Insulation for external stud wall - cheap & flexible

[DiscoDroid]

For various reasons I’ve built a ‘double’ gable end stud wall from timber. Post from 2 Mar 2024 says why I came to double up.

The inner stud I’ll fill with cellotex to get the required U-value and provide something of a vapour barrier.

This leaves the outer stud and cavity gap – a great opportunity to add some extra insulation!

I’d like something that’s flexible, relatively cheap and, critically, rated to sit behind OSB on an external tiled wall. U-value isn’t a big driver for me – it’s all additional to the requirements. Can anyone suggest a good product for this?

I was thinking about standard loft insulation (example) but don't think it's rated to be on an external wall.

Thanks in advance

 

[^woody^]

Has that design been approved by anyone?

Any quilt will do. You may need Rockwool or similar for the sound insulation. There should be no air voids within the frame

And you don't seem to have a ventilated cavity between the frame and the cladding, nor a cavity tray where the frame meets the masonry.

What fire stopping will there be within the cavity?