Van Conversion # 4 – Insulation

Pé na estrada!

Insulation is one of the issues that generates “more discussion” whene you are converting a van, especially since there are many options and it is not always easy to choose the ideal material.

In this article we will address this topic and explain why our choices.

First of all we must realize that the insulation will allow us to keep cooler temperatures inside the van, because it will serve as a barrier to the cold coming in from the outside and from the heat we produce inside (and vice versa).

Needless to say, it is not a good insulation that will cause us to have a hot van in the winter or cold in the summer, for this we need a source of heat or cooling, what the insulation will do is make the desired temperatures easier .

Insulating Materials

There are several insulating materials available on the market, with different prices and purposes. For a conscious and informed choice, it is necessary to be aware of some factors and the most important is the R – Value, which is basically a measure that tells us the degree of efficiency of these same materials.

Simply explanied, this value tells us the ability of X material to withstand the passage of heat, and is directly related to the thickness of the material.


    EPS – Expanded Polystyrene

This material is cheap and easy to find solution. However, in curved or hard-to-reach places can not be applied. The humidity resistence is not the best to.

We ended up using this stuff on the floor but if it was today, we had used the XPS, just because of the price difference it pays off.


XPS – Extruded Polystyrene

This is the material that is most used in the transformation of vans, mainly due to the quality / price ratio. It is similar to EPS, only it is denser, absorbs less moisture and has a slightly higher R-value.

It is ideal for panels and larger areas of the van.



RockWool is a material made from the fiber junction, which provides a good thermal resistance and is ideal for by the most difficult to reach places.

However in our opinion, when in contact with water and moisture, it tends to absorb.

Due to the fibers it is necessary to have some attention when it is applied and if possible to use mask.


Cork is also a good insulator, ecological and with good resistance to water, but to get a good layer you have to spend a lot of money.


Expansive Foam

There are those who decide to isolate the entire van with expansive foam, which is why it is necessary to have a professional.

For the hardest-to-reach sites, or for the space that sometimes lies between the main insulation, this is the best option.



In England and in other countries, people use this material a lot, called Celotex.

This material at the level of Thermal Resistance is the one that presents better performance, and basically it is something of the sort of XPS but more evolved.

The point is that it is very difficult to find in Portugal and the prices are quite high.

Our choice

We ended up using three different types of insulation.

First and foremost, we used the 30mm and 40mm XPS because it offers the best value for money, is relatively easy to cut, apply and is water resistant.

Then on some curved points, we used rockwool, and finally in all the missing spaces, we used expansive foam.

1º Step

The first step is to decide which insulation to use, and start cutting.

In our case we used the XPS, and we tried to cut as best as possible, which is not always easy because the truck has many reliefs.

It is important to try to cut the panels as best as possible because the insulation will serve as a barrier, and in the end all the sites should be covered.

As our bed will be on the side (width) in the back, we need at least that it is 175cm so that we can sleep comfortably, and if we isolate everything with XPS this would not happen, so we made a kind of ‘recess’ , where we used Rock Wool because it is more moldable and occupies better the reliefs of the structure of the station wagon.

With this two-sided solution we can save between 8/10 centimeters, which does not look like much else will make a difference in the end.

2º Step

After cutting it is time to put the XPS panels on the walls of the van.

In our case we just glued the ceiling, because the remaining panels after the posts do not move. We made Lisbon-Leiria-Lisbon (400km) with the insulation all placed on the walls and none of the panels fell … From what we decided we did not worry about the collage.

For the glue to take effect it is necessary to stay pressed for some time, so with some wooden slats we made some pressure points in the XPS.

3º Step

Once all the panels are in place, you need to place expansive foam in all spaces that have been left uninsulated.

You must be carefull with the foam, because it first expands greatly and if by chance put in a too small and ‘closed’ place it can dent the van and be visible from the outside.

This did not happen to us but we read in some places that this could happen, so the warning is here.

4 º Step

The last step is to place the anti-vapor barrier, this barrier will prevent the moisture from bathing, breathing and cooking to pass to the insulation and to the plate, where it can generate problems.

The electrical wires, the gas and water pipes will now be put on top of the anti-vapor barrier, because in our opinion this becomes easier if in the future it is necessary to change or solve a problem.

We leave here some videos and articles that we used to ” form ” a bit of our opinion, which together with our personal experience and with what we ask the perceivers of the subject have made us make these decisions in isolation.

Support videos / articles

Price of the materials

  •  XPS 125x60x3cm x 20 : 60€
  •  XPS 125x60x3cmn : 12 €
  • Rockwhool : 18€
  • Anti-Vape 30m2 : 42 €
  • Expansive foam x3 : 9€
  • Polystyrene casting foam : 8€

other articles about this conversion

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