Insulating 140mm CLS internal stud walls

[Nick1c]

I am almost at the point of doing this & have been reading this section of the forum for tips but still have some questions. 
Rockwool have 2 products which look suitable - RWA45 & flexi, there doesn’t seem to be any great price difference - which is most suitable/ nicer to install? Are there better/ more cost effective alternatives?

What is the most sensible thickness to use? The gf has 3 beds in a line, with a built in wardrobe separating each one, the floors are separated by a160mm slab of CLT with a suspended ceiling for services & the upstairs is largely an open plan room with a ‘snug’ next to it (above our bedroom). Full fill would £££, but is there significant gains in using over 50mm? 

[Russell griffiths]

Knauf omni fit, just used this in our roof, was a pleasure to fit, so snuggly the bloody dogs tore a pack apart and made a bed. 

 

What is the difference in cost between 50 and 100 cannot be much, if you skimp on the thickness you might regret it later, you will never be able to put more in. 

 

I personally would be worried about a bedroom that backs onto another and would do as much as I could to keep the noise down. 

[nod]

It depend weather are insulating for sound or heat loss 

The vast amount of job we do use 25 mil acoustic in ceiling's and walls to simply stop the sound bouncing around in the void 

[Thedreamer]

We used frametherm 35, in the walls, but I would probably go for frametherm 32 if I could do it again.

[Russdl]

I’m using RWA45 (50mm). I can’t comment on how well it works because the house isn’t finished and when it is finished I’ll never know what it would have been like without. We’re using resilient bars in lots of areas as well. 

 

Currently, in a door-less house it’s really difficult to get the attention of someone upstairs, they can’t hear you.

 

Not one of the Rockwool batts have fitted the space available without cutting but they are very easy to cut with an old saw. I cut them 5-10mm oversize and they squeeze in a treat and stay there. 

[Nick1c]

@Russdl are you doing a new build? If so what are the stud spacing, ours are a pretty accurate 600, I had assumed the batts would be a pressure fit with no cutting!

The cost seems to be proportional to the volume, has anyone used different thicknesses & can give a real life opinion of the difference?

Once the batts are in we will be left with the holes chopped out for the MVHR duct - are they worth foaming? I assume there will be some noise transfer via the duct voids. 
Any suggestions of a well priced source that will deliver in these times would be gratefully received. 

[Russdl]

@Nick1c yep, it's a new build. MBC timber frame. The studs are theoretically 600 centres but we haven't found many that are and as the batts are 600mm wide they've pretty much all needed cutting. Apart from the time element it's been no big deal cutting them.

 

I've been surrounding the MVHR ducts with the Rockwool. There have been lots of little bits left over, perfect for stuffing in to all the little nooks and crannies.

[Bored Shopper]

We're obsessed with sound insulation (currently living in a rented house where you can easily keep conversation between GF and FF without raising your voice with doors closed, such a nightmare). We're stuffing Rockwool Flexi 140 wherever we can in internal stud walls and in the GF ceiling, and in a currently door-less house you can definitely hear the difference. It soaks up sound and really muffles it. Quite pleased. Also made a point of surrounding utility area with it to keep the noise from boilers / washing machine / tumble dryers down.

[Cpd]

27 minutes ago, Bored Shopper said:

We're obsessed with sound insulation

Yup... I went a bit bonkers when I did my floor between upstairs and downstairs....... x3 layers of acoustic plaster board x 3 diffrent layers of acoustic rockwool..... etc etc....... ongoing..... 

[Bored Shopper]

15 hours ago, Cpd said:

Yup... I went a bit bonkers when I did my floor between upstairs and downstairs....... x3 layers of acoustic plaster board x 3 diffrent layers of acoustic rockwool..... etc etc....... ongoing..... 

did you achieve the result you wanted? is it quiet?

[Cpd]

8 hours ago, Bored Shopper said:

did you achieve the result you wanted? is it quiet?

 

23 hours ago, Cpd said:

ongoing..... 

 

still got the stair hole open with no stairs or doors..... the project ground to a standstill when I became ill a few years ago and  even though I am back on the tools now I have become distracted by other projects That I started during my “time out” so to speak.