Insulation type

[Zehroni]

What is the most effect flexible sound and heat insulation I can use in-between my ceiling joist, see picture

 

[phatboy]

Which do you want, sound insulation or heat insulation? You don't get to have both unless you drop the ceiling level.

And if that's another room of your house above, why would you want to heat insulate anyway?!

 

[endecotp]

Acoustic mineral wool batts between the joists.
Then if you need better thermal performance, put a layer of e.g. Kingspan over the bottom of the joists.

 

[Zehroni]

would ant loaf insulation roll of 200mm do the job
I need to insulated the two rooms, this on and the one above it as both will have under floor heating.

 

[endecotp]

would ant loaf insulation roll of 200mm do the job

It won’t be as soundproof as acoustic mineral wool.

 

[^woody^]

If you have underfloor heating, that manufacturer would specify the insulation required. Typically, you would need a reflective foil or metal tray.

 

[Zehroni]

yes there will be underfloor heating with aluminum spreader plats. I have the CAD drawing from the under floor heating but nothing mentioned about insulation in-between the joist. I understand the rigid board is the best but are not flexible. So I am thinking of 200mm loaf insulation.

 

[^woody^]

Spreader plates are to hold the pipework, not reflect the heat.

You'll end up with a hot floor and ceiling, but a cold room.

 

[Zehroni]

sorry for the confusion. this ceiling is the floor for the room above, the picture was taken when I am standing on the GF room which will have UFH and showing beneath the FF room which I will installing UFH