Best model acoustic insulation for studs and joists?

[markharro]

@Gus Potter @Kelvin thanks very much for this - on the basis of this advice I think I will opt for 75mm for my 90mm wall void aiming for slight airgap on each side of insulation. Gus when you say use medium density wool is this say a 45kg/m3 product? This sort of stuff - https://www.insulationexpress.co.uk/acoustic-insulation/acoustic-wall-insulation/rockwool-rwa45-50mm-acoustic-insulation-slabs-6-48m2

 

And in tips of best place to buy this stuff?

 

Kelvin, what do you use for sealing joints and gaps? Some sort of acoustic mastic or silicone?

 

Finally I am thinking of using Fermacell board on some walls so presumably a 12mm Fermacell board might give the same acoustic performance as a 15mm acoustic PB? 

[JohnMo]

13 minutes ago, markharro said:

And in tips of best place to buy this stuff?

Prices vary from supplier to supplier daily, you are best to shop around. Rockwool Flexi is pretty good also.

 

I sealed all my gaps by stuffing off cuts of rockwool into them.

 

We have 100mm studs, 70mm rockwool, no gaps, 12.5mm plasterboard either side, taped (not plastered), decent doors, with 10mm under cut, and you hear nothing going on in the house. The only exception to that is around our lounge has structural walls 200mm thick they have 2x 70mm rockwool in them.

 

Lots of overthinking going on.

[Kelvin]

https://soundproofingstore.uk/product/soundproof-acoustic-sealant-900ml-tube/
 

This stuff. I ummed and ahed about using this or just one of the many tubes of other stuff I already had. 

[crispy_wafer]

13 minutes ago, markharro said:

@Gus Potter @Kelvin thanks very much for this - on the basis of this advice I think I will opt for 75mm for my 90mm wall void aiming for slight airgap on each side of insulation. Gus when you say use medium density wool is this say a 45kg/m3 product? This sort of stuff - https://www.insulationexpress.co.uk/acoustic-insulation/acoustic-wall-insulation/rockwool-rwa45-50mm-acoustic-insulation-slabs-6-48m2

 

And in tips of best place to buy this stuff?

 

Kelvin, what do you use for sealing joints and gaps? Some sort of acoustic mastic or silicone?

 

Finally I am thinking of using Fermacell board on some walls so presumably a 12mm Fermacell board might give the same acoustic performance as a 15mm acoustic PB? 

 

Just going through this right now...  Without ringing the builders merchant the best price I've found online so far on 60mm rwa45 is 30.73 per pack delivered.

 

6 minutes ago, JohnMo said:

 

Lots of overthinking going on.

 

But this is what we SB'ers do...  trying to do the best we can without prior experiences to call upon.  and are afraid of the sucking through teeth trades when they come on site, and the 'you dont want to do it like that, you should have done it like this'...

 

11 minutes ago, JohnMo said:

70mm rockwool, no gaps

Was the 70mm stuff, acoustic roll stuff?  As that's quite a bit cheaper for coverage than slabs

 

[saveasteading]

1 hour ago, markharro said:

 tips of best place to buy this stuff?

Our best price by far came from the local, independent BM. You would have expected the national specialist* to have done better but no.

  Ditto online suppliers.

If you want a lot, then it may be coming direct from the factory, whoever the intermediary.

 

* Who once told me they couldn't match their Oxfordshire price to us for another job in Kent,  ( a lorryload direct from S Wales) because they didn't need to. Actually they did need to  because I got it elsewhere.

 

Choose the product. Shop around. Consider changing product. Shop around. Ask if it makes any difference to have it all at once or in stages. It does not store well outdoors.

 

[JohnMo]

1 hour ago, crispy_wafer said:

Was the 70mm stuff, acoustic roll stuff?  As that's quite a bit cheaper for coverage than slabs

Rockwool Flexi slabs, stiff with one edge soft to fill any gaps

 

[saveasteading]

30 minutes ago, JohnMo said:

to fill any gaps

Important. Gaps are bad for thermal and sound insulation.

Better a poorer quilt with no gaps than the densest fitting poorly.

[markharro]

On 16/10/2023 at 09:48, Kelvin said:

This stuff. I ummed and ahed about using this or just one of the many tubes of other stuff I already had. 

Thanks @Kelvin would you happen to know if these tube sizes are compatible with the Makita powered mastic gun I have....this one - https://www.screwfix.com/p/makita-dgc180zbk-18v-li-ion-lxt-cordless-caulking-gun-bare/861xj#product_additional_details_container ?

 

Looks like maybe not!

[markharro]

This looks like a better option? https://www.amazon.co.uk/Everbuild-AC50-Acoustic-Sealant-Adhesive/dp/B006SV7PPS/ref=asc_df_B006SV7PPS/?tag=googshopuk-21&linkCode=df0&hvadid=309785471682&hvpos=&hvnetw=g&hvrand=1442873038680153081&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9046891&hvtargid=pla-696901975666&psc=1

 

About £1 per tube as standard size so should fit in my gun I think?

[Kelvin]

I dunno. I just use a manual gun. Quick enough. 

[markharro]

ANother question on sound insulation. We have quite a few sheets of EPS100 and 300 insulation that was used for the tray for our slab left over. They are 100mm thick. WOuld these work specifically as sound insulation and if so how would they perform compared to say a 45 density rockwool batt?

[Thorfun]

29 minutes ago, markharro said:

ANother question on sound insulation. We have quite a few sheets of EPS100 and 300 insulation that was used for the tray for our slab left over. They are 100mm thick. WOuld these work specifically as sound insulation and if so how would they perform compared to say a 45 density rockwool batt?

 

might be worth a read as it's been asked before

 

 

[markharro]

Thanks - this indeed was very helpful - looks like the answer is a resounding don't bother. Hopefully someone might be interested in buying my surplus EPS now - currently advertised on the Marketplace