Doing the floor

[CamperVanBeethoven]

I will soon have to redo the floor in the back of the van. The coachbuilder fixing it reckons that moisture trapped under the old floor (a couple of sheets of ply screwed to the metal floor) was responsible for the rust that is costing me a shedload to fix...

How should I reconstruct the floor to avoid this happening again? I'm also considering putting in insulation this time around. I'm thinking batons, insulation (Thermawrap), then ply on top; however, I have to bear in mind that insulation done improperly can cause moisture to form too

Any ideas and/or tips?

[Beaker]

The concensus of opinion seems to be:

#1. Rustproof - get rid of all rust then oxide primer or similar then waxoyl or similar.

#2. Insulation - depends on how much you want (or can allow) the floor to be raised. Some people go with thick Celotex slabs, spaced off the floor with battening that has been stuck down with Sikaflex before the Waxoyl.

Others, like myself used thin gold foil foam sheet layed down on the Waxoyl. Much quicker and easier, more headroom but almost certainly less effective heat-wise.

#3. Ply board, screwed to the batten, or or you use gold foil, screwed to the van floor - which is a potential problem - I need to keep a good eye on it!

#4. Carpet or lino etc.

The Celotex/batten method is almost certainly better, but raises the floor a lot. It also make periodic inspection and repair of the floor a little tricky.
The gold foil method preserves headroom, and can be easily lifted for inspection. I'm worried about the screw holes through the floor, but I treated them on the outside, and my floor was like a Swiss cheese anyway from all the racking that was in it when I bought it.

Time will tell I guess!

[CamperVanBeethoven]

Thanks for the answers

So, you can see the van in my pic. Raising the floor a bit isn't a problem!

You referred to 'gold foil insulation' ; I take it you didn't mean this stuff, because it's 33 mm thick?

http://www.tlxinsulation.co.uk/products/tlx-gold/

If I installed that (which is designed for roofs...) I take it the gold side would go to the top and not the bottom? Would I have to make the floor hugely thick, because it's meant to be airgapped?

Or, what was the type of gold foil insulation you meant?

The current (or I should say previous, as we ripped it up to weld the van) arrangement was just a piece of ply screwed onto the metalwork. Coachbuilder says I should put down marine ply, but I'd like to put some insulation down while I am at it. I've got some Thermawrap, which I bought to do the roof (was going to create a false roof and shove it in). That coild be a possibility...

[Beaker]

Sorry, I should have given you a link. Here is the gold foil insulation I'm refering to - it's only 5mm thick!

http://www.harrisonstrimsupplies.co.uk/premium-gold-underfloor-insulation-6m-deal-40594-p.asp

You can literally just lay it on the floor, cut round your wheel arches etc., then sit your floor panels straight on top.