soon find yourself checking into the nearest hotel for some much-needed warmth. This is why campervan insulation is so important.
If you want to stay comfortable inside your campervan, then insulating the vehicle correctly will have such a dramatic effect. When it comes to keeping the heat in or out, insulation is one of the most important steps you can do for your campervan conversion.
There is also quite a lot of confusion when it comes to the correct type of insulation to choose from for your van build.
So, to keep it as simple as possible, here are some frequently asked questions when insulating a campervan.
Frequently Asked Campervan Insulation Questions:
- What’s the best material to use?
- How do I install it correctly?
- Is a vapour barrier important?
- How much is it to insulate my campervan conversion?
- What are R and K-values?
- Do I still need to insulate if I am going to travel to hot countries?
In this article, we will try to give you all the answers you need about insulating a campervan. We also take an in-depth look at the most commonly used materials, their pros and cons, and whether you should use them.
Before we jump in, we must first understand the properties of heat transfer and see precisely how it works.
Campervan Insulation and Heat Transfer: What You Need To Know
There are three types of heat transfer: radiation, conduction, and convection;
Radiation is a method of heat transfer. It does not rely upon any contact between the heat source and the heated object. One of the most notable examples of radiation heat transfer is the heat of the sun beaming down onto the earth.
One of the primary sources for radiating heat coming into your campervan is going to be your windows. They allow sunlight to pass through, which heats the inside of the vehicle.
In winter, this is a great benefit as it will soon warm up the inside of the campervan. However, it can have the opposite effect in summer, making it extremely hot and stuffy inside. By installing reflective window coverings, this will help deflect unwanted sunlight coming into the campervan.
It will also have a huge benefit in keeping the van cool and creating a pleasant, ambient temperature.
Conduction is the transfer of heat between two solid bodies. A good example of conduction heat transfer is leaving a teaspoon in a hot cup of tea; due to conduction heat transfer, eventually, the end of the spoon sticking out of the cup will get hot.
When the sun shines down and heats the external body of your van, the heat will eventually make its way inside, through the body and the walls of the vehicle through heat conduction.
Installing the correct insulation can slow down the process of heat transfer. In winter, insulation will have the opposite effect, slowing down the heat transfer out of the vehicle.
Convection occurs when the heat is transferred through a gas or liquid by the hotter material moving into a cooler area. A brilliant example is a hot air balloon. The gas heater inside the balloon heats the air, and so the air moves towards the top of the balloon. It then causes the balloon to rise because of the trapped hot air. When the pilot wants to descend, they let out some of the hot air from the top. Cooler air is drawn in from the bottom, causing the balloon to lower.
Because of the way that convection works, when the van begins to warm up, the heat will naturally rise. By installing thicker insulation in your roof, this will help considerably slow down heat loss through convection. It will keep the van interior nice and warm for longer, as well as making the van more efficient as it will require less energy to keep the van warm.
And when it gets a little too hot, you can use a ventilation fan to draw out the warmer air near the ceiling. It will also draw cooled air into the vehicle from any low-lying vents or open windows, making the whole interior of the campervan cooler.
Simply put, insulation will slow heat transfer.
This will help make it easier to maintain the internal temperature of your campervan.
What is K-Value? (Lambda Value, Thermal Conductivity, Λ)
K-value, also known as the Lambda value, Thermal Conductivity, and sometimes represented as the Greek letter λ, indicates the ability of such material to conduct heat. Materials with lower K-value do not easily allow heat energy to pass through.
Ideally, you want to use material with a low K-value to insulate your campervan.
K-value is expressed in W/mK, which stands for Watts per meter-Kelvin. It means that if a material has a K-value of 1, a 1m cube of material transfers heat at a rate of 1 watt for every degree of the temperature difference between opposite faces.
What is R-Value? (Metric)
The R-value is a measure of resistance to heat flow through a given thickness of material.
In simple terms, the higher the R-value, the more thermal resistance the material has. Therefore, higher R-values means better insulating properties.
How do you calculate the R-value?
R-value is measured in metres squared Kelvin per Watt (m2K/W).
The R-Value is calculated as R = l/λ where l = the thickness of the material in metres and λ (lambda) is the thermal conductivity of the material in W/m.K.
You can use this equation to figure out what is the best material to use when insulating your campervan.
If you divide 100 mm thick Rockwool insulation (0.10) over its lambda value (λ=0.035W/mK), this will return an R-value of 2.85.
Another way of using this equation is to compare different insulation materials and their thickness to see what is the best product to use when space is at a premium.
