Van Conversion Campervan Insulation Part 2

We insulate our van conversion with campervan insulation. Along with recycled plastic insulation, we also with PIR insulation board for your van conversion insulation.
Van Conversion Campervan Insulation Part 2

Now that the fluffy stuff is in, it’s time to install the PIR Insulation Board. This stuff has excellent thermal properties; however, is not quite designed for installation in a campervan, what with the curves, kinks and uneven surfaces. So how does one install a rigid board in a campervan?


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 on the floor).

We ordered four 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 four 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. 🕶️

van conversion pir insulation
van conversion pir insulation


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 fits 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 testing it 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.

van conversion pir insulation
van conversion pir insulation


The four window cavities were (to a degree) rectangular. The back door cavities were not.

They were irregular in 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.

van conversion pir insulation

top tip

Carving the PIR board does take measuring and time. Some people choose to 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. 😌


Once all six 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). 

Flibbertigibbet. 😔

van conversion pir insulation
van conversion pir insulation


We tried sticking the stick pins on the support braces so they had a higher platform, but they just kept falling off. 

Instead of relying only on the stick pin adhesive, we broke out some Sikaflex EBT, and ran a bead all along the high points of the support braces. We then stuck 2 stick pins on the braces and 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 would hold the PIR board in place, allowing some movement not to squeak.

Problem solved. 👍

van conversion pir insulation
van conversion pir insulation

top tip

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. 

Weird, huh?!


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 them 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).

Then we filled the recess gap with some fluffy insulation, and put a piece of foil tape over the top to seal it in.

van conversion pir insulation


Since our sculpting was not perfect, we had 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, and 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. ⚖️

van conversion pir insulation
van conversion pir insulation


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.

van conversion pir insulation


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 high points, 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. 🔇


van conversion pir insulation

quick look

  1. Measure and cut PIR board
  2. Shape PIR board to fit cavities
  3. Attempt to stick pin PIR to van
  4. Use sealant and stick pins to attach PIR to van
  5. Cut recess, fit plate, angle grind, and cover up hole
  6. Modify and fix back door PIR board


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