Insulating suspended timber floor - PIR boards vs multi-layer quilt?

[Heyho74]

I have to insulate our lounge floor (4x5m) once the rest of the room has been fiinshed.

It's freezing in there, as its bare boards (and that's how it's staying I am told), with no insulation. I was originally going to cut PIR boards (50 or 70mm) to sit on battens between the joists, but a chippy mate of mine reminded me of the thermaquilt multi-layer blanket insulation.

Just wanted a sanity check really - the quilt is winning in my mind at the moment, as it's a little cheaper, and would be a whole lot easier to install - straight over the joists with no messy cutting, and it would (to a degree vs the PIR) negate the thermal bridging I would still get using boards. The insulation values are fairly close.

Anything I'm missing?

 

[endecotp]

Why not rockwool?

The numbers for “multifoil” insulation are controversial.

 

[JohnD]

mineral wool quilt is IMO better, because you can squash it to fit between the joists even if they are not straight or the gap is uneven. It will block draughts which are the main source of cold in a wooden floor (there is no convection, and little radiation or conduction loss)

Pack it especially well round the edges of the room, where draughts and dirt blow up under the skirting.

You can cut it with a breadknife or big scissors, and shove scraps in any gaps.

Use the stuff treated with Ecose to prevent shedding irritant dust or fibres. It is brown, not yellow. It even muffles noise a bit.

In case of fire it does not emit poisonous smoke, and does not burn or drip molten or flaming plastic. We know that the insulation boards do.

 

[Heyho74]

Thank you gentlemen for your responses. Having done a bit more reading, I understand now that even if the claims made for the multi layer quilt were accurate, it's not the ideal product for what I'm doing.

With regards to the rock wool, would the slabs be suitable or would I be better off using rolls?

 

[Notch7]

or this stuff:

https://www.roofingsuperstore.co.uk...OFOgXpa9qVuK4Y32PdQfM2jkUnuELHF4aAucqEALw_wcB

not sure it would be self supporting though.

mineral wool quilt can be kept in place with netting -plastic stuff from a garden centre