Polyisocyanurate (P.I.R.) insulation board (Kingspan, Celotex) has an average lambda value of 0.022w/M2K.
Using the same equation as before, a 75mm thick piece of P.I.R. board has an R-value of 3.40.
Comparing both insulation materials clearly shows that PIR board gives greater thermal resistance despite being 25mm thinner than Rockwool.
When choosing the insulation for your campervan where space is limited, the insulation board is going to be the best material to use.
What Should I Look for in Campervan Insulation?
It can be quite a challenge when it comes to choosing the right insulation material for your campervan build. With many different types of insulation available on the market, selecting the correct type of insulation for each part of your internal structure can be a daunting task. Thankfully, we have done that for you.
While there are lots of different materials out there to choose from, not all of them may be the best choices when insulating a van.
Below, we have listed what you should look for when choosing the insulation materials for your campervan:
- High R-value per inch. As mentioned earlier, the higher the R-value, the greater its insulation properties will be. And, because space is at a premium, choosing the highest R-value insulation will require less space. Winner!
- Value for money. When it comes to insulating your van, it’s not necessary to spend a lot of cash kitting it out with the latest space-aged technology. Having said that, be careful if you decide to go down the super budget route. Some of the cheaper materials may not be up to scratch and could leave you with a headache further down the road. The best insulation materials do their job effectively and won’t break the bank.
- It needs to withstand vehicle motion and vibration. Remember, you are not insulating a static home. When driving, the campervan is going to vibrate and move around. You need to install the correct insulation that can withstand all the stresses of motion without falling apart.
- Resistance to moisture, mould, and mildew. Either the material is impervious to moisture or has moisture control properties and is naturally mould-resistant (like sheep wool).
- Non-toxic. As you will be living and breathing in a relatively small space, you don’t want harmful gases or microscopic particles from your insulation floating around the campervan. Make sure you check out what tools to use, including safety equipment.
What is a thermal bridge?
A thermal bridge (also called a cold bridge), is an area that has a significantly higher heat transfer than the surrounding materials.
One common mistake when insulating a campervan is that people often insulate the internal frames only and neglect to provide adequate insulation to the frame ribs. It can then create a thermal bridge.
By stuffing insulation between your van’s frame ribs, as well as other nooks and crannies, you will significantly improve the prevention of heat entering and leaving your vehicle.
Campervan Insulation Chart
|#||Material||K-Value||R-Value @ 100mm||Recommended Use|
|1||Reflective Bubble Foil||N/A||N/A||Windows|
|2||PIR Foam Board||0.024w/mk||4.16||Walls, Ceiling|
|3||XPS Foam Board||0.033w/mk||3.03||Walls, Ceiling, Floor|
|4||EPS Foam Board||0.036w/mk||2.77||Not Recommended|
|5||Polyurethane Spray Foam||0.025w/mk||4.00||Gaps & Fill-In, Adhesive|
|6||Fibreglass Wool||0.035w/mk||2.85||Not Recommended|
|7||Rock Wool||0.035w/mk||2.85||Door Panels|
|8||Sheep Wool||0.038w/mk||2.63||Door Panels & General|
As you can see from this chart, there are a few clear winners when it comes to choosing the right campervan insulation product.
But certain types of insulation may be good for some applications and not so good for others. Below, we take a closer look at each of these materials and their recommended uses.
Common Campervan Insulation Materials
Reflective bubble insulation is made from a polythene bubble membrane with two reflective aluminium foil surfaces on either side that act as a radiant heat barrier. Although this type of insulation is used in many types of campervan conversions, it is also a little bit misunderstood.
Watch any DIY campervan conversion video on YouTube or read any of the popular conversion blogs online and chances are, you will see people time and time again installing the reflective bubble insulation directly up against the internal metal walls.
Simply put – Installing bubble insulation directly to your van’s surface is not the correct way.
Reflective bubble insulation is primarily a radiant barrier. It’s very effective at reflecting radiant heat, but this is self-contradictory as soon as you install the material onto a solid surface.
Since radiant heat only travels through air or a vacuum, it’s essential to allow at least 1.0 inch (2.5cm) of air space between the reflective bubble insulation and the panels of the van for it to have any effect at all as a radiant barrier. 
Although the middle layers of bubble film will give the structure added strength and provide a little bit of a thermal barrier against conductive heat transfer, for the price you pay, many other materials will provide you with a higher R-value for much less cash.
On the one hand, bubble foil has some excellent uses. Because it’s so good at reflecting radiant heat, it performs well when installed as a blind in a window frame.
