Next year we are travelling somewhere very hot in my AK350. As the roof metalwork gets blisteringly hot in the climate of SW France it is going to get even hotter next year.

Clearly I am going to have to put some kind of insulation under the cab roof and also the roof of the back of the van.

I have seen all sorts of attempts at people doing this, most I have seen seem to either fall off or don't do the job.

So has anyone had real success at this and if so what material did you use and how did you fix it on?

Cheers.

Celotex/Kingspan (there are a number of proprietary names for this stuff) rigid board insulation -commonly used for roof insulation on loft conversions - held in place with extrudable foam. Available in all sorts of thickness. Thicker the better for insulation purposes, although this will cut down on space inside the van, so you'll need to choose a trade-off.

Google for "Celotex seconds" and you'll get sensible prices.

Bison contact adhesive is amazing. That'd do the job

I have seen the vent in the grey picture before Peter but not the blue one which I like. Is this something you have made?

Is this stuff flexible enough to fit on the cab roof which curves in 3 ways

Up to 25mm might be ok, if available. I know the 50mm would not bend, although you could cut some slots on the back to make it more flexible.

It's not flexible at all. You'd have to cut it to a best fit on the curves, and fix it in place by back filling the curves with the extrudable foam. (Wedge or cramp it in place while the foam cures.)

Here's an artist's impression: (note: not to scale!)

Top tip 1: extrudable foam expands massively, so less is more! It can be tempting to try to fill the space available, but you'll only end up with masses of waste.

Top tip 2: NEVER be tempted to clean up spilled extrudable foam before it has cured. Simply leave it until it is all expanded and dry, and then knock it off the surface that it's stuck to. If you try to clean up when it's wet/still expanding it'll stick forever!

That's great [love the diagram] I think the van back should be straight forward enough. It the cab area that curves in all directions I want to get right. Not only does it have to do the job but it needs to look reasonable. I love the rear flaps that Viking has pictured. I will be making some of those.

Thinking about it, there's another house-insulation product that might be more up your street: Triso Super10 multifoil insulation.

I've never used this stuff (it's pricey - about £12.50/m2 for a 16m2 roll). However, I'd imagine you could glue it in place (with a heat-proof adhesive) and then cover it with a vinyl, for improved aesthetics.