# Forum Home Renovation General Odds & Sods  Help! Builder installed ceiling batts in my external walls

## Basilratbrush

We agreed on and I was very adamant that I wanted acoustic batts (Knauf sound-shield acoustic or Bradford soundcheck) but when I arrived back home, he said he ordered wrong batts and installed r4 ceiling batts throughout the entire house both internal and external walls. I'm so upset because we live right on top of a seriously busy highway and the reason we are ripping out all the walls ( previously fibro) and insulating and recladding is purely to reduce the noise. 
Its too late to change it now h has already sarked and started cladding and I have been told that its 5-6 weeks to order in soundcheck from every company I called today which we cant afford do. The builder said the sound proof batts are ll clever marketing and they are no better than R4 ceiling batts when placed in walls but everything I read says they are not as good at blocking noise due to lower density. Anyone know if he is right and I'm just falling for the marketing? I feel like i'm getting jibbed! esp because I was quoted for a house full of sound-check and he is trying to say the price for ceiling batts is actually more expensive...

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## METRIX

Depending on what R value you were quoted, but like for like R value ceiling vs wall sound batts the R4 Knauf ceiling bats are half the price of R4 Knauf wall soundshield, I wouldn't be paying extra to get less 
Se below links, look at the price per m2  https://pricewiseinsulation.com.au/p...ulation-batts/  https://pricewiseinsulation.com.au/p...ulation-batts/

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## intertd6

How thick are the R4 batts? I don't know of any normal insulation over R1.5 ~ 2.0 that will fit in a 90mm wall cavity, I'd imagine an R4 batt will bulge the wall linings if they are plasterboard.
inter

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## phild01

Be interesting to know what other soundproofing measures you are taking because if it is just batts then I doubt you will notice much sound reduction with either batt.

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## phild01

> How thick are the R4 batts? I don't know of any normal insulation over R1.5 ~ 2.0 that will fit in a 90mm wall cavity, I'd imagine an R4 batt will bulge the wall linings if they are plasterboard.
> inter

   Agree.

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## Basilratbrush

My thoughts exactly. Do you know if there reallty is much difference in noise reduction though between there R4 ceiling and r2.5 soundproof ones? the money factor is annoyinvg but its more the fact we haver gone to all the trouble and expense of moving out of our home to try and make it sound proof and It will all be for nothing

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## Basilratbrush

195 thick, R4.0

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## Basilratbrush

Double glazed windows, new flooring, full house insulation, removed any old wall vents, built 1.8 m double brick wall out front and side of house, sealed any gaps and replaced all skirtings, plantation shutters and new solid wood front and back doors, all doors and windows sealed with rubber seals

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## phild01

Did you opt for 16mm plasterboard. The solid doors, DG windows and and brick wall should make a lot of difference. Can you see any of the wall insulation used.

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## r3nov8or

> 195 thick, R4.0

  He may have even ripped them in half to fit comfortably!

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## havabeer

Arent you meant to not compress the batts for them to work properly.  
I too dont think you would notive much differnce with the different batts, i would 100% be checking the price difference though.

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## Basilratbrush

yes, we got him to install the thicker plaster board. I didn't see them put it in at the time  but can see behind the sarking and the packaging was r4 knauf ceiling bats and all the internal walls  were done in 2.0 standard batts (sorry should have mentioned that) and the ceiling was all done in 4.0 which I'm obviously not concerned about. Is there really any perceivable difference between what we now have and the actual soundscreen batts?

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## Basilratbrush

If compressed it affects the thermal rating but since were already at double the rec thermal with R4 thats not going to be an issue. For me its always been about the noise reduction factor.
From what I can see they wont be compressed anyway, they actually fit pretty well into exterior cavity and don't bulge out at all. when i held the 2.0 and 4.0 bats side by side, they looked exactly the same, no real difference in thickness anyway.

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## John2b

It seems like neither Knauf or Bradford are willing to give actual comparative acoustic performance data, so it isn't possible to see if their 'acoustic' products actually outperform the same weight per square metre of ordinary insulation of the same type. As far as I recall from when I worked with acoustic consulting engineers, weight per area is about the main criteria for acoustic performance. As the builder has used R4 in place of R2.5 you might even be better off but again I couldn't find comparative density data either. Compressing the R4 to fit where R2.5 is meant to go will slightly degrade its thermal performance from R4, but likely improve its acoustic performance because of the higher density. 
What is important for acoustic performance is that the product is installed in accordance with instructions to ensure the integrity of insulation and eliminate flanking paths where sound energy can bypass the insulation. Ironically following installation instructions properly is also important for getting the best thermal performance.

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## phild01

> when i held the 2.0 and 4.0 bats side by side, they looked exactly the same, no real difference in thickness anyway.

  Can you be so sure they both aren't 2.0! Is this unopened packaging.