On a hot day, use bubble foil to shield your windows from the incoming sunlight. You will quickly notice a considerable difference in the amount of heat coming in.
Polyisocyanurate, known as PIR, is one of the most popular insulation materials available.
PIR boards are created by blending a selection of materials together to create a rigid, single-core of Polyisocyanurate.
This is then sandwiched between two high-performance aluminium foil facings. This will provide a radiant heat barrier, providing you install it correctly with the recommended air gap.
The whole manufacturing process creates a sturdy, durable and lightweight insulation board. Most PIR boards also have a vapour barrier on either side to prevent the build-up of damp.
What Are the Benefits of PIR Insulation?
PIR boards are one of the most efficient insulation materials used in construction as they have excellent thermal properties. Another excellent benefit is that these boards are unaffected by air infiltration, resistant to the passage of water vapour, and very easy to handle as the weight is minimal.
This will make installation a quick and straightforward process. This makes it a brilliant material to use for your campervan insulation.
PIR is completely non-toxic and doesn’t off-gas anything harmful. It’s also significantly more environmentally friendly than XPS foam board.
Is PIR Insulation Environmentally Friendly?
According to the Insulation Manufacturers Association, the net environmental effect of PIR insulation products is good news. They say that over a 50-year period, PIR boards will save at least 100 times more energy than embodied in the fossil fuel used to produce them in the first place.
Additionally, since 2002, all PIR boards are manufactured without the use of any ozone-depleting substances.
This is really excellent news!
But we must point out: Although these figures are likely based on residential and commercial installations, and not vehicle installations, we still believe that this is good news for people who are more environmentally conscious when it comes to their van build or the environment in general.
You can read more about the sustainability and environmental impacts of PIR insulation boards here.
Another popular type of ridge foam board is expanded polystyrene or XPS.
XPS insulation is manufactured through an extrusion process. This manufacturing process involves melting together the plastic resin and other ingredients.
The liquid formed is then continuously extruded through a die that expands during the cooling process. This produces closed-cell rigid insulation.
As for the price, XPS is cheaper than PIR foam boards but more expensive than EPS.
What Are the Benefits of XPS for Campervan Insulation?
XPS does not absorb moisture, preventing a favourable environment for mould to grow. In fact, it serves as a barrier against moisture.
Another excellent benefit is due to the way this foam board is manufactured; the closed-cell structure of XPS foam imparts superior long-term strength and durability that will stand up to the vibration of the van when driving.
EPS insulation, otherwise known as expanded polystyrene insulation, is similar to XPS insulation, but it goes through a slightly different manufacturing process.
The insulation board is manufactured using a mould to contain small foam beads. Heat or steam is then applied to the mould, which causes the small beads to expand and fuse together. (It’s basically the same stuff as typical Styrofoam.)
Unlike XPS insulation, EPS insulation has small voids between the beads, where they haven’t completely fused together. This means that water can slowly penetrate the foam board, making it less effective.
However, if you are working to a low budget, you may opt for EPS insulation, because it is still thermally efficient. It also one of the cheapest insulation products available.
What are the benefits of EPS insulation?
Benefits of EPS insulation include its cost-effective prices, and its lightweight properties make transportation and handling super easy.
Did you know there are two main types of polyurethane spray foam insulation?
They are called ‘Open Cell’ and ‘Closed Cell’.
Deciding what type of spray foam insulation you should use for your campervan insulation may be trickier than it seems. Both closed-cell and open-cell spray foam both make excellent insulation, but do it in slightly different ways.
In this article, we will examine open-cell versus closed-cell foam and help you pick the best product for your campervan build.
What is the Main Difference Between Open-Cell And Closed-Cell Foam Insulation?
Open and closed-cell foam are two different types of spray foam insulation. Both have their strengths and weaknesses, and one is not necessarily better than the other. It all comes down to learning the benefits of open-cell versus closed-cell foam and deciding the type that fits your requirements.
Spray foam insulation is referred to open cell or closed cell because of the difference between the little bubbles (of cells) that make up the foam.
This is a foam that is full of cells that aren’t entirely encapsulated. In other words, the cells are intentionally left open. This then makes the foam a softer, more flexible material to work with.
This is a foam that is made up of cells that are totally closed. The cells are squeezed together, so air and moisture are unable to penetrate the foam. Because of this, closed-cell foam is far more rigid and stable than open-cell foam. Using closed-cell spray foam will also form an impermeable vapour barrier. This can shield your van’s metal walls from condensation.
What is the R-Value of polyurethane spray foam?
