Acoustic insulation thickness and wiring in studs

[junglejim]

Possibly a can of worms question but my internal studs are 89mm deep and we’re looking to use Rockwool rwa45 slabs. First question is thickness: local merchant stocks 50 and 100mm so was going to go 100 but now wondering how best to manage wiring ie to sockets and light switches within that?

 

 Many thanks

[Nickfromwales]

27 minutes ago, junglejim said:

Possibly a can of worms question but my internal studs are 89mm deep and we’re looking to use Rockwool rwa45 slabs. First question is thickness: local merchant stocks 50 and 100mm so was going to go 100 but now wondering how best to manage wiring ie to sockets and light switches within that?

 

 Many thanks

Don’t go 100mm as it will stop the boards going on!

 

Choose a better supplier and use 75mm with the gap then used for services. 

[Oz07]

50 I'd go with. Plenty room for services, I think the air gap actually helps acoustic performance and it will be cheaper too

[Thorfun]

We used 50mm and I think it was fine acoustically. 

 

it’s amazing how small 39mm space is for running cables (14.5mm either side of the insulation) depending on the size of the cable you’re not left with much before the boards. So can’t imagine how tight 75mm will be. 

[JohnMo]

50mm in the centre of the studs. The air gap make the whole wall perform better from noise perspective. And the wiring has somewhere to go

[Super_Paulie]

i used 50mm as the 75mm you can only get from insulation merchants really in bulk. Centre of the stud, plenty of room for pipe or cable drops. Its great stuff like has to be said, i love working with it in comparison to any other type of insulation. Cut slightly oversize with an old bread knife, whack it in and its self supporting. Easy to cut around boxes or reduce its thickness around services. It works a treat as well it really does.

[Nickfromwales]

5 hours ago, junglejim said:

Possibly a can of worms question but my internal studs are 89mm deep and we’re looking to use Rockwool rwa45 slabs. First question is thickness: local merchant stocks 50 and 100mm so was going to go 100 but now wondering how best to manage wiring ie to sockets and light switches within that?

 

 Many thanks

Don’t go 100mm as it will stop the boards going on!

 

Choose a better supplier and use 75mm with the gap then used for services. 

[WannabeBob]

We used 75mm rw3 in ours. not sure what the rules are but I can share who supplied them if you DM me (i have no affiliation with them other than buying far too much insulation from them!)

Edited 6 hours ago by WannabeBob

[ToughButterCup]

When someone - anyone at all - finds acoustic insulation that works, please send me a postcard.  You can still hear flies fart in our  bedroom when we're outside. 

 

I propose swapping the aphorism Money for old Rope to Money for Shite Acoustic Insulation.

[junglejim]

5 hours ago, JohnMo said:

50mm in the centre of the studs. The air gap make the whole wall perform better from noise perspective. And the wiring has somewhere to go

Thanks John. That’s interesting. I was pushing the insulation right up to one face and running the electrics behind where electrics are only on one side. I’m wondering how easy the slab will stay in position if it’s in the Centre.

[junglejim]

2 hours ago, Nickfromwales said:

Don’t go 100mm as it will stop the boards going on!

 

Choose a better supplier and use 75mm with the gap then used for services. 

Thanks Nick. I assumed the 100mm would just compress slightly which i don’t think would affect acoustic performance too much?

[Nickfromwales]

8 minutes ago, junglejim said:

Thanks Nick. I assumed the 100mm would just compress slightly which i don’t think would affect acoustic performance too much?

Nope. It’ll fight your plasterboards until the death. 
 

Screws will wind in and pull through the boards, as they won’t be tight against the studs. 
 

Seriously, do not use 100mm, persevere and get 75mm.
 

 

[JohnMo]

48 minutes ago, junglejim said:

I’m wondering how easy the slab will stay in position if it’s in the Centre.

We used Rockwool Flexi and it stays put very well. Just make a slightly interference fit.

[Oz07]

The rwa 50mm is good. I've used soundbloc both sides with it too. I think  the minimum for the regs in bedrooms was soundbloc ea side and 25mm acoustic wool. Even that holds itself in well if board one side first then fit up against. 

[junglejim]

2 hours ago, Nickfromwales said:

Nope. It’ll fight your plasterboards until the death. 
 

Screws will wind in and pull through the boards, as they won’t be tight against the studs. 
 

Seriously, do not use 100mm, persevere and get 75mm.
 

 

Thanks Nick that picture’s really useful too 👍