Vanlife Insulation Guide: Make an Educated Decision

Last Updated: October 4, 2021

Vanlife Insulation Guide: Make an Educated Decision

Van insulation... welcome to the most controversial topic since the creation of #Vanlife! After years of passionate debate, Internet experts still can't agree on the best insulation for DIY van conversions. Let's hit pause on the emotional debate and do it our way: with theoretical analysis and real-life follow up.

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Portrait-FarOutRide-Isabelle-Antoine-Van

1- Jumping to Conclusion

We’re not fans of shortcuts and hasty decisions, but there you have it. After 2 winters of full-time vanlife at temperatures as low as -22F (-30°C) and up to 95F (35°C), we recommend insulating your van with:

Thinsulate

ford-transit-camper-van-thinsulate-installation-1

We personally used Thinsulate in our van. It has kept us warm, no mold, no bugs, since 2017. It’s SO easy to work with, and there are no chemicals added (as fire retardant or bug prevention). We and our van love it.

(Shipping to USA and Canada. USA orders are tax free and ship from USA warehouse. Canadian orders are subject to taxes and ship from Canadian warehouse.)

That being said: knowledge is power! Make your own conclusion about van conversion insulation by reading the whole thing below…  🙂

2- Theory

2.1- Heat Transfer 101

The goal of adding insulation is to combat heat loss. Heat loss happens because of heat transfer (a.k.a. heat flow). Heat is always transferred from warm to cool and continues as long as there is a temperature difference; a larger temperature difference means more heat transfer potential.  There are 3 heat transfer mechanisms: Conduction, Radiation & Convection.

Credit: machinedesign.com

Conduction

Examples:

HOW:

Energy is stored in the vibration of atoms. More heat = more energy = more vibrations. The collision of atoms between each other transfers heat.

Insulating for conduction:

The more dense a material, the closer the atoms are from each other and the more they transfer energy to their adjacent atoms (by physically colliding with each other). Therefore:

Less dense materials are a better insulator for conduction.

Radiation

Examples:

HOW:

Any hot (or warm) object radiates electromagnetic waves and can heat up other objects at distance (and therefore lose heat themselves). Energy is transferred through the electromagnetic waves, therefore, thermal radiation can happen through vacuum (without the presence of matter).

Insulating for radiation:

A white shiny surface is poor at absorbing and radiating heat. It is, therefore, a good radiant barrier.

Convection

Examples:

HOW:

Heat is “transported” from one part of a fluid (or gas) to another by the bulk movement of the fluid itself. Hot regions are less dense, so they tend to rise and are replaced by cooler fluid from above. 

Insulating for Convection:

Insulating hollow structure (i.e. frames) and eliminating air gaps minimizes air movement and reduces heat loss through convection.

While heat transfer can be separated in to 3 separate mechanisms, heat loss normally implies all 3 of them together. For example, a hot cup of coffee:

  • Heat is transferred from the liquid to the cup surfaces (conduction + convection from the circulation),
  • From the cup to the air and objects nearby (convection+radiation), 
  • From the cup to the cold table underneath (conduction),
  • Blowing on coffee to cool it down (convection).
  • (Heat is also lost through evaporation -change of phase-, but that’s out of our scope).

2.2- R-Value

Insulation materials are good at resisting heat flow. To quantify how good an insulating material is and to allow easy comparisons between them, a neat dude came up with R-value.

R-VALUE

R-value denotes the capacity of an insulating material to resist heat flow. The higher the R-value, the greater the insulating power. It is normally noted (for example) “6.5 per inch“, which means applying one inch thickness of the material will provide 6.5 R-value; applying two inches will provide 13.0 R-value; and so on. R-value takes into account all three heat transfer mechanisms (conduction, radiation, convection). R-value is determined with the ASTM C518 test (“Standard Test Method for Steady-State Thermal Transmission Properties by Means of the Heat Flow Meter Apparatus”).

2.3- Condensation and Moisture Control

Vapor Barrier or not?

The purpose of a vapor barrier is to prevent moist air (from inside the van) from migrating towards cold surfaces. The idea is that moist air from respiration, cooking, drying gear, etc. won’t reach cold surfaces, thereby eliminating condensation issues. However, if, for any reason, moist air makes its way past the vapor barrier, it would be very hard to dry that moist air because it would be sandwiched between two vapor barrier layers (remember that metal is a vapor barrier too).

