"The great forgotten"
It is the first thing we should focus on when starting to convert our van, but still many times it is the great forgotten, as it is not given the importance it deserves.
Good insulation will help keep the interior of our van cooler than the exterior in the Summer, and warmer in the Winter. Still, the insulation is not magic, so the we might still feel hot inside our van in the summer, especially if we park in the sun and have glass windows. The same as if we do not have some kind of heating, we will feel cold in winter, especially in the early morning, which will make getting out of bed seem like an impossible mission!
The first thing we should focus on is what type of insulation is best for us based on our needs, for example, where we live, the type of use we want to give the van, and of course, our budget.
We have to make sure that we insulate the entire van, both walls, floor and ceiling. For those large gaps in the walls and the gaps between the beams on the sides, it is best to introduce flexible material with which we can cover the entire surface, such as Recycled Plastic Fibre or Rock Wool. To work with this last one, we must use gloves, mask and glasses, as some filaments might come off during its placement. It is important to remember that Rock Wool is an excellent thermal and acoustic insulator, but it must be used together with a vapor barrier, which will protect us from the dreaded condensation. Many brands of Rock Wool on the market already come with a layer of Kraft or aluminum foil on the back. In case we opt for the simple one, we should add a vapor barrier, either made of reflective material or any other waterproof material used in construction.
Another option is to use more rigid materials, such as Extruded Polystyrene(XPS) or Expanded Polystyrene(EPS), better known as Poliespan. Both are vapor-tight, but are not malleable, so they will be good for large surfaces like the floor or large wall holes. Their disadvantages are that both are flammable and their manufacturing process is quite polluting.
Finally, probably the best insulation for our van is Kailflex or Armaflex, which is an elastomeric foam that prevents condensation as well as insulating, so we would not need to place a vapor barrier on top. It is fire resistant and flexible, which will make its placement much easier, especially in irregular areas. Some Armaflex brands come with a self-adhesive layer on the back that will make installation even easier. The only downside is its price, since it is the most expensive insulation, but it will be worth spending more money on it if we can afford it, than having to regret it later on due to condensation problems or poor insulation.
If your van has windows in the habitable area, it is recommended to use thermal covers (Isoflex), which will protect you both in Summer, reflecting the sun's rays outside, and in Winter, keeping the heat inside the cabin . In my first van, I made my own window covers, using a camping mat cut to size, with the reflective part on the outside, lined with fabric on the other side and with four suction cups, one in each corner.
The truth is that I noticed quite a difference on the nights when I put the window covers on, but when it was very cold I realised that they were not enough and I would need another type of window insulation with more layers.
These Isoflex covers are easy to find online and at an affordable price, being able to choose according to your van model and the type of windows you want to cover.