zoe61

Internal Stud Walls

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Trying to decide on what products to use for the stud walls and struggling to find any definite answers anywhere. My understanding is all stud walls need some sort of insulation in them- regardless of whether there is a door opening or not, but the bathrooms need increased sound insulation for building regs.

 

Our stud walls are constructed from 100 x 50mm. Is it sufficient to use a roll product here or should I be using batts?

 

Bathrooms- should I be using batts? Again what thickness- 100mm?

 

For rooms where I think sound transfer could be bad I will be placing Soundbloc on both walls. 

 

For the ceilings we have a lot of batt type insulation that we got for free so I will be using that in the ceilings.

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Rwa45 usually my preference. 

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There is nothing in the regs that say there needs to be increased sound insulation in walls for bathrooms.

 

The regs do say for internal walls and floors the minimum acoustic specification is Rw 40 dB, but.... this does not apply, where;

  • An internal wall contains a door
  • An internal wall separates an en-suite and the associated bedroom

For a 100 x 50mm stud you can achieve Rw 40 dB with 1 x 15mm wallboard either side, with only 25mm 12 kg/m3 mineral wool in the cavity. 

 

Now this is a minimum, if you want to improve it and keep the single stud, you have three routes.

  • Increase the mass of the plaster board, e.g. 2 layers of 12.5/15mm SoundBloc
  • Increase the density and thickness of mineral wool in the cavity, e.g. 75mm of 24-48 kg/m3
  • Mount the layers of plasterboard on resilient bars for an up lift in acoustic performance.

What is you floor construction? as it is likely that as it stands it achieves the min Rw 40 dB, and additional insulation will help bring up the performance, as well as those type of improvements listed above for walls.

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Floor construction is currently 219mm deep posi-joists with 22mm eggerboard on top. 

 

If I have a 100mm cavity would I place 100mm of the RWA45 or does it only need to be partially filled?

 

If I chose to stay with mineral wool does just increasing the thickness from 25mm to 100mm have a significant effect or not really? 

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24 minutes ago, zoe61 said:

Floor construction is currently 219mm deep posi-joists with 22mm eggerboard on top. 

 

If I have a 100mm cavity would I place 100mm of the RWA45 or does it only need to be partially filled?

 

If I chose to stay with mineral wool does just increasing the thickness from 25mm to 100mm have a significant effect or not really? 

 

That floor should be fine with a min 15mm wallboard, though this can be reduced if you put insulation in the cavity.

 

There can be concerns if you fully fill the cavity with the transference of vibration via denser insulation batts to the two walls leaves given its a single stud frame. It may be better to err on the side of caution and partial fill with a small gap. Also going 75mm -> 100mm is only a marginal gain in relation to acoustics really.

 

Going from thickness 25mm - 75/100mm makes a difference, as the thicker the insulation and / or cavity, the better the comparative sound reduction performance at lower frequencies will be. Though a lightweight (timber / metal stud) is never going to be comparable to a masonry construction at low frequencies.

 

Also remember these are bare minimum, and it is advised to go above these. Also consider your internal doors, go for solid core rather than hollow. 

Edited by Moonshine
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I also prefer Rwa45, the most convenient.

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On 04/06/2019 at 12:48, Moonshine said:

The regs do say for internal walls and floors the minimum acoustic specification is Rw 40 dB, but.... this does not apply, where;

  • An internal wall contains a door
  • An internal wall separates an en-suite and the associated bedroom

 

This might be England regs?

 

In Scotland it is different and the exemption stated is:

 
Quote

 

Limitation:

This standard only applies to a wall or floor forming an apartment in a dwelling and a room in a residential building which is capable of being used for sleeping; other than:

  1. a wall between an en-suite bathroom and the apartment or room it serves

  2. a hospital

  3. a place of lawful detention.

 

 

So, unless I have missed something, you need to waste some money and speed up wrecking of the planet upgrading walls with doors in them too.

 

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On 04/06/2019 at 14:03, Moonshine said:

That floor should be fine with a min 15mm wallboard

 

My understanding is that this might not be ok because standard wallboard like Gyproc wallboard even at 15mm is only 9.8kg/m3 according to British-Gypsum's data sheet for it. The Scottish Building Standards minimum is 10kg/m3 - eg. 12.5mm Gyproc Soundbloc or Wallboard Ten.

 

Please correct me if I am wrong - it will save me loads of money.

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Our regulations ask for reasonable sound resistance to be provided between a room containing a WC and any other room AND a bedroom from any other room. Sound resistance is not required to en en-suite or to a wall containing a door.

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