Even if one could achieve the perfect vapor barrier (which is unlikely, sorry), there are paths for outside air (charged with moisture) to infiltrate, and there are potential leak points as well:

Therefore, we believe that moist air will inevitably come in contact with cold structure, so our approach is to let the insulation layers “breathe” (no vapor barrier).

Condensation and moisture is quite complex, there is much more to talk about… we think this article should help you understand the phenomenon and help you make a better informed decision about your insulation:

CONDENSATION AND MOISTURE IN A VAN | WHY IT HAPPENS AND HOW TO CONTROL IT

2.4- Thermal Bridges

A thermal bridge is a path of least resistance for heat transfer. In other words, it’s a path for heat to “cheat” your insulation and find a way around it. It normally occurs via conduction through a dense material (such as metal).

Take for example the following picture. We added Thinsulate pretty much everywhere, except on the frames and pillars where we will attach our structure (cabinets, etc.). All the exposed metal is considered a thermal bridge, and heat will flow through it around the Thinsulate.

To mitigate the thermal bridges, a thermal break is added. We added LOW-E (EZ-COOL) since it’s pretty resistant to compression (applied by the structure attached to the van’s frames).

That’s important, especially if you’re using 80/20 aluminum extrusions for your build (structure, cabinets, etc.). Indeed, attaching the 80/20 aluminum directly to the van metal creates excellent thermal bridges; as a result, the 80/20 inside your van will be almost as cold as the van metal!

2.5- Air Loops

Hot air is less dense, so it tends to rise and be replaced by cooler air from above. That’s called an air loop and it’s a phenomenon that happens in non-insulated, hollow structures, like in the frames and pillars. So, to the question: “Is it worth shoving insulation inside frames knowing heat will find a way around (thermal bridges)?” We think it’s worth it. The total heat loss of your van is the sum of all the small pieces and bits… It all adds up! 

Air-Loop-Convection-Heat-Transfer
Van-Insulation-Convection-Hollow-Structure

3- Van Insulation Materials

At this point, we’re still on our quest to find THE BEST van insulation material… But in order to find out, let’s review our different options:

ford-transit-camper-van-thinsulate-installation-1

Thinsulate

PROS

CONS

Bottom line: it’s a popular tried-and-true product that gives an added value to higher-end builds.

Polyiso Rigid Board

PROS

CONS

XPS Rigid Board

PROS

CONS

Spray Foam

PROS

CONS

Rockwool

PROS

CONS

Reflectix

Once upon a time, someone decided to insulate his van with Reflectix and blogged about it. Then everyone started using it. 

By now, we know Reflectix is a very poor insulator. And on top of that, it requires an air gap in order to be effective.

It’s a good option to make your own window covers (to reflect the sun), but we prefer LOW-E as it is more resistant to tear and doesn’t have that annoying foil noise.

Low-E (EZ-Cool)

PROS

Low-E insulation (formerly EZ-COOL) is sold as a “radiant-barrier”. It doesn’t have much R-Value, but it’s convenient to use as a thermal break and for insulated window covers.

From Heros to Zeros:

Van Insulation Recycled Denim

Recycled Denim

Why we don't recommend it

It’s hydrophilic: it absorbs and retains moisture. People sometimes attempt to enclose it in garbage bags only to find out later that the bags are torn and the insulation is soaked or moldy.

Van-Insulation-Fiberglass-Pink

Fiberglass

Why we don't recommend it

It’s hydrophilic: it absorbs and retains moisture. People sometimes attempt to enclose it in garbage bags only to find out later that the bags are torn and the insulation is soaked or moldy.

Lizard Skin and other insulating Paint

Why we don't recommend it

By now we know that efficient insulation materials are low-density. A coat of paint is everything except low density…

The manufacturers don’t provide any data (i.e. R-value, etc.) to backup their claims; there’s probably a good reason why (it would be fairly easy to test and publish data).

According to this Scientific American article, the EPA does not recommend insulating paint: “We haven’t seen any independent studies that can verify their insulating qualities”. They noted some heat gain reduction on surfaces directly exposed to sun only, and that “the reflectivity of the painted surfaces decline considerably with time”. It’s all about reflectivity, not insulation capacity. Are you really gonna paint the exterior or your van with insulating paint..?

Until independent studies show a benefit of insulating paint through standardized test, save your money and your time.