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## Sir Stinkalot

It is my understanding that the acoustic batts are of a higher density, which increases the ability to reduce sound transmission. When I have done work with acoustic engineers, they specify by density as that is where the improved performance is, not the R rating which is thermal. Unfortunately finding the density of these products in the residential market is difficult as its not readily available, especially for the non-acoustic versions of their products (such as general wall and ceiling insulation). As an example the Knauf sound-shield acoustic is 17kg/m3 for the R2 (75mm) ($ 6.57 p/m2 inc. GST) and Bradford soundscreen is 25.7kg/m3 for the R2 70mm thick ($ 9.77 p/m2 inc. GST). Prices from the link provided by Metrix as it has easy to find information and comparisons. 
There are still many unknowns, how accurately did you specify your requirements, or was it vague? I simply ask this as even in the example above regarding the cost different between Knauf and Soundscreen, its not only cost but performance differences.  
At the end of the day however he has not installed what was agreed, and the issues associated with rectification (time) are not something you can accept. As that is the case you will need to live with what was put in. As for cost, again difficult without knowing what scope and specifications were agreed upon, however I suspect that the R4 ceiling batts would be more expensive than the R2 wall batts - but I cant see how he would have been able to get the 195mm ceiling batts in a 90mm cavity wall, so its likely they have been ripped in half. If he did manage to compress the 195mm into a 90mm cavity wall, it will reduce the thermal performance of the batt, and potentially be putting pressure on either the sarking or the plasterboard. 
I did hear word around the office the other day that insulation is in shortage at the moment, so perhaps that part of what you have been told is true. As for the rest, I think you are being sold spin unfortunately on many fronts. 
Looks like John had similar thoughts - I just took longer to type mine  :Smilie:

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## joynz

> We agreed on and I was very adamant that I wanted acoustic batts (Knauf sound-shield acoustic or Bradford soundcheck) but when I arrived back home, he said he ordered wrong batts and installed r4 ceiling batts throughout the entire house both internal and external walls. I'm so upset because we live right on top of a seriously busy highway and the reason we are ripping out all the walls ( previously fibro) and insulating and recladding is purely to reduce the noise. 
> Its too late to change it now h has already sarked and started cladding and I have been told that its 5-6 weeks to order in soundcheck from every company I called today which we cant afford do. The builder said the sound proof batts are ll clever marketing and they are no better than R4 ceiling batts when placed in walls but everything I read says they are not as good at blocking noise due to lower density. Anyone know if he is right and I'm just falling for the marketing? I feel like i'm getting jibbed! esp because I was quoted for a house full of sound-check and he is trying to say the price for ceiling batts is actually more expensive...

  I insulated my walls with Bradford Soundscreen. They are excellent and heavier/denser than the normal 87mm deep wall batts.  And they seem denser than the sound batts from Knauf too.  The 87mm (R2.5) is all that fits in a standard wall.  If the builder has used R4 they have compressed them - which is completely against the installation requirements - quite apart from not using sound batts!  
Sound  batts are different from regular batts - much denser and heavier. 
Get the batts replaced.  It doesn’t matter if the sarking is already installed - it’s easy to remove and replace.  I would also inspect any insulation once installed because installers often do a terrible job and you need it to be friction fitted with no gaps.   
The builder should be sorting this out! 
Also, if you have specified resilient mounts for the plasterboard, green glue, the super heavy acoustic vinyl  etc for sound control -  make sure you are getting them.  
If you cave now, you will be kicking yourself for years to come. It’s worth the wait - even if it takes longer.  I would be getting a private inspector (or sound engineer)  to double check the work or at least visually check it myself. 
If do you decide to accept this stuff up, don’t pay for any of the wall insulation or labour.

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## joynz

In response to a couple of posters wondering if Soundscreen makes a difference, here is what Bradford says 
As a baseline, the Rw rating of a standard internalwall (10mm standard plasterboard on each side of a 90mm stud without acoustic insulation) is Rw28. The addition of Bradford SoundScreen into a standard internal wall can increase the Rw rating by six points, which halves the perceived volume of sound passing through it.  I also I found another Bradford diagram which compares types of insulation and also other sound reducing measures.   Attachment 130161

