Party walls noise insulation

[Terryturf1]

Ok so i asked the building control officer what insulation to put between my party walls 

Im dividing an 18m×12m portal frame barn into 3 houses 

He advised me to employ an acoustic company to advise

Surely theres some format to this . I am using cavity wall blockwork 

So what can i do other than use the acoustic slab wool insulation then maybe some special noise proofing plaster on these walls after

Help!!@

[PeterW]

If you are using cavity walls then use the heaviest block possible and also make sure every joint including the perp ends are fully mortared. Sound gets through the tiniest gap, and you need to make sure that you get mass in the walls. 

What cavity can you afford to leave ..?

[Moonshine]

Yeah, this is my bag.

 

Assuming it's 100mm cavity, put superglass or isover party wall roll in there.

 

If you want some more detailed advise send me a message with some drawings

[Ferdinand]

If the third party company will give you a guarantee on the result, then I would attach a high value to that, as getting it wrong can have a big downside.

 

Sound insulation is pretty basic, and expensive to improve afterwards I think as it is buried deeply. So if you DIY it, then have a plan B for improvement for when the test engineer sucks his teeth and goes "sorry, Guv".

 

Plan B might be, if permissible, to not cosmetically fit out the next one until you have sound tested the last one, so you can beef it up on the other side in Unit 2 without having to half-demolish the interior of Unit 1 to get it back to a point where you can do the work.

 

I think you could *maybe* get some decent advice from Building Control on this, because they always want houses that work.

 

Ferdinand 

 

Edited November 21, 2019 by Ferdinand

[ADLIan]

Assuming under English Regs Appr Doc E has masonry cavity wall and solid wall options that ‘should’ work but need testing on completion. Alternative is to look at Robust Details (RD) and follow their design details. Unfortunately this only covers new build, not conversion, so testing probably still required unless you can convince BCO otherwise.  As above detailing to avoid flanking transmission is critical as is quality of workmanship. Adding mineral wool in the cavity gives little, if any,  acoustic benefit as the acoustic performance is down to the mass of the wall and 2 decoupled leaves.

Mineral wool rolls or slabs, at least 18 kg/m3, are needed to prevent party cavity wall thermal bypass - a thermal requirement reducing the party wall u-value to zero (See Appr Doc L1). This may not be so critical with conversion work but check with your BCO. The RD view is that this measure must not degrade the acoustic performance of the wall hence they show both filled (optional) and unfilled  cavities.

[Mr Punter]

Beware of mortar on wall ties and in the cavity at the bottom.  Joint the wall properly.

 

We have done these in rendered medium density block.  Passed without issue.

[Terryturf1]

De coupled leaves ? Are you saying not to use brick ties ?

[ADLIan]

Must use 'Type A' wall ties (lighter with low dynamic stiffness) and minimal fixing density to limit transfer of sound between the 2 leaves.

+1 on mortar droppings on ties and bottom of cavity!

[Moonshine]

9 hours ago, Terryturf1 said:

De coupled leaves ? Are you saying not to use brick ties ?

 

no he is not, use resilient ties wall ties (Type A) correctly spaced (i.e. not too many of them).

 

What @Mr Punter is describing is too much mortar build up / snots on the ties will cause bridging of the cavity and reduce the acoustic performance of the wall. 

 

This is particularly of note if using insulation slabs / roll in the cavity as careless brickies can let build up happen on top of the insulation slabs / roll which causes issue.

 

Edit: if you find things like below, you want to be having a lot of words with your brickies!

 

Edited November 22, 2019 by Moonshine

[Moonshine]

18 minutes ago, ADLIan said:

mortar droppings on ties and bottom of cavity!

 

Mortar at the base of the cavity is not usually a problem on open cavities unless the is a gas/pollution membrane at the foot of the cavity (at floor level). If there isn't this in place then mortar will just drop down to the oversite level and not a big issue acoustically. The big issue acoustically comes where there is a gas/pollution membrane at the foot of the cavity and the mortar gets trapped and the brickies don't clear it out.

 

A way around this is to keep blocks out at the base of the cavity to allow cleaning of mortar droppings.

 

Edited November 22, 2019 by Moonshine

[Jenni]

I'm going through exactly this at the moment. Architect and BC both said to get advice from the company that will be doing the test. 

 

I've contacted half a dozen companies, some want to see drawings before quoting. 3 companies gave ballpark costs - all roughly same for the actual testing (just shy of £400+vat). 

Massive variety of advice cost though - from £80 to £700 depending on how much they hold your hand. 

Edited November 22, 2019 by Jenni

[Moonshine]

5 minutes ago, Jenni said:

Massive variety of advice cost though - from £80 to £700 depending on how much they hold your hand. 

 

It could be a lot cheaper than that! send me a PM if you want some advice on your drawings