Insulation question

[HawkEye244]

I'm insulating a timber floor and underneath is a flat. I'm not sure what insulation to use as it's a very old house and the joists bow and twist throughout. Having looked at the insulation suitable for flooring mostly all of it comes up as rigid (the sheets that need to be cut to size), this is going to be almost impossible to fit correctly in the joists I have.

SO

I've considered either rockwool flexi slabs, or isover (loft roll), with preference to rockwool. I want to make sure though that what I buy has a reasonable impact on sound traveling because it's going to be in the region of £400 to do the whole floor.

Would anyone have any suggestions to what other insulation I can use?

I want recommendations of products that people have used personally, not a link to some insulation they have no experience with.

Thanks

P.S Even rockwool rockfloor looks like it is rigid and not flexible.

What's the right thing to do here?


P.P.S Floor is approx 150 joist depth

 

[freddiemercurystwin]

Well Crown Acoustic Roll is designed for the job, its squashy like Rockwool but denser so has better sound absorption. Here's a link: http://www.siginsulation.co.uk/Literature/crown joist roll.pdf

 

[HawkEye244]

Well Crown Acoustic Roll is designed for the job, its squashy like Rockwool but denser so has better sound absorption. Here's a link: http://www.siginsulation.co.uk/Literature/crown joist roll.pdf

Looks difficult to get hold of.

I type crown acoustic roll into google and all I get is Knaff..

But then looking at the brochure don't Knaff manufacture it? But then there are loads of alternative Knaff insulation, so confusing !

 

[freddiemercurystwin]

Yes Knauff is the manufacturer. Its a popular insulation used in building from domestic extensions to multi million pound developments throughout the land, any good merchant will be able to supply it.

 

[HawkEye244]

Thanks chap this looks like good stuff.

There's one or two local merchants that stock it.

One thing I'm still confused on is that in some pictures it's brownish looking and in that brochure it's yellow. What's that all about ?

I know they airbrush pictures, glamor models etc, but is it really necessary to do it with insulation?