Insulating a Camper Van: What’s the best insulation?

Thinsulate insulation in camper

Insulation in a camper van is a highly debated topic. Many people have many different opinions as to what works the best or if insulation should even be used at all. After looking at all options available, we decided to use 3M Thinsulate and believe this to be the best option available on the market.

We actually went back and forth on multiple options and debated about which would be the best to use for our van build. It’s one of those things that can keep you up at night. After all, it is a foundational step that you want to get right.

There are many steps in the van build that you could simple change along the way but insulation isn’t as simple. Once insulation is installed, you will likely have walls, cabinets, ceiling and flooring mounted so it won’t be as easy to go back and change the insulation.

Among the factors we considered when choosing the type of insulation we would use included:

  • Ease of installation – this was number one for me because I didn’t want to spend a lot of time on this step and I didn’t want a messy job.
  • Time of installation – I had seen videos of people taking weeks or even months to finish insulating their vans. I wanted to do something that would take less time.
  • Health – I didn’t want to be breathing harmful chemicals from materials often found in insulation.
  • Weight – I wanted it to be as lightweight as possible.
  • Effectiveness – I wanted it to be effective at helping the control the temperature inside the van.
  • Noise reduction – A van is just a thin metal shell. It can be noisy so I wanted insulation that could help reduce that noise.

The Case for not insulating a van

empty cargo van
Empty cargo van before insulation

I really never considered not insulating our van but I did do some research about it. The school of thought is that insulating a van that is mostly in a warm climate isn’t as effective as insulating one that is in a cold climate.

There is probably some truth to this but I haven’t felt the effect of it yet. I do live in a warmer climate and since installing our Thinsulate insulation, It has been much more climate controlled than it was before.

Besides that, the noise level is much less than it was when the van was just a big metal box.

I suppose if you were ONLY going to use your van in hot climates, you could get by with Reflectix or some type of reflective barrier.

However, I feel that insulation combined with a gap and reflective barrier has worked best for our van build.

The options that we considered for van insulation

There were really on three options that we even considered. Most of which are among the most popular that you see for van builds.

These options include:

  • Polyiso board – the cheapest solution but the most difficult and time consuming to install
  • Thinsulate – the most expensive but easiest and least time consuming to install
  • Reflectix – this really isn’t an insulation but we did throw around the idea of only using this throughout the van.

At first, we decided to go with Polyiso board. It was cheap and available locally and was highly rated as far as the insulation factor goes. We purchased two one inch 4′ x 8′ boards of this at our local Home Depot and thought we had our plan figured out.

Polyiso insulation installed on floor
Polyiso insulation used on the floor

In fact, we actually did end up using 1/2 inch Polyiso on the floor. It made sense on the floor since we built a square joist system that made it easy to cut and install into the areas. It was like putting a puzzle together and it actually made a noticeable difference in the road noise. We were happy with that and proceeded to use the 1 inch version of the same thing on the rest of the van.

This sounded like a good plan until I started measuring and cutting and realized how difficult and messy it was going to be. It’s nearly impossible to cut this insulation perfect for each area so you have to use Great Stuff to feel in the gaps and hold it in place.

I’m not a fan of Great Stuff and didn’t want to touch it and after much debate on whether or not it would be worth the trouble, we decided to go back to the drawing board.

Thinsulate was the other option on the table and it was becoming more clear that it was the one to go with.

Why Thinsulate is the Best Option

Thinsulate along the sides of van

Thinsulate stood out as the clear winner for us because of a few key areas.

  1. It was easy to install. As stated before, I didn’t want to spend a lot of time on insulation but I wanted a good foundation.
  2. It has sound deadening properties. This was very important to me as I wanted my van to be as quiet as possible while parked as well as while driving down the road.
  3. It’s Super lightweight. You want to add as little weight as possible during your van build. Although the weight savings probably wasn’t much over Polyiso, it all adds up in the end.
  4. It doesn’t hold moisture. Very important in a van build where condensation could be present quite often.
  5. It has a decent R value. It isn’t much different in R value than the Polyiso board. With an R value of 5, it was sufficient for our needs.

We decided to go with Thinsulate in the end and I am so glad we did. It was actually fun installing it because I felt like I was getting something accomplished. It was easy to cut to size (as long as you have sharp scissors) and then stick up by using 3M spray.

I actually finished the whole van in only two days and they weren’t even full two days. It was actually just one full day when you consider I only spent half of the each day working on it.

