Insulated Floating Floor Over Stone

[JKBDIY]

Hello,

I am in the process of insulating a kitchen in a granite home; at the moment all lathe and plaster has been removed from the walls and a nasty epoxy covering removed from the stone floors so I have an empty stone box. I plan to stud out the walls and insulate, that's another topic for the 'building' forum, but I'd also like to insulate the floor and stick laminate over top.

Please confirm (or otherwise) the robustness of my plan:

Sand or self leveller to raise low spots
Damp proof stone floor (plastic sheet?)
PIR insulation sheets straight onto plastic
T&G over top
Laminate, with either built-in or separate underlay to finish

Does this work? I see lots of other mentions of floating floors using wood frames or battens - why?

I have one external door to contend with, what's the minimum thickness of insulation that's worth doing?

Thanks,

JB

 

[Deleted member 174758]

Please confirm (or otherwise) the robustness of my plan:

Sand or self leveller to raise low spots
Damp proof stone floor (plastic sheet?)
PIR insulation sheets straight onto plastic
T&G over top
Laminate, with either built-in or separate underlay to finish

If your original structural floor isn't too far out of level it won't be necessary to level it with screed or sand. 2 to 3mm is perfectly acceptable

The DPM should ideally be 1000 gauge Visqueen or similar, lapped up the walls, and not just any old plastic sheet

By T&G I assume you actually mean T&G 18mm chipboard (precise terminology really does matter in this instance - ask a timber merchant for T&G and you'll probably get softwood). If so, then yes with the following caveats - all joints must be glued (ideally with the manufacturer's own glue, normally a D4 PU glue) and the joints must be pulled up tight with something like ratchet straps. This will form a strong, single piece floating floor structure (the sub-floor)

Does this work? I see lots of other mentions of floating floors using wood frames or battens - why?

I think people are confusing a floating floor with something else. There is no point of floating a sub-floor onto joists, frames or battens because the floor will potentially be quite noisy - when going onto a timber structure it is normal to fix the sub-floor to the timber structure which improves structural rigidity, load bearing capacity and reduces noise (a floating sub-floor would potentially bang or thump against the framework in exactly the same way a looae floorboard does, as people moved about on it) . A laminate finished floor can be floated on top of a timber sub-floor, so perhaps the references you are looking at are confusing the sub-floor with the finished floor

I have one external door to contend with, what's the minimum thickness of insulation that's worth doing?

Insulated screeded floors I've worked on all seem to have 50 to 100mm of insulation above the DPM. I think you'll want to look at the same