Vanlife Insulation Guide: Make an Educated Decision

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 what's the best insulation for DIY van conversions. Let's take a pause from this emotional debate and do it our way: with theoretical analysis and real-life follow up.

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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 (-30C) and up to 95F (35C), we recommend to insulate your van with:

Birthday-Hat-Doodle

*Thinsulate*

Thinsulate kept us warm, no mold, no bugs, since 2017. It’s the easiest material to work with and there are no chemicals added (as fire retardant or bug prevention). We and our van, love it.

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 transfert (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

  • Conduction is heat transfer through a material.

Examples:

  • A pot handle (see picture above!)
  • A spoon in a hot cup of tea
  • A van metal surfaces getting hot inside the cargo area on a sunny day
HOW:

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

Insulating for conduction:

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

Less dense materials are better insulator for conduction.

Radiation

  • Radiation is heat transfer through electromagnetic waves.

Examples:

  • The sun
  • A Mr. Heater Buddy (there is some convection too but it's mainly radiant)
  • A van dash getting hot when exposed to the sun
HOW:

Any hot (or warm) object radiate electromagnetic waves and can heat up other objets at distance (and therefore loose heat themselves). Unlike other mechanism (conduction, convection) no particles move when  heat is radiated; therefore, heat can be transferred through vacuum.

Insulating for radiation:

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

Convection

  • Convection is heat transfer through fluid (or gas) movement.

Examples:

  • Hot air rising above an intense heat source (i.e. electric heater); Cold water falling towards the bottom of a lake
  • A vehicle ventilation system (hot/cold air travels with the air being pushed by the fan)
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 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 is an insulating material and compare them between each others, 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“; it 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 test ASTM C518 (“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) of migrating towards cold surfaces. The idea is that moist air from respiration, cooking, drying gear, etc. won’t reach cold surfaces and therefore that eliminates 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 take 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 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 and 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 tend to rise and be replaced by cooler air from above. That’s called an air loop and it’s a phenomenon that happen in non-insulated hollow structure, such as in frames and in 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:

Spray Foam

  • R-Value: 6.5 per inch.

PROS

  • Conforms to curved surfaces.
  • Impermeable to water vapor.

CONS

  • Can distort the van panels if applied in thick layers.
  • Messy to apply.
  • Will block mechanism if no precautions are taken (e.g. doors).

Polyiso Rigid Board

  • R-Value: 5.6 per inch at 75F, 5.0 per inch at 15F.

PROS

  • Impermeable to water vapor.

CONS

  • R-value decrease substantially at cold temperature.
  • Create air gaps on funky surfaces (which is mostly the case in vans) = water traps.

XPS Rigid Board

  • R-Value: 5.0 per inch at 75F, 6.0 per inch at 15F.

PROS

  • Provides more reliable thermal performance than Polyiso.
  • Impermeable to water vapor.

CONS

  • Create air gaps on funky surfaces (which is mostly the case in vans) = water traps.
  • Maximum service temperature: 165F. (dark painted roof will get hotter than that in the sun! source: phys.org)

Thinsulate

  • R-Value: 3.3 per inch.

PROS

  • Very easy to install
  • Hydrophobic (doesn't retain moisture)
  • Doesn't off-gas
  • Doesn't loose fibers and not itchy
  • Good noise insulation
  • Can be stuffed in hard-to-reach places

CONS

  • More expensive

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

Rockwool

  • R-Value: 3.0 per inch.

PROS

  • Easy to install
  • Hydrophobic (doesn't retain moisture)
  • Doesn't off-gas

CONS

  • Itchy
  • Can release fibers

Sheep Wool

  • R-Value: 3.6 per inch.

Sheep wool is the new kid on the block in Vanlife, so long term real-world data is not really available except for what the manufacturer claims:

“A chemical-free passive filtration insulating material that manages moisture and reduces sound” editor’s note: as with many  insulation materials, there is boric acid added as fire retardant and  insect prevention.

It’s not exactly hydrophobic as it “manages” moisture: it absorbs moisture when ambiant air is above 65% RH and releases it below that. The manufacturer claims it prevent condensation on cold surfaces. 

