After many requests we decided to write a separate article about the insulation that we used in our Freerider.
We started the conversion of our Sprinter 4×4 with serious below sub zero temperatures in mind. That meant that we would need a very good insulation, but also an as natural possible climate, to have as little condensation as possible.
As a Van is all steel this is not the best base to start a build. Steel and cold temperatures outside, warm temperatures inside means condensation. Especially when there are two people sleeping & breathing. We experienced this in campervans of friends, every morning big drops of water all over the camper.
That is why we started looking for other, out of the box, solutions. We came across a product called Spray Cork, cork but applied in spray form. It is a mixture of 80% cork granules and 20% water-based paint that comes in many color options. It’s surface is soft to feel and textured. It feels warm compared to the steel.
Spray Cork is waterproof but breathable and allows vapour to move through the material. It seals the surface completely so that there are no warm- or cold bridges. Cork is environmentally friendly and has very good insulation properties.
Spray Cork is mainly used for insulating homes on the outside, with very good insulation against sun, rain and frost. It can last decades on the outside and that will probably be even much better when applied to the inside.
To create a natural and comfortable climate in the Freerider we wanted to use Sheep wool for insulation. Wool has the property to take on moist when it is damp and lets go off damp and moist when it is dry. Thus creating a good humidity balance, just like your merino wool underwear.
The downsite of wool is that, when wet, it can affect the steel of the van (rust). That is also a main reason why we have chosen Spray Cork to be the base layer of our build. As it is waterproof and breathable there would be no problems with damp wool against the steel walls.
We contacted Petru from A to Z Spuitkurk in Breda (NL) and discussed our plans. We could even choose the colour we wanted and opted for dark grey. We brought the Sprinter to Petru and he started by cleaning and degreasing the whole inside. After this he masked everything that should be ‘saved’ from the Spray Cork.
Petru has covered the whole inside of the Freerider (every single piece of steel) in three layers of Spray Cork. From side to side and from top till bottom.
When we picked up the Sprinter we were impressed. The Spray Cork looked kind of cool and it felt warm compared to the bare steel next to it. As we drove back we noticed another very big advantage: the lack of noise! Where before the Sprinter was a soundbox, there was little noise with the Spray Cork.
The second step of the insulation was installing the Sheep wool in the walls and the X-trem in the floor and ceiling. We have chosen Doscha Sheep wool that was treated, so it does not smell. After almost five years we can say that it does not smell indeed! We applied around 5-10 cm of wool in the walls.
As we could not really make the wool work in the floor and the ceiling, we opted for a total of 5 cm. X-trem. This product is moisture resistant and has very good insulation properties.
We finished the walls with 0,5 cm waterproof Oukome wood and drilled holes all over them to let possible damp and moist out of the wool. The last layer consist of cork panels, which has very good insulation properties, and is water resistant as well and does breathe. So any damp or moist can get out.
However, insulation itself is not enough to avoid condensation. You can have the best insulation in the world, but with two people breathing in a relatively small space, it will get damp.
Ventilation is the second part of avoiding condensation. That is why we installed a Maxxfan in the front and a hatch in the back. The hatch has a ventilation position so the Maxxfan pulls the air from the back to the front.
After almost five years in harsh winter conditions up to -32 C. in Norway we can say that our insulation package has proven itself. The only spot where we have a little condensation is the aluminium roof hatch in the back. This is obvious because it is a clear cold-bridge. The same goes for the single windows of the Sprinter.
The rest is literally cork-dry. The climate in our Sprinter 4×4 is outstanding, it feels very comfortable and natural, in every season of the year.
Would we do it again? The Spray Cork is an investment but in our opinion it will pay back in spades. So, Yes! we would certainly do the whole package again in a Van.