Floor insulation options

Hi, I am after some opinions please. I am insulating the floor of my 2006 Mitsubishi Express van. I have already bought XPS foam board.

  1. I think I should I put reflective foil beneath the foam, so as to reflect downwards any rising heat from the valley between the ribs?

Over the foam I was thinking to put some plywood as the easiest option.

  1. Should the plywood be ‘structural or non-structural’,

  2. and/or ‘marine’ grade?

  3. And how thin can i use, 10mm or ?

  4. Is it ok for the foil-foam-plywood just to float there, or should it really be glued down at some or all stages? (i certainly don’t want squeeking, and i want to build a bed above it)

Thanks you :slight_smile:


I would start with a factory mat. Not only are they great insulation, they are usually also fireproof. You should be able to find one at a wrecking yard. Nearly all passenger vans have them.

10mm should be fine. I don’t think it matters whether it is structural or not, but I would thoroughly waterproof it.

If using the XPS, I would secure it to the floor with something like liquid nails, and secure the the plywood to it in the same way.

If you’re going to drill any holes through the floor, make sure you drill them from underneath, so you don’t drill into anything you shouldn’t.


“Everything should be made as simple as possible." ~ Einstein

hi! thanks for your advice :slight_smile: I’m going to do it this Friday

Factory mat – you mean the carpet floor? We do have one of those.
So are you suggesting to place that at the top, eg: van floor, XPS foam, plywood, factory mat?


The factory mat I’m talking about is normally under the carpet, between the carpet & the floor of the van. This will be all you’ll need in the form of insulation, for the floor but you will also want to insulate the wheel wells.

Normally what I do is just keep the original mat & carpet, no matter how bad the original carpet is, then put easily washable throw rugs over it.

Personally, I don’t care for the wood or vinyl floors. I get the fact that may bee easier to clean, but they’re also slippery when wet, and the floors are always cold. Most people that have them wind up using throw rugs too. In my experience, the throw rugs stay put better when over carpet.

If the carpet is already out, you could take it to a DIY carwash, and give it a good cleaning.


“Everything should be made as simple as possible." ~ Einstein

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