100m Concrete Block vs Stud Wall Options (Staggered, Double, Metal)

[Gaf]

I imagine this has been asked a lot. I've searched here and Googled, and am finding it tricky just to get an exact answer.

 

We'll have solid concrete first floor. The first floor walls have been drawn up by our architect as stud walls with below spec:

• 75mm x 50mm
• 400 centers, with noggings.
• 50mm Isover Acoustic Partition Roll
• Resilient bars on one side of studs
• 12.5mm plasterboard
• Skim finish to sides

 

We have family with solid block walls on first floor and they swear by their sound proofing. From what I can gather, solid concrete blocks have an Rw value of 48-49. I understand this can depend on wet or batten plasterboard.

 

The docs I can find on the Isover acoustic roll only seem to give an Rw value for 25mm thickness with metal studs, specifically Rw 47, but this also includes 12.5 of Gyproc SoundBloc which isn't specified as our plasterboard. I can't locate 50mm Isover Rw data with timber studs to compare to the solid block.

 

Further, from searching this forum, a common recommendation is to go with staggered studs to improve both sound damping (walls on each side aren't 'connected') and sound proofing (sound insulation can interweave around the studs). If we go with stud walls, at a minimum are we right to get the stud walls changed to the staggered type?

 

We understand there is a likely added cost to going solid block, but the builders we're lining up to tender the work have all said that's pretty standard now and no issue for them to go solid concrete on the first floor. Is there any glaringly obvious sound proofing disadvantage to going solid block?

 

 

 

[nod]

If soundproofing is your main consideration You will get best acoustics from a stud wall You could even add a proper acoustic party wall 

50 mil stud 50 mil cavity 25 mil isover 

50 mil stud two layers of staggered soundblock 

Or 90 mil stud 50 ISO 1-2 layers of sb

As a rule anything solid like block or timber Will transfer the sound 

[Conor]

Metal all the way mate.

[Nick Laslett]

You can see the acoustic properties for metal frame stud walls in the white book. 
 

https://www.british-gypsum.com/specification/white-book-specification-selector/white-book-overview/internal-partition-systems

 

As @nod suggests 2 layers of boarding and resilient bars, can be effective if fitted correctly. Staggered I-Studs are good too. It really depends on how much you want to spend. 
 

With a block wall you can improve the acoustics by fitting metal framing with decoupling clips like IsoMax or genie clip. There are many variants. 

 

Edited November 26, 2023 by Nick Laslett

[Gaf]

@nod Soundproofing is main consideration. Initially we were thinking of heat retention with solid block but sound proofing would be a higher priority for us as we've an 18 month old and another one on the way, with their two future bedrooms sharing a stud wall as well as sharing a wall with the main bathroom that has a shower.

 

Just to make sure I have that first option you mentioned correct below?

• Soundbloc plasterboard (1 or 2 layers) on each side of the wall

• 50 mil stud that's staggered

• 50 mil cavity with 25 mil isover to allow the insulation to 'weave' between the staggered stud

@Conor From your previous posts I had a feeling you'd say that

 

@Nick Laslett Ah thanks for the steer to the white book.

 

Interesting with the decoupling clips. Wonder where the costs of this approach lands in comparison to the soundbloc with staggered studs.

[joe90]

Re sound proofing this was my only regret with my build. Stud wall between office/occasional bedroom and second bedroom, wood stud with single plasterboard each side and sound insulation between studs = poor result, likewise single plasterboard on downstairs ceiling with sound insulation above = poor result. In hindsight I would have used decoupled studs etc for the stud wall and used sound rails and double boarding fir the ceilings, hey I have 20.20 hindsight.😇

[nod]

15 minutes ago, Gaf said:

@nod Soundproofing is main consideration. Initially we were thinking of heat retention with solid block but sound proofing would be a higher priority for us as we've an 18 month old and another one on the way, with their two future bedrooms sharing a stud wall as well as sharing a wall with the main bathroom that has a shower.

 

Just to make sure I have that first option you mentioned correct below?

• Soundbloc plasterboard (1 or 2 layers) on each side of the wall

• 50 mil stud that's staggered

• 50 mil cavity with 25 mil isover to allow the insulation to 'weave' between the staggered stud

@Conor From your previous posts I had a feeling you'd say that

 

@Nick Laslett Ah thanks for the steer to the white book.

