1. The Theory: Understanding How Heat Is Transmitted

Before we start talking about insulation for your van, it’s important to understand the ways in which you can move heat around.

In fact, in the case of an RV, heat can “move” (meaning enter, leave and move within) in three different ways: by radiation, by conduction and by convention.

In the next few paragraphs, I’ll briefly explain each of these terms and why they are important to understand in order to insulate your camper van in the most effective manner.

1.1 RADIATION: HEAT PASSING THROUGH AIR OR VACUUM

Radiation is the natural phenomenon whereby heat is transmitted through air or an empty body.

When you are in the sun and you feel warmed by its rays, that is solar radiation: the rays that without touching anything else first, bring heat where they touch.

In the case of your van, the sun’s rays can pass through the windows. Therefore, in addition to obviously heating the outer frame of your vehicle, solar radiation can also heat the interior of your vehicle, passing through the exposed glass of your windows.

While this process can be comfortable and pleasant in the winter (or at least in cold climates), in the summer it can really turn your van into a hot oven (like when you park a car in the sun in the summer).

To stop solar radiation through windows (or any other surface), we normally use reflective surfaces that depending on the direction they are installed, can keep heat out, or inside the vehicle (more on that later).

1.2 CONDUCTION: HEAT PASSING THROUGH CONTACT

Conduction is that thermal process whereby heat passes from a hot surface to a cooler one through contact.

If you’ve ever accidentally drank a coffee that was too hot and burned your tongue, know that you burned it by conduction (heat passed quickly from the hot coffee to your tongue as soon as it touched it).

In the case of your van, heat can pass by conduction through your floor, your walls and your ceiling.

Since most of your van is metal (which conducts just fine), heat can easily pass by conduction from the outside to the inside and back again.

To remedy this problem and to keep the heat out in the summer and in in the winter, you need to reduce the thermal conduction capacity of your van and to do this you use thermal insulation.

1.3 CONVECTION: THE CIRCULATION OF HEAT WITHIN A FLUID (LIQUID OR GAS)

Convection is the movement of heat in a fluid (liquid or gas), where heat rises upward, while cold (heavier) heat falls downward .

In the case of your van, the warmer air will tend to rise toward the ceiling, while the cooler air will tend to fall toward the floor.

Understanding convection is important to understanding Where to focus more with thermal insulation: in fact, insulating your van’s roof more will help you preserve heat more in the winter (since in RVing, every inch counts, it is important to know where to “invest” a few extra inches in insulation, and where you can avoid it).

That said, before we continue with the next chapters of the article, let’s see together what we mean by thermal insulation.

1.4 UNDERSTAND WHAT IS THERMAL INSULATION AND THE “THREE PREMISES” OF THE ARTICLE

If you’ve already surfed the internet a bit, you’ll have noticed that the topic of “thermal insulation” for a camper van is a bit of a mix between religion and science: everyone has a different opinion on what’s best to use and there are a thousand myths about all materials.

The purpose of this article is not to confuse you further, but simply to help you understand the theory of thermal insulation and to make the right choice for YOUR project.

For this reason, before I continue I want to make three key points clear to keep in mind:

• Heat insulation in a van is about keeping the heat where it is: if it’s out, keep it out (in the summer), and if it’s in, keep it in (in the winter). To do this, you need to use a heat-insulating material that acts as a heat barrier (so it doesn’t transfer heat well and struggles to get warm).

• Insulation material options there are many, and there is not one that is better than the others in all cases. It all depends on YOUR preferences and YOUR project. I will, in the next few chapters, show you all the insulation options with their advantages and disadvantages, so that you can make an informed and useful choice to meet your needs.

• In this article I will NOT go into the technicalities of how heat is transmitted or how thermal resistance is measured, but just make it as easy as possible for you to make your informed decision. This article is designed to make your life easier, explain everything you need to know in a simple way, and arrive at the end of the article with a solution in your pocket.

Made clear these premises, we’re ready to launch into the search for the perfect insulation for your converted camper. In the next few chapters, in order, I’ll explain what characteristics of the insulating materials you need to keep in mind, what materials exist on the market, and their properties and finally I’ll explain to you how I insulated my van.

2. Characteristics to consider when choosing the insulation material

Before I show you the various insulation options available on the market, I think it’s important to briefly explain the main characteristics in which the different materials differ.

In this way, you’ll have clear categories with which to compare the insulation options we’re going to look at below, and with which you can compare them based on your preferences and needs.

Below, you’ll find the six categories that I recommend you keep in mind when considering which insulation material to choose: insulation coefficient, water resistance, ease of installation, sustainability, toxicity, and of course cost (per square meter).