Closed-cell foam returns a higher R-value than open-cell foam. Closed-cell has a value of approximately 4.00m2K/W per 100mm of foam compared to 2.56m2K/W per 100mm of open-cell foam.
What Type of Spray Foam Should I Use for My Campervan?
Polyurethane spray foam comes in two varieties: the big spray kits that professionals use to insulate houses and the smaller cans of spray foam.
But, spray foam kits are rather expensive – foaming your entire van would cost upwards of £250.
Canned spray foam is relatively inexpensive and does a great job at filling gaps, cracks, and hard-to-reach areas like your internal van frame.
Fibreglass insulation is one of the most popular types of home insulation, and it’s easy to see why: It is super affordable, easy to install, readily available in a variety of sizes and, most importantly, a brilliant insulator.
What are the Benefits Of Fibreglass Wool For Campervan Insulation?
Fibreglass wool is composed of fine glass fibres that are woven, lightly compressed and then cut into long rolls or batts. This is really practical when it comes to using it for campervan insulation as it can be cut to shape and stuffed in hard to reach places.
And for the price, it is not going to break the bank. But saying that, compared to insulation board, fibreglass has a relatively low R-value, meaning you will need more thickness to achieve the same insulation level.
What are the Negatives Of Fibreglass Wool For Campervan Insulation?
Fibreglass wool soaks up moisture, which you definitely don’t want sitting behind your interior walls. It can also deteriorate over time and may eventually fall apart. This can be accelerated with the vibration of driving around in your campervan, which can aid in the release of harmful particles into the air.
That is why it is vital to use the correct protective equipment when installing fibreglass wool.
Is Fiberglass Wool Sustainable?
Due to its composition, fibreglass is known for its low embodied energy. This is the total energy required to produce the product from the raw materials stage through to the delivery of fibreglass products.
The main ingredient in fibreglass is glass. Since glass is made from sand, this is an abundant, natural, non-depleting resource.
So yes, fibreglass is a natural choice when seeking energy-efficient, green, sustainable solutions.
Is Fiberglass Wool Recyclable?
Fibreglass is designed, tested and built to last… for decades. That means there is less waste heading to landfills, as fibreglass products have extremely long life cycles.
Some manufacturers do offer to take back off-cuts, but this will depend on the quality of the material as well as the quantity.
Eventually, fibreglass reaches its end of life, and you may find it difficult to recycle. Many waste collection authorities will take in fibreglass wool for a cost, but unfortunately, it may end up in a landfill or incinerated.
Rockwool insulation, also known as mineral wool, is a rock-based mineral fibre insulation comprised of Basalt rock and recycled Slag. Basalt is a volcanic rock abundant in the earth, and Slag is a by-product of the steel and copper industry. The minerals are melted and spun into fibres.
What Are the Benefits of Rockwool For Campervan Insulation?
Rockwool has a similar K-value to fibreglass, but its rigidity makes it more durable and comfortable to work with.
It is also renowned for its excellent acoustic properties. With its naturally dense, non-directional fibre structure, insulating your campervan with this material will effectively trap soundwaves and dampen vibration to provide enhanced noise reduction. This is useful if you are camping in a busy part of town and want a relaxing night’s sleep.
What are the Negatives Of Rockwool For Campervan Insulation?
Compared to fibreglass, Rockwool is a lot more expensive, and the R-value per 100mm m2K/w is still a lot lower than its foam board counterparts.
Are There Any Hazards with Rockwool Campervan Insulation?
It is advisable to wear protective clothing and a face mask whenever you work with Rockwool, as the installation can be quiet an itchy process. Another hazard is that inhaled Rockwool slivers can become lodged in your lungs. There have been some indications that this can lead to serious health problems. 
Is Rockwool Sustainable?
The excellent news is Rockwool is entirely sustainable. Rockwool is made from Basalt rock, which is continually replenished naturally from within the earth. Volcanoes and plate tectonics produce around 38,000 times more stone material every year than used to make Rockwool products.
Also, Rockwool has a very long lifespan, performing to the same high standard for decades.
What Is the Environmental Impact Of Rockwool?
When producing Rockwool, high-tech filters, pre-heaters, afterburners and other cleaning and collection systems are used to ensure an environmentally responsible approach.
In the UK, Rockwool is also one of eight factories across the group that utilises rainwater harvesting for the process of water. Rockwool is also fully supported by several external environmental accreditations.
Is Rockwool Recyclable?
