Cutting the insulation cake
Now the fluffy stuff is in, for our window cavities (and the roof), we are using a 50mm PIR insulation board (double the thickness of the PIR we put in the floor).
We ordered 4 boards, which should be enough for everything, if we cut it economically.
A quick bit of maths later, we managed to fit all the rectangles on the 4 boards and begin to cut them up with a crafting knife. 🔪
Based on our previous experience, we went with a thin marker this time, so the thickness of the line will not affect the size of the board we cut.
Sunglasses were also needed as it was quite a sunny day, and oddly enough the shiny metal foil was doing its job well, reflecting the sun’s light back straight into our eyes. 🕶️
Curving the rectangles
Since the window cavities don’t have a straight line, we had some serious shaping to do. The other thing was that the internal perimeter of the window was smaller than the external perimeter, so we had to shape the edge of the PIR board so that it fit snugly in the cavity.
Using our various diagrams and central fixed lines, we slowly measured out the dimensions on the board, on both sides.
We then started with the larger side and cut out an even curved rectangle, then flipped it over so we could see the inner line, and used this to carve an angled cut – best explained in our video.
Once cut, it was a matter of testfit in the van, reshaping the PIR board and repeating until the board fit (ish). We also used the small sanding machine to smooth out some of the edges instead of taking off larger chunks.
Note: Sanding PIR board is a very dusty job, wear and mask, do it outside and avoid sanding it in the first place if you can.
Oh boy, the backdoors aren’t rectangles
The 4 window cavities were (to a degree) rectangular. The back door cavities were not.
They were an irregular shape, with only one straight side (that wasn’t even straight, we just decided to imagine that it was straight… desperate times call for desperate measures).
It took some dinner pancakes 🥞 and a fair part of an evening to cut, shape and fit into place.
Carving the PIR board does take measuring and time. Some people choose to just take the inner measurement, carve a simpler curved rectangle and fill the perimeter gaps with other insulation – spray foam or the plastic fluffy stuff.
We chose to get the PIR board to fit as close as possible to the gaps because it has better thermal properties then other insulation, and since it’s going to be a 4 season camper, we figured it worth the time to do.
Plus, sculpting was rather therapeutic in the end. 😌
Errr…how do we stick this?
Once all 6 sections were cut, we had to figure out how to attach them to the van.
Our initial idea was to use stick pins – which is how you can install PIR boards in houses.
This did not workout because of a few reasons:
- The stick pin base did not stick to the hot van metal very well.
- Due to the support braces, the PIR board did not sit flat up against van metal, which means the stick pins weren’t long enough to poke all the way through the PIR board.
- The jostling of the board caused the stickpins to make a bigger hole in the PIR board, worsening the thermal properties of it and allowing the PIR board to jiggle about.
- If we somehow managed to put a plate on the end of a stickpin, when we tried to hammer the excess tip, that loosened the plate (or just caused it to y’know… fall off).
Break out the sealant
We tried sticking the stick pins on the support braces, so they have a higher platform, but they just kept falling off.
Instead of relying only on the stick pin adhesive, we broke out some Sikaflex Pro 3, and ran a bead all along the highpoints of the support braces. We then stuck 2 stick pins on the braces, attached the PIR board to it.
The stick pins would hold the PIR board in place enough to give the sealant time to dry, and the flexible adhesive will hold the PIR board in place, and allow some movement for it to not squeak.
Problem solved. 👍
Ice blocks help. ❄️
When direct sunlight hits the van metalwork, the metal is fry-an-egg hot! 🍳 So although adhesives work better in warmer temperatures, they get too soft in hot temperatures, which makes them rather useless at sticking stuff (and drying… and holding weight).
To cool the van metal down, right before sticking a stick pin we held an ice block to the metalwork, to drop its temperature. Miraculously, it worked.
Finishing it up
Since the stick pins still did not poke far enough through the board, we cut a recess out where the stick pins were, allowing us to put on the metal plates securely (and we just used an angle grinder to shorten the ends down to sit flush with the rest of the PIR board).
Stop eating, you’re getting fat
Since our sculpting was not perfect, we had a big enough gaps between the insulation and the wall to fit some recycled plastic insulation in there.
We used our recycled plastic insulation and poked it in with a long thin metal stick.
We frankly don’t know where 90% of the insulation disappeared to, we kept putting clumps in, they kept going it… we used ¼ of a roll and the van just kept eating and eating and eating with no consideration for the weight limit. ⚖️
The back doors fell off
Well okay…the back door insulation fell off – let me explain.
Since the back doors are much deeper than the sides, and the braces didn’t allow us to stick a stick pin on it – the stick pins were even worse and didn’t even poke out.
We tried to put it up with a deeper recess and it seemed to work, so we went to bed with a “yay, job well done we did it”… aaaand then in the morning, it had fallen off.
To fix the problem, we fashioned some MDF pedestals for the stick pins to sit on, raising their base by around 15mm. We used our window glazing sealant to permanently attach the MDF blocks to the van, stuck the stick pins on them, applied more sealant on the highpoints, and restuck on the PIR board.
We can say after a few weeks of drying and a few trips out, nothing has fallen out or squeaks. 🔇