Of course there are other options that you can use on your van but most of the other options got scratched off of our list very quickly.

Insulation on top of insulation

Polyiso on top of Thinsulate behind shower

Having already purchased Polyiso boards, I decided that I could make use of it in areas where there would still be gaps behind the walls. I also figured it would be good to use it in the shower walls so that the noise level would be cut down a little.

I’m not sure if it helped much but at least I made use of it since it was out of the return window.

I also had leftover Reflectix that I used to make the window coverings. I found the perfect place for this as I began planning the ceiling furring strips and cedar planking. There would be about an inch gap between the Thinsulate and the ceiling wood so I figured it would be a great place to add a reflective radiant barrier.

As you can see in the image, I added the Reflectix to the furring and there was still a gap between it and the Thinsulate which is the best way to install Reflectix according to the manufacturer.

I was also able to use the leftover Reflectix on the ceiling and along the walls to create additional radiant barriers.

In truth, I’m not sure how all this will work because in the end, it is still just a big metal box. There are still metal areas exposed in the van that are hot to the touch so are these areas offsetting all the hard work I did in insulation?

I don’t think so. I’m confident that what I have done with insulation is much better than not having done anything at all. Combine that with the fact that I didn’t spend a ton of time on it and I feel good about my combination of materials used.

How is it working out?

I haven’t fully finished our van yet in order to take it on an actual trip but I have spent a lot of time in it working on other parts of the build.

Insulation in the Winter

Having finished my insulation project in the autumn I have had the opportunity to test it out throughout the winter. I was installing walls, ceiling, shower, cabinets and other things during this time.

Throughout the winter I noticed that once I got in my van, closed the doors and began to work, the van became pleasantly warm and stayed that way for a good period of time.

I’m certain that this would not have been the case had I not insulated it so well. I likely will not be doing a whole lot of winter travel but If I do it will probably be to a place with a warmer climate.

Insulation in the summer

My plan was to have our van ready to go by March 31 so that we could go on some spring trips. However, life happened and I was still left with a lot to do when that deadline came.

So my build has continued through the summer. It is now July 4th as I write this and I still have plenty left to do. I have been working in the heat to get things done and I can finally see the light at the end of the tunnel.

What I have noticed is that it does get quite stuffy in the van during the heat of the day. This is to be expected I would imagine. However, if there is a breeze blowing, I can open the windows and the roof fan and it becomes fairly pleasant inside.

Once the sun goes down, the heat doesn’t stay around long as long as you have some airflow going through the van.

I am so glad that we decided to add an additional window in the rear of the van. I believe this window will be the key in keeping us cool.

I also think that having insulation in the summer is better than not having it. It was summer when we first purchased our van and it was super hot working inside of it. I feel like it is much more pleasant to work in now since it has been insulated.

However, the windows and the airflow created by them has a lot to do with it as well.

Would I do it over again?

If I was going to make another van into a camper van, I would probably do much of the same thing on the next one. I would absolutely choose Thinsulate as my main insulator.

However, I probably would not use any Polyiso board on any part of the van other than the floor. I believe this type of insulation works great for floor insulation.

I would also use Reflectix again but only on the ceiling. I went Reflectix crazy on this van build and put it in every nook and cranny on both the ceiling and the walls. Of course, this is mainly because I had a large amount of leftover and wanted to use it all.

Overall I’m happy with the outcome of my insulation project. I look forward to seeing how it will perform on an actual trip.


Having gone through the insulation process and obsessing over how to do it right, I can breathe easy now knowing that I did the best I could. I really don’t know if the insulation is going to be sufficient but I believe it will be.

If you are obsessing over insulating your van or RV, I have a few tips for you:

  • Just pick an insulation type and go with it. I believe that any insulation is better than none (unless it’s fiberglass batts or denim).
  • Don’t expect to keep out all heat or cold simply by insulating your van.
  • Nothing will be perfect so don’t spend too much time on this step in your build.

I spent way too much time worrying about whether I was going to insulate my van perfect or not. I thought it would matter more than it actually does. However, I’m really glad I insulated it as I believe I now have a solid foundation and that will provide more comfort.

Now it’s time to get on with the more fun parts of the van build.

Dan Collins

I consider myself an outdoor enthusiast. I love to travel and go to places that most people don't get a chance to go. I want to see it all and live life to the fullest while I'm alive. My camper van is helping me to do just that. I write about my experiences to help inspire others to do the same.

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