Van Conversion Floor Insulation Install

With the van floor framework installed, we install our van floor insulation using PIR insulation board to insulate our van conversion floor.
Van Conversion Floor Insulation Install

We bought 3 PIR Insulation boards, measured and cut them… Although…when it came to putting them in the first time…EVERY SINGLE ONE was slightly too big. 🤯


Once the beam sealant had dried, we measured the sizes of all the squares we had to fill with insulation.

Safe to say they were not all exact squares/rectangles, I mean, they looked square, but the beams were not always at exact right angles to one another, which proved to be a slight problem later.

We also used our layout planner a lot here to get the exact measurements of the floor instead of going back and forth remeasuring everything.

van conversion floor insulation


We used a 25mm PIR insulation board, as it is rigid, has good thermal properties, and is easy to work with.

We marked out our PIR board in the most economical way possible so we don’t waste material. Thanks, layout planner 😉

And then we tried to cut it up with a bread knife and crafting knife.

We much preferred the crafting knife since it didn’t produce PIR crumbs everywhere, although it did squeak a lot more, so Sam had to run out the room… foam squeaking is his ‘nails on the blackboard’. 😖


Once cut, we test to fit all our pieces, and none of them quite fit in their holes (blame Sam’s measuring).

Okay, it wasn’t actually Sam’s measuring skills; it was the incompatibility of a Sharpie marker line with a crafting knife cutting blade. The sharpie marks were a 2-3mm thick line, and the crafting knife blade only cuts a 1mm thick line, if that.

So, as the boards were cut, the cuts were made both on the inside and the outside of the line with no thought about the error.

Hence everything was a few mm out, and then when you add on the fact our squares weren’t entirely square…yeah.

After spending a few hours trimming them down, they all fit in their respective holes. 🛠️

van conversion floor insulation
van conversion floor insulation

top tip

For carving the PIR board to go around the wheel arches, we used the original van floor as a template for the arc we needed to cut and our layout planner to double-check these measurements. These combined worked very well at producing an accurate arc.


Having made the insulation fit, we taped over the blue beams with 100mm aluminium foil tape. This is to ensure an airtight seal for the whole top surface area of the floor, allowing for a good moisture barrier and a continuous radiant barrier.

100mm was wide enough to cover and overlap the beam with the adjoining insulation boards. We also covered parts in the PIR board that weren’t foil covered with this tape.

van conversion floor insulation
van conversion floor insulation

quick look

  1. Measure and mark PIR board
  2. Cut the PIR board
  3. Adjust and fit PIR board
  4. Cover gaps with aluminium tape


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