Waste material collected from refurbished and demolished buildings, along with off-cuts from the installation process, all can all be transformed into new Rockwool products. In fact, 100% of Rockwool’s production waste is recycled, and the material itself is 97% recyclable.
For tens of thousands of years, sheep have been able to survive the harshest of elements using their wool coats. This does a fantastic job of protecting them from extreme cold and heat.
Due to the cramped nature of wool fibres, they form millions of tiny air pockets that trap air, helping to provide a brilliant thermal barrier, making this an excellent insulation material for your campervan.
What Are the Benefits Of Sheep Wool?
Not only is sheep wool an excellent alternative insulation material compared to manmade materials, but it is also extremely environmentally friendly, non-toxic, and has some really exceptional benefits.
Sheep wool can absorb moisture in the air without jeopardising its insulation ability. It will also wick condensation away from your van’s metal walls as well as being resistant to mould and mildew.
And if that wasn’t enough, it also has excellent sound-deadening properties.
Sheep wool is really a wonder material!
What Are the Negatives Of Sheep Wool?
Compared to other available insulation materials, sheep wool does not have the highest R-value per 100mm – being a little lower than fibreglass. But it’s relatively low price and its moisture management properties make it a really great option.
Because of its lower R-value per 100mm, you will need more thickness than you would with say PU spray foam or fibreglass. And when space is at a premium, other products may offer better benefits, using less space.
Is Sheep Wool Sustainable?
According to the International Wool Textile Industry, sheep wool is a 100% natural product and highly sustainable. The energy required to produce sheep wool compared to manmade equivalents is tiny – as most of the energy required is used to wash the wool before use.
Sheep are part of what is known as the natural carbon cycle. When grazing, they consume the organic carbon stored in plants and then convert it into wool. A massive 50% of the weight of wool is pure organic carbon.
Is Sheep Wool Recyclable?
Wool will eventually come to the end of its life and when this happens, you will find it very easy to recycle. It is also worth noting that the wool fibre itself is naturally biodegradable.
Campervan Insulation: What We Recommend
If you had to go with just one insulation product to install in your campervan, then we would recommend PIR insulation foam boards.
They have the highest R-value per 25mm of any common insulation materials, they are super easy to work with, non-toxic, and they are not too costly.
Our second choice would have to be extruded polystyrene (XPS) foam boards. Like PIR foam boards, they have a relatively high R-value per 25mm, as well as being a little cheaper than PIR foam boards.
- Walls: PIR foam board, stuck to the van body using PU spray foam or high strength spray adhesive. Fill any gaps with PU spray foam.
- Ceiling: PIR foam board, stuck to the van body using PU spray foam or high strength spray adhesive. Fill any gaps with PU spray foam.
- Gaps + Frame: Use PU spray foam or any of the wool fibres.
- Floor: Use PIR or XPS foam board.
- Windows: Use pre-cut bubble foil insulation window coverings with a radiant barrier on one side. Face the radiant barrier (shiny side) outwards on hot days to reflect heat away from the van. Reverse during cold weather to retain heat inside the campervan.
Why do you need ventilation in a campervan?
We have already created an in-depth article regards everything you need to know about campervan ventilation, so make sure to go and check it out.
But to keep it short:
To stay comfortable in your campervan when the weather is hot outside, having an electric vent fan that can expel warm air from the ceiling and draw in the fresh air from outside is an essential feature for creating a comfortable internal climate.
Also, as the internal space of your campervan is relatively small, breathing, cooking food and using natural gas will all produce moisture in the air.
The moisture in the air will eventually turn into condensation if the correct ventilation is not in place.
How do I stop the heat coming in through my windows?
In summer, the primary source of heat entering the vehicle is radiating heat directly from the sun. Stand in the shade on a hot summer’s day for 30 seconds and you will know exactly what we mean.
If you want to do the absolute maximum when it comes to combatting high internal vehicle temperatures, using reflective foil cut-outs that sit inside your window frames will make a massive difference.
They work by reflecting the sun’s rays from entering the vehicle. This helps to reduce the internal temperature.
Aftermarket kits are available for some van models and are pre-made to the correct window frame size. If you want to save a bit of money, you could always make your own.
Buy some bubble foil roll online, cut the foil to shape and then glue to stiff cardboard.
Likewise, in winter, flip your foil inserts around so now the shiny side is facing in, and this should help keep the heat from escaping the vehicle.
We have tried to cover campervan insulation in as much detail as possible, but with a market that is constantly changing, always carry out your own research on what is the best product for your situation.
Do you have any advice you would like to share with people who are about to take on their own insulation? If so, please leave your comments below.
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