Rockwool density

Hi all, I was wondering how much rockwool density affects sound isolation. What do you think will be better for sound isolation ? Rockwool 60mm 40kg/m3 or rockwool 40mm 70kg/m3 ? Both used in same kind of solution wich consist on: Steel studs decoupled from the existing walls then rockwool in between and then 13mm gypsum board, membrane 15mm Gypsum board Thanks in advance. Best Regards.

I may be wrong (and a more knowledgable member of this board may correct me), but I believe the insulation between the studs does not need to be dense. I think the lighter stuff is OK for that purpose. I think the more dense insulation is usually used for sound control in a room (to deaden down the reverb reflections), not so much for sound isolation between rooms.

and then 13mm gypsum board, membrane 15mm Gypsum board

Forget the 13mm drywall, and go with 2 layers of 16mm instead. The slight benefit you might get from dissimilar materials is outweighed by the advantage of the extra mass. What do you mean by "membrane"? Are you talking about some kind of mass loaded vinyl, or some kind of constrained damping layer? Or something else? - Stuart -

Thanks Both for the early replies Membrane Description: Bituminous sheets modified to obtain higher acoustic performance. Its high density and plasticity allow to use them as substitute for lead sheets, providing higher deadening of low-frequency noise produced by resonance between laminated plaster panels. Regarding the use of 16mm boards i have a friend who have access to the lab where most manufacturers make tests for their products and it seems that 13 and 15 combination is the best one. Thanks a lot. Best Regards.

Well, if you don't want to listen to advice, then why are you here?

Hi Soundman, I don´t understand why are you being so rude, as i think i have been polite since the beginning. I´m here to discuss and listen and after that get my own conlusions with the help of others knowledge. Anyway i have asked about density of rockwool not about gypsum size althought i will hear and consider anything you say. Thanks. Best Regards.

rav wrote:

I was wondering how much rockwool density affects sound isolation.

For music isoaltion, lighter is better. Read this report and pay attention to both the TL curves AND the subjective criteria used to judge the materials. Double 5/8" is better for exactly the reasons Stuart has written. Andre

Thanks a lot Avare, That´s exactly what i was looking for. Best.

Hey guys, not sure if I'm reading this correctly but are you saying NOT to use rockwool as the preferred insulation in your walls leafs? Using it instead for sound/acoustic control within the rooms when completed? For some reason i had always thought that rockwool is what was used as "the" insulation prior to putting up your gyprock/drywall.

qiktune wrote:

Hey guys, not sure if I'm reading this correctly but are you saying NOT to use rockwool as the preferred insulation in your walls leafs? Using it instead for sound/acoustic control within the rooms when completed?

No. Rockwool is a trademarked name. It is the same as specifying a guitar as a Fender or a piano as a Yamaha. Both companies sell products from the beginner to world class professional standard. Density and to a lesser degree related the material compostition is what is important in the properties that we can gather on the insulation used in partitions. Andre

Thanks for the quick reply AVare.....apologies for my own "density" but still trying to understand. Re the comment "For music isolation, lighter is better..." If I were to instead of using "rockwool" use Tontine Acoustisorb ( in my case Acoustisorb2 ) in my wall leafs would that not be quite ok? Once the rooms are built I could then use rockwool for bass traps/treatments etc. Here's a link to the product I'm referring to http://www.spec-net.com.au/tontine/acoustic/acous4.htm

If I were to instead of using "rockwool" use Tontine Acoustisorb ( in my case Acoustisorb2 ) in my wall leafs would that not be quite ok?

Well, comparing the specs for that stuff with "Rock Wool" brand mineral wool products, the 4" thickness of "Tontine" is roughly the same as the 3" thickness of RHT40 3pcf, and 4" of RHT40 is way superior. 4" "Tontine" is also similar to 4" 703. So I think I'd go with ordinary 3pcf mineral wool. It's probably much cheaper, too. - Stuart -

Soundman2020 wrote:

So I think I'd go with ordinary 3pcf mineral wool. It's probably much cheaper, too.

+1. :mrgreen: Succinctly, Andre