 

Interesting with the decoupling clips. Wonder where the costs of this approach lands in comparison to the soundbloc with staggered studs.

Yes the two 50 mil stud walls Double boarded (staggered) Is what I install splitting student accommodation blocks Only difference is the top layer is fire board 

It makes for a very good acoustic setup 
 

I’ve just split a unit into three with a similar setup two lots of offices and sawing machines running all day in one unit 

[Gaf]

@joe90 Literally read my mind on the ceiling sound proofing. Just posted about this in a separate post to keep things separate. Thanks for the steer about your own experience, especially as it looks like your setup, that you're not happy with, is what the architect has put into our drawings.

 

@nod So the staggered part is the plasterboard being staggered 'across' each other, so one plasterboard covers the joint where the two boards behind meet? Do you stagger the studs also to allow the isover to weave yeah?

 

Sounds like a good setup if it's working with sawing machines running all day.

[Nick Laslett]

Some good visualisation of different make-ups, here. 
 

https://www.steelconstruction.info/Acoustic_performance_of_walls

 

[joe90]

Or this. 

[nod]

18 minutes ago, Gaf said:

@joe90 Literally read my mind on the ceiling sound proofing. Just posted about this in a separate post to keep things separate. Thanks for the steer about your own experience, especially as it looks like your setup, that you're not happy with, is what the architect has put into our drawings.

 

@nod So the staggered part is the plasterboard being staggered 'across' each other, so one plasterboard covers the joint where the two boards behind meet? Do you stagger the studs also to allow the isover to weave yeah?

 

Sounds like a good setup if it's working with sawing machines running all day.

Start at one end then come back across what you have already boarded Then do the same at the other side Staring from the opposite end 

[saveasteading]

Just to say, that's all good advice.

 

You need density and decoupling.

The block provides only density. 

Also, hence 2 layers of board is better than one.

 

It does depend a bit on the type of noise, what function  is on the other side,  and whether the wall is subject to impact. A variety of construction may provide better value.

 

I've done lots of acoustic walls where it was critical, and tested. 

I've always gone with stud, whether steel of timber. They never work as well as the brochures say, so build the next level up. 

[Mike]

Worth knowing first that there are two main types of sound involved - airborne sound (often talking & music) and impact sound (e.g. opening & closing cupboards, using light switches).

 

This is the stud that I'm currently building -  2 x 70mm metal studs, 2 x 45mm hemp sound insulation, with 2 x GypsoLignum (a heavyweight plasterboard alternative) each side.

 

 

That should give a theoretical reduction of around 65db against airborne sound, and it's the board & insulation providing that.

The staggering physically separates one side of the partition from the other, and it's that which reduces impact sound transmission; resilient bars, or a full double partition are other ways of doing that.

You also want to think about the placement of power outlets & switches that are on opposite sides of the partition, to avoid them becoming a sound leakage path. They need to be at least 300mm out of alignment with each other, though 500mm or more is preferable.

 

Tweaking the floor plan can also be useful, if it's not too late. For example installing a fitted wardrobe on the opposite side of a partition to a bathroom adds very useful sound resistance that may make other measures unnecessary for that particular partition.

 

So to answer your questions:

5 hours ago, Gaf said:

at a minimum are we right to get the stud walls changed to the staggered type?

Yes, if impact sound is likely to be an issue and / or you can accommodate the modest extra width.

 

5 hours ago, Gaf said:

Is there any glaringly obvious sound proofing disadvantage to going solid block?

No, but I'd probably do it anyway, provided it was traditionally plastered. The airborne sound resistance of solid blockwork is very good and, if it's plastered medium or dense blockwork, you can easily screw anything to it anywhere. If there was a concern about impact sound transmission between certain rooms then, space permitting, I'd likely add a single sided 45mm metal stud wall on one side, set 10mm away.

 

 

[nod]

There’s often a misconception about acoustic insulation It doesn’t have to be particularly thick It’s there to stop the sound rattling around in the void 

[Iceverge]

We have 215mm block on flat wet plastered sand cement and then skim both sides between two of our bedrooms here.

 

I have never heard anything through them. 

[Mattg4321]

I’ve been thinking about this too. What about 75mm timber studwork with resilient bar and soundboard on both sides (plus 50mm insulation internally) as a budget option?