Floor insulation in a static caravan

[Class of '55]

Hi, ive just retired to an old caravan in need of a major refurb. The first job i have is to renew the rotted chipboard flooring at the back end (about 4x5 sq/m)
The under insulation currently is mineral with an outer poly covering (underneath) but ive no further details until i start ripping the floors out.
Id like some advice on the best way of topping up/renewing the insulation. I guess mineral is the obvious although I had considerd topping up with Celotex but i always like to refer to the experts. And I read some suggestions that there's little to be gained with this approach anyway? W ould underfloor heating be the answer.
Im planning to lay 18mm Hardwood ply and possibly painting the underneath with bitumen or PVA as a further measure of weathering although it wont be directly exposed.

Ill be tackling the walls after this but that another topic for another day altho ill always be grateful with any help offered.

I think it may be abundantly clear by now that I dont really know what to do for the best so I'm hoping somewhere here can throw some advice my way.

i have read many posts on this subject but id welcome a current view. Covid robbed me of most of my grey cells and i do struggle with concise thinking sometimes, cheers

 

[Mr Chibs]

Hello, Have you any photos?

I presume you will be intending to install the insulation from underneath the floor? As doing internally will rob you of head height.

Rockwool is cheaper than celotex but roughly half the efficiency. I would be tempted to stick celotex straight to the plywood floor (from underneath), tape and seal all gaps with a foam gun and aluminium duct tape, you shouldn't need to paint the plywood.
As for thickness, depends on what you can budget for... I'd say 75mm minimum... you can buy seconds, that may say some money.

If ufh is possible in a caravan, perhaps spreader plates might be worth reading up on, again though, this might impact on head height.

Will be an interesting project!

 

[Class of '55]

Hi 'Mr Chibs' thanks for the reply.

I dont have any photos currently but as work progresses ill post some.

I had the same thoughts as yourself ill fit Celotex fitted between the joists and lay the ply directly over. If i tape it off and use the foam from above ie. when the floors off, i assume that will be sufficient?

A lot will require a 'suck it and see' approach, always the unknown that keeps us on our toes with projects like this.

Just looked at spreader plates and they do seem like an option, a lot will depend on costs.

Im sure this will be an interesting project, trying to make a tin can habitable for 10 months of the year is gonna be a challenge for sure but it'll keep me out of mischief for a bit i guess

 

[Class of '55]

Thought I'd continue here to chronicle the work and keep it all neat and tidy.
I did search in the archives but couldn't quite get what i needed.
A nice simple question (aren't they all ).
I have to fix the new ply floor directly to the steel beams of the chassis, about 3 in total. What screws do you think would be suitable? I think what I'm asking for is a trade name and trusting it to the guys that will take time to read this rather than the vague reviews in trade outlets. I generally find 'does what it says on the tin' not that helpful.
Any help as ever appreciated and, when i find out how, I'll start posting some pics

 

[foxhole]

Lots of online videos with tips for renovating caravans.

 

[Deleted member 174758]

I have to fix the new ply floor directly to the steel beams of the chassis, about 3 in total. What screws do you think would be suitable?

Self drilling wing screws, like these. I tend to use Hilti or TimCo, but they are both trade outlets with minimum order quantities, account discount structures, etc so probably of no use to you. I have used the SFX stuff on a few projects, though

 

[robinbanks]

Deleting on how complex the framework under the floor you might like to get a two part spray foam for insulating it

 

[Class of '55]

Thanks Guys really appreciate your help

I've ordered the screws from SFX and I'll give it a go when i eventually get a bit of flooring down, getting the old stuff up is proving s lot more difficult than i thought it might be.
Found a good price/supplier for 80mm Celotex which has been delivered but ill consider the foam option for the remainder where i won't need to replace the flooring.
As you'd expect trying to make a tin can habitable is proving, well, interesting!
So i doubt this will be my last enquiry so again thanks again

 

[Mr Chibs]

Good luck, keep going, will look forward to the images/updates.