Reflectix

  • R-Value: 1.0 per inch.

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 EZ-COOL as it is more resistant to tear and doesn’t have that annoying foil noise.

EZ-COOL

  • R-Value: ?

PROS

  • No foil noise
  • Resistant to pressure (when inserted between van and structure)

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

THINSULATE vs Sheep Wool

Sheep wool is gaining popularity in the van conversion world, so we ordered a sample to see for ourselves:

We ordered a small sample of Havelock Wool (picture above) that we will place into our headliner, side-to-side with the Thinsulate (picture below). We can’t really compare the insulation capacity (in theory both materials have very similar R-value), but we’ll be able to observe a critical properties: moisture management (keep reading…).

SOME THEORY:
– Thinsulate is an inorganic (synthetic) material, doesn’t off-gas and there are no chemical added to improve its properties.
– Sheep wool is an organic (natural) material, so has to be treated with boric acid as fire retardant and pesticide. Boric acid is NOT known to be harmful at lower concentration and is actually found in many other building materials (Roxul, denim, etc). It comes from Borates which can be found in nature, but it’s a misconception that everything that comes from nature is good for us; harmful chemicals are also found in nature! BOTTOM WORDS: Because of the low concentration we’re not concerned about it in the sheep wool (remember it’s common in many materials and products), but it’s been sugar-coated by some manufacturers so we just wanted to set the record straight.

FIRST OBSERVATIONS:
– The Thinsulate we had in the headliner (for the last two years) still looks like new (no mold, no bugs), yay!
– During the installation the Thinsulate does not easily release loose fibers, while the Sheep Wool releases quite a lot of them. (not really an issue, just an observation)
– The Thinsulate holds in place with 3M adhesive, which makes the installation simpler.
– Both materials are cut quite easily with good scissors.

FIRST THOUGHTS:
– Thinsulate has been good to us for the last 2 years… It was super easy and clean to install, it has kept us warm during skiing season (down to -22F/-30°C), and at last we got no molds or bugs in it.
– But if the “natural & sustainable” aspect of the sheep wool appeals to you, that’s a good enough reason to go for it! Let us know how it performs in the long run 🙂

From Heros to Zeros:

Van Insulation Recycled Denim

Recycled Denim

  • R-Value: 3.5 per inch.
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 teared out and insulation is soaked or moldy.

Fiberglass

  • R-Value: 3.2 per inch.
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 teared out and insulation is soaked or moldy.

Lizard Skin and other insulating Paint

  • R-Value: Negligible
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 American Scientific Article, 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

  • XPS RIGID BOARD

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 fondation for our floor, it’s quite cheap and 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 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 show on the picture- (noise insulation, but we’d skip that layer if we had to start over)
  • 1/2″ thick Plywood
  • Vinyl Flooring -not shown on the picture-

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

4.2- Walls, Ceiling, Overhead cabin & Sliding Door

  • THINSULATE

Installing Thinsulate insulation to 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 performs in real-life? Since we moved full-time in our van (2017), we had anything between -22F (-30C) and +95F (+35C) 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) in the following article:

  • EZ-COOL

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

4.3- Windows

  • DIY Insulated Window Covers

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, an 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 ez-cool + thinsulate + fabric. They make a HUGE difference in sub-freezing temperatures, and they’re plain essential below 5F (-15C). 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 campspot, etc.? We wrote a debrief after our first winter full-time in the van (and plan on update it every winter):

 

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about us

Nice To Meet You.

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. We’ve been on the road since then and every day is an opportunity for a new adventure; we’re chasing our dreams and hopefully it inspires others to do the same!

2 thoughts on “Vanlife Insulation Guide: Make an Educated Decision”

  1. “To be efficient, any compressible insulation material (thinsulate, wool, etc.) must be fully expanded. As a result, they’re not ideal for floor insulation. ”

    This doesn’t quite make sense to me, as it is written. It’s not like it will compress when you walk on it as long as you have supports below your floor…

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