If you don’t care to learn the theory or you already know it, you can skip the following chapter and go directly to the Comparative Table of Insulation Materials.

2.1 INSULATION COEFFICIENT

The ability of a material to insulate (block heat transfer) is commonly measured by an insulation coefficient called the R-Value .

R measures the heat trapping capacity (thermal resistance) of a 1Inch (2.54cm) thick material.

The higher the R, the more insulating is the material. If 1-Inch of a material has R-value=6, it will insulate twice as much as a material with R-value=3, and half as much as 2-Inches of the same material (R=6+6=12).

2.2 WATERPROOFING

Steam and condensation can be problems in an enclosed, confined space like the interior of a camper van.

In fact, the hot vapor that tends to hover upward in the air, when it comes into contact with cooler materials can condense into water droplets (as happens on the windows of a parked car with someone inside) that could seep into your insulation.

Water near the sheet metal, in the long run means rust. Insulation that is not waterproof, could give mold a fertile place to grow. For this reason, it is good to understand all the moisture control techniques (heating, windows, fans, etc.) and to evaluate the installation of a vapor barrier and the use of waterproof insulation materials.

2.3 EASE OF INSTALLATION

If you want to throw the value of your time and sanity into the equation of your insulation choice, you’ll probably be happy to weigh ease of installation into your choice as well.

In fact, some insulation materials are extremely quick and easy to install: you take them, place them, and you’re done (we’ll see which ones next).

Others, however, need to be cut and processed. Still others stick, others make a lot of dirt, others are potentially toxic and must be installed with gloves and a mask… in short, each material must be installed differently and involves different work.

2.4 SUSTAINABILITY

Nowadays, more and more people are looking to increase the sustainability of their lifestyles in various areas of their lives.

If it’s important to you to know how insulation materials are produced and what impact their life cycle has on the surrounding environment, you’ll probably be interested in keeping this judgment criterion in mind.

In fact, different materials have diametrically opposed impacts: some are simple natural products, while others are products of more or less polluting chemical reactions.

2.5 TOXICITY

Some of the insulation materials in the ones I’ll show you below can be potentially toxic to your health.

Obviously, if installed well and with proper precautions, none of them will give you any problems (otherwise I wouldn’t even mention them!).

That said, I think it’s important to be informed of the hazards of different materials and the precautions needed both in installing them and sterilizing them once installed.

2.6 COST PER SQUARE METER

Dulcis in Fundo, but not less important: the cost!

In fact, as much as you may want everything (e.g. a sustainable, non-toxic, super-insulating, waterproof, easy-to-install product), if you’re on a tight budget unfortunately you have to make choices and compromises.

The cost of a material, undoubtedly will guide your choice, which is why it is included in this list. I decided to include it as a “cost per square foot” to help you compare different materials that are often sold in very different packages and sizes.

3. Summary of the most common Insulating Materials on the Market

Below, I leave you with a Comparative Table of the most commonly used Insulation Materials for DIY Conversions. I have created this table so that you can easily click on the material characteristic you are most interested in and sort the materials according to it.

NOTE: The values expressed in the table are indicative of an average product and are not accurate to the decimal point. Some producers may be more sustainable than others, and obviously prices can fluctuate over time. The table was created with the purpose of giving you a general picture of the available materials and their properties: then of course, to choose the best for your project, you will always have to evaluate the characteristics and convenience of the products you will find around you.

Table of Insulating Materials to insulate a Camper Do-It-Yourself

Now that you have the table to compare the characteristics of the various materials, I want to briefly tell you a little more about each of them and their properties.

Below, I leave you with a brief description of each thermal insulation material, each with its most relevant advantages and disadvantages.

Once I show you the different materials in detail, I’ll show you what I used to thermally insulate my VW Crafter and, with photos and videos, I’ll show you my entire step-by-step installation process.

3.1 OPTIONS OF HEAT-INSULATING MATERIALS FOR INSULATING A DO-IT-YOURSELF VAN

4. My Choice: How I Insulated My Van – Step by Step

After reading up on the characteristics of various insulating materials, and after researching the availability and prices around me, I decided to insulate my van in the following way:

• Floor: 2cm thick XPS panels
• Walls: 4cm thick XPS panels
• Ceiling: 4cm thick XPS panels
• In the Cavity: Polyurethane Foam
• Windows: Blackout Blinds/Thermal Insulating Blinds
• Thermal Bridges: Wood

The reasons for my choices were:

• I didn’t want materials that would absorb vapor and humidity, even to a degree. Because of this, I was forced to discard wools, although I have to say that sheep’s wool intrigued me a lot for all its other great qualities (sustainable, easy to install, non-toxic etc.).
• I chose the materials that gave me the most R-value while staying within 4cm of thickness (I wanted to fill the indentations but not overflow, so as not to lose horizontal space inside the van), and XPS panels and foam were among them.
• I wanted to stay within a budget of 200/250 Euros max. I would be covering more thermal bridges with some Thinsulate/Armaflex and maybe do a layer of reflextic where the wall would not touch the walls, but I would have gone too far over budget so I shelved those desires 😉

The downside:

• Unfortunately, the materials are among the least environmentally friendly of all. I plan to use the van full-time for the next few years to get around on my travels, and have been trying to build a “permanent” solution. The products were unfortunately not the most sustainable, but I hope they have a very long life before I have to dispose of them.

Below, I’ll show you step-by-step (with photos) all the steps I used to insulate my VW Crafter and explain in detail the reasons for each step.

4.1 HOW I INSULATED MY CAMPER VAN: STEP BY STEP

4.1.1 HOW TO INSULATE THE FLOOR

NOTE: I decided to use 2cm thick XPS panels because I didn’t want to raise the floor too much and to allow me to stand comfortably inside my van (I’m 1.87 and the inside of my crafter was about 1.94). In addition, because of convection (which we saw in the Chapter 1), heat tends to rise more upward and it is therefore more important to insulate the ceiling well than the floor. In fact, it is upwards that heat will tend to rise and escape in winter, and likewise it is from above that it is most likely to try to enter (where the sun’s rays beat).

Below, I’ll leave you with a photo of the finished insulated floor, on top of which I then installed the wood floor again (which despite being from a used van, was in good condition) and then the vinyl floor.

NOTE2: If you are interested in learning more about how I built the walls/floor/roof, I suggest you read the guide Van Conversion: Internal Roof, Floor and Walls.

Insulated Floor – Finished

4.1.2 HOW TO INSULATE THE WALLS

NOTE: As you can see in the video, polyurethane foam tends to expand a lot. That’s why I recommend you put in a little at a time and if necessary add more later. This foam is pretty darn sticky, so I would also recommend always using some work glovesand have a roll of paper towels handy to clean up any messes (as you can see from the next photos, I messed up a lot too 😉 )

NOTE 2: Foam boards in general (XPS, EPS AND Polyiso) rubbing against each other or with metal walls can create a very distinctive high-pitched sound, like a annoying rubbing between two pieces of polystyrene. To prevent this from happening every time the van moves, the pieces must be perfectly still. Personally, I’ve noticed that by filling all the cracks and holes with polyurethane foam, the rattling disappears. I recommend that you test your van before installing the final walls, so you can be sure that you won’t have to put up with the squeaky panel noise for life.

NOTE 3: Remember that after spraying polyurethane foam into the cavities of your van, there is hardly any turning back. So think carefully 3-4 times before spraying, and make sure you don’t need to access those areas again to mount other services.

NOTE 4: Doors can be insulated in the same manner as walls: make a puzzle of XPS panels and foam the cracks. The important thing, however, is to be careful when putting on the polyurethane foam, that it does not interfere/block the opening and closing mechanisms of the doors.

NOTE: To screw the wooden boards to the sheet metal of the van (cladding) I used some self-tapping countersunk head screws (size 4×40). If they have trouble getting in, I suggest you prepare the hole by drilling it with a metal drill bit with a diameter slightly smaller than that of the screw.

4.1.3 HOW TO INSULATE THE CEILING

5. Protecting Yourself from the Cold in Van – Extra Tips

Winter certainly is not the favorite season by most campervans.

The cold, the rain and especially the snow, require twice as much preparation as in summer and much more cumbersome equipment: coats, jackets, warm blankets, boots, snow chains etc.

Below I want to give you some tips and food for thought to plan how to protect you and your camper van in the best way from the cold of winter:

• Install an Air Heater: no matter how well the thermal insulation may have been installed, somehow you’ll have to create heat inside your vehicle when it’s cold outside (insulation slows down the transmission of heat to the outside, but it doesn’t stop it!). To do so and to not say goodbye to winter travel, the best solution is definitely to install an air heater. There are various types on the market and for all budgets! If you’re interested in learning more, I recommend my article: How to Heat a Van: The Complete Guide).

• Cover windows with a reflective material (e.g. Reflectix) facing inward: Windows, being virtually uninsulated, are one of the most obvious heat escape points inside a van. Installing an aluminum covered thermal window shade to the inside, will reflect heat and allow you to lose less of it through the glass.

