Insulation between floors in stud walls

[chriselevate]

So, I’ve previously used Rockwool PROROX SL930 (RW3) (60kg per m3) high density acoustic mineral wool in a ceiling. It’s expensive and blocks out noise. Would you suggest using the same in all ceilings or something different? I want to insulate them now I’m having new joists and there was previously no insulation.

How about 4 and 3 inch stud walls? Do they need insulating too? A builder said to not bothers as it “gets in the way” when running cables and plumbing.

Would you suggest 12.5mm acoustic dB board on stud walls to reduced sound travel?

Thanks for your help and advice as always.

 

[foxhole]

Depends on your logistics, my cables and pipework were all in place before I added the last plasterboard walling allowing me to insulate easily.

 

[endecotp]

Building regs require a minimal level of soundproofing of stud walls in new buildings.
You can either (a) put two layers of PB on each side, with a min 75mm gap, or (b) single layers of PB each side, min 75mm gap, and 25mm of regular mineral wool.
Your work may or may not need to comply with that, but even so it’s a useful guide as to what is good practice. Personally I’d consider it a minimum level.

 

[chriselevate]

Thanks guys. I think I'll go with 12.5mm DB board onto the studwork. For option (b) what 25mm regular mineral would you recommend? I'm tempted to go thicker too.
Thanks

 

[endecotp]

For option (b) what 25mm regular mineral would you recommend? I'm tempted to go thicker too.

To meet regs I think it has to be 10 kg per cubic meter - which is any bog-standard mineral wool. In choosing, handling properties (i.e. is it scratchy?) and cost are the main issues.

Personally I’d fit more, better material. But acoustic mineral wool is more expensive. How important is this to you? I’ve recently built something with wood fibre insulation batts, which give the impression of being good acoustically. Unfortunately I won’t know how good the results are until I have doors on, which might be a while yet!