4- Our Insulation Strategy

Going from theory to real-life implies making compromises; there is no perfect solution! The best vanlife insulation is not just about R-Value, it’s also about:

  • Ease of installation for the average DIYer
  • Risk of messing things up (i.e. warped van panels)
  • Condensation and moisture control
  • Conformity to curved and uneven surfaces
  • Material properties (i.e. maximum temperature, resistance to pressure)

With that in mind, here is how we insulated our campervan:

4.1- Floor

To be efficient, any compressible insulation material (thinsulate, wool, etc.) must be fully expanded. As a result, they’re not ideal for floor insulation. On the other hand, XPS is an excellent insulator, provides a solid and flat foundation for our floor, is quite cheap, and is readily available at your local hardware store.

So, does it work in real-life? Definitely! We installed our Webasto so it blows hot air in our living space near and parallel to our floor; as a result, the floor is nice and warm, even in sub-freezing temperatures. But don’t get us wrong: the farther you go from the Webasto, the colder the floor gets. Cold air falls, remember? So even a perfectly insulated floor won’t be nice and warm all over unless it’s heated somehow. No, we don’t think a radiant heated floor is necessary (but could be a nice luxury); a pair of slippers is just fine and much more energy efficient!

We chose XPS Rigid Board C-200 to insulate our floor. The C-200 is rated 20PSI capable; human footprint = 16 PSI.

Here are our layers from bottom-up:

  • 1/2″ thick XPS (to fill the corrugations)
  • 1″ thick XPS
  • MLV -not shown in the picture- (noise insulation, but we’d skip that layer if we had to start over)
  • 1/2″ thick Plywood
  • Vinyl Flooring -not shown in the picture-

We documented EVERYTHING about our floor installation here (insulation, sealing, bonding, plywood, vinyl, etc.):

4.2- Walls, Ceiling, Overhead cabin & Sliding Door

Installing Thinsulate insulation in a DIY conversion is a piece of cake: there’s no mess, no risk of messing things up, it’s not permanent, and it’s easy to work with. You’ll be all done in a weekend. Here is how it goes:

  1. Cut Thinsulate to size (using tailor scissors)
  2. Apply 3M 90 spray adhesive to the van wall and on the white face of the Thinsulate
  3. Wait 30-60 seconds for the adhesive to become tacky
  4. Press the Thinsulate against the wall
  5. That’s all!

How does it perform in real-life? Since we moved full-time in our van (2017), we’ve had everything between -22F (-30°C) and +95F (+35°C), and we’re in a good position to say it’s a tried-and-true van insulation material. If we had to build another van, we’d use Thinsulate insulation again without any hesitation.

ford-transit-camper-van-thinsulate-installation-18
Walls
ford-transit-camper-van-thinsulate-installation-13
Overhead Cabin Storage
sliding-door-after-thinsulate
Sliding Door
Thinsulate installed
All done. That was easy!

We documented EVERYTHING about the installation of our Thinsulate insulation (walls, ceiling, overhead cabin storage, sliding door, etc.) in the following article:

We covered all the remaining exposed metal and about 50% of Thinsulate surfaces with LOW-E insulation; this is to create thermal breaks and add some radiant barrier. We didn’t completely cover the Thinsulate in order to let it “breathe” (the LOW-E acts as a vapor barrier). As usual, we documented the whole thing:

4.3- Windows

You can spend a lot of money and time on the best insulation, but remember that glass is an excellent heat conductor (in other words, a horrible insulator). You can make cheap & dirty Reflectix covers to reflect the sun in summer, but if you are skiers like us, you will want something that performs better… To minimize heat loss during winter, we made insulated window covers out of low-e + thinsulate + fabric. They make a HUGE difference in sub-freezing temperatures, and they’re just plain essential below 5F (-15°C). Here is how we made them:

5- On Second Thought

You can read our second thoughts in each respective installation article listed above. But to sum it up: we would choose exactly the same van insulation strategy if we had to start over! It has served us very well.

Want to know more about winter vanlife? Driving in snow, 4×4, FWD vs RWD, electricity, finding water, finding camp spots, etc.? We wrote a debrief after our first winter full-time in the van (and plan on updating it every winter):

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About-Us-Narrow

Hello! We’re Isabelle and Antoine 🙂 In 2017, we sold our house (and everything in it), quit our engineering careers, and moved into our self-built campervan. Every day is an opportunity for a new adventure; we’re chasing our dreams, and hopefully it inspires others to do the same!