• Alternatively, install a Thermal Blind: to black out the windows at night, I built myself entirely DIY custom-made window cover curtains. In doing so, I used a thermal blackout curtain that helps mitigate heat loss to the outside. In addition, I also used the same material to separate the interior of my vehicle (which cools quickly, having so many windows and not being insulated) with the living area.

• Think about protecting your water system: if temperatures go below freezing, there’s a real risk that the water in your water system could freeze. This can be very problematic (as it freezes, the water increases in volume!) and could cause damage to the components of your water system. Think carefully about where to install your water tanks (if you plan a fixed setup) so that they stay warm enough, or alternatively install a drain valve that allows you to empty your system in critical temperature situations. If you are interested in knowing how I installed my water system, I suggest you to read the article Do-It-Yourself Camper: A Guide to the Water System.

• Get a carpet (or two): The floor (normally being the least insulated area of a camper van) is likely to be freezing cold on winter mornings (unless you sleep with the heat on, but that depends a lot on the type of heating you plan to install). The easiest solution to get around this problem is to use some soft and warm mats 😉

• If you sleep with no heat on, be prepared with the right gear! A sleeping bag, a down jacket or even a 12V heated blanket, the options for staying warm at night are varied. The important thing to enjoying a winter trip is to be prepared for eventualities and what the road (and the weather!) may bring you.

• Keep an eye on the weather when planning a trip! We live in the future, predictions are at our fingertips, use them! Knowing whether you’ll face snow, rain, cold or find some nice weather days will definitely help you prepare your van the right way and not be found unprepared!

To conclude, thermal insulation is essential to be able to live more comfortably in your van even in the cold season, however equally important is your preparation for the trip you are going to do and the accessories you choose to install/take with you.

6. Protecting Yourself from the Heat in Van – Extra Tips

As in the case of cold weather, well-made insulation is essential to always find the inside of your motorhome pleasant and avoid the “oven” effect on hot summer days.

Despite this, in addition to thermal insulation, there are other tricks and behaviors that can certainly help you maintain a more enjoyable temperature inside your vehicle. Below, I list a few of them:

• If you don’t already have one, I recommend installing a ceiling fan that can expel stale air and suck in fresh air whenever possible. In fact, ceiling fans are the #1 tool for keeping your van’s humidity under control, as well as temperature and odors. Here is a Complete guide of how I installed my Maxxfan fan entirely Do-It-Yourself.

• Using a ceiling fan, you can create a pleasant draft by opening a window in your camper van.

• On warmer days, you can cover the windows of your van with thermal shades (you can find them already made for various vehicle models, or you can buy the materialand make them DIY)

• Think about installing a thermal blackout curtain between the interior of the vehicle (which normally heats up very quickly) and the living area (in this article – coming soon – I show you how I created and mounted my custom blackout blind)

• As obvious as it may be (and often difficult), parking in the shade is still one of the best ideas for staying cool in the summer.

• In extreme heat situations, you can think about using a small generator to run a portable air conditioner

Personally, with my insulation I’ ve never yet found myself with too unbearable a temperature inside my VW Crafter.

Nevertheless, some measures can certainly improve the livability of our little house on wheels. Understanding the behavior of heat (chapter 1) is certainly the basis for being able to protect yourself from extremes of temperature.

7. DIY Van Insulation Guide for Beginners: Conclusion

In this article we have seen how heat is transmitted, what is thermal insulation and what are the materials on the market most used to insulate the Do-it-yourself campers.

Next, after looking at the characteristics of each of the insulation materials, I showed you how I installed insulation on my VW Crafter using XPS panels, polyurethane foam, wood and related accessories.

Of course, I would like to remind you that is just one of the many ways in which you can insulate a camper van.

The truth is that there is no single perfect method to isolate a van, but many solutions that can work together, and it is up to you to choose and combine to meet the needs of YOUR project in your head.

Personally, I can advise you to don’t stress yourself any more than you have to for thermal insulation: it’s something that you don’t see at the end of the project and is therefore aesthetically irrelevant, it’s not one of those projects where small details change night-and-day the outcome, and on first experience it’s normal to mess around a bit. 😉

The important thing to do a good job instead, is to understand well how heat is transmitted and analyze with critical eyes your vehicle to identify possible thermal bridges, areas to be treated and critical issues.

I hope this guide has been helpful in clearing your head on the topic of insulation and helping you choose the right materials for your van!

If you have any questions about the topics covered in the article, think you need more information on certain details, find inaccuracies, or just want to help make it more complete for those who will read it after you, let me know in the comments below and I’ll get back to you as soon as I can 🙂

Thanks for reading, and as always, see you in the next guide! 😀