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## John2b

Thanks joynz, I did see that brochure. Unfortunately there is no "apple for apple" comparison and the units are not specified, so no meaningful comparative data is provided. The two claims in the brochure amount to that doing a lot with Soundscreen is better than doing not as much with Gold Batts; and that doing something with Soundscreen is better than doing nothing. Then there is a nebulous claim about reducing perceived sound by half; nebulous because there is a lot of argument in scientific circles what "by half" actually means in decibels, and in fact it is very much dependant on the noise source, the environment and the listener. 
As far as I know the best thermal insulation with maximum sound reduction for a given thickness is Polymax HD which are cross-linked polyester fibre batts that were developed by a couple of engineers who worked for Tontine (the largest manufacturer of industrial noise reduction insulation in Australia) but couldn't get Tontine to develop the concept, so as I understand they left and set up Martini Industries to make Polymax. If I remember correctly Tontine eventually licensed the technology from Martini to make there own version, and Martini ended up being bought by Bradford. 
Soundscreen is not the same as Polymax, but a high density version of Gold Batts. The higher density puts more weight of fibre into a given thickness, but the extra weight can also be achieved by choosing a higher R value of standard insulation. 
By contrast Polymax HD is an acrylic fibre batt (made from recycled PET drink bottles) and is not compressible because of the cross-linked fibres that are the secret to its increased performance over normal fibre batts. It is also non-allergenic, does not shed fibres, does not outgas, does not absorb moisture and is self-extinguishing. Unfortunately even though it feels soft it is difficult to cut, needing a hot-wire cutter or circular saw.

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## joynz

Hi John2b 
Interesting info. 
The Bradford website indicates that polymax is slightly less thermally efficient compared to thickness than Soundscreen.  
Unfortunately, I can’t see any information about the sound performance of Polymax on the website.

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## manofaus

Would getting the builder to add another layer of plasterboard help?

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## Basilratbrush

Yes, all the packaging is still here. Day one I got home snd it was all marked Knauf R4.0 ceiling insulation  and day two he bought it on the day from hardware store and it was knauf 2.5 wall and ceiling insulation rolls. I was able to open both packs and side by side tvey look no different in colour, thickness or density but maybe it’s one of those things where it’s all in the actual material and you can’t tell visually? 
that aside though, I’m not too worried about thickness. I really wanted tve round screen batts due to the density. I believe they are twice as heavy/dense as regular insulation. Will be interesting to see if it makes any difference to the sound but since I’ve no option but to go with it now I guess we will never know (I think that’s actually the worst thing because I’ll always wonder)

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## Basilratbrush

All the cornices are already installed abd I think it would look odd at this point  :Frown: 
the house will be externally clad in fiber cement boards so hopefully that will add a further layer of noise reduction and seal up any remaining air gaps.

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## Basilratbrush

Thank you for this

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## joynz

> Yes, all the packaging is still here. Day one I got home snd it was all marked Knauf R4.0 ceiling insulation  and day two he bought it on the day from hardware store and it was knauf 2.5 wall and ceiling insulation rolls. I was able to open both packs and side by side tvey look no different in colour, thickness or density but maybe it’s one of those things where it’s all in the actual material and you can’t tell visually? 
> that aside though, I’m not too worried about thickness. I really wanted tve round screen batts due to the density. I believe they are twice as heavy/dense as regular insulation. Will be interesting to see if it makes any difference to the sound but since I’ve no option but to go with it now I guess we will never know (I think that’s actually the worst thing because I’ll always wonder)

  In your first post you wrote:
’We agreed on and I was very adamant that I wanted acoustic batts (Knauf sound-shield acoustic or Bradford soundcheck) but when I arrived back home, he said he ordered wrong batts and installed r4 ceiling batts throughout the entire house both internal and external walls.’ 
But from the comment above it sounds like you actually have R2.5 batts in the walls not R4. 
Anyway, it sounds like you are now somewhat OK with this situation. I definitely wouldn’t be - especially if I had specified sound batts! 
Are you getting a refund on the cost difference, or even the whole cost - since they’re the wrong batts?

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## Basilratbrush

We agreed on knauf sound screen batts in 2.5 originally not standard batts in 2.0 or 4.0 but the issue is not thickness, the issue is we got standard batts and not the soundproofing batts. No, definitely not ok with the situation, but I’m now in a position where he’s not going to take it out and even if he did, we’re living in a house with no walls fir 6 weeks with two kids. The cost of temporary accomadation and tve timesaver now lost isn’t worth it so even though I’m not good with any of this I don’t have another option.
I wrote 2.5 by mistake above, the internal walls are definitely 2.0 (wall and ceiling) which I have no issue with to be honest even though that’s not what I asked for. The external walls are all  4.0 ceiling batts and given we live on top of one of the busiest roads in Sydney I wanted the best soundproof insulation we could buy, I doubt ceiling batts are going go to cut it.

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## phild01

> I was able to open both packs and side by side tvey look no different in colour, thickness or density but maybe it’s one of those things where it’s all in the actual material and you can’t tell visually?

  The R4 is 195mm thick, the R2 (not 2.5) are 90mm thick. Don't understand why you are not seeing the difference!  *Earthwool R4.0 195mm x 430mm x 1160mm 8.98m² Insulation Ceiling Batt - Pack of 18*  *Earthwool R2.0 90mm x 430mm x 1160mm 15.96m² Insulation Wall Batt - Pack of 32 * https://www.bunnings.com.au/products...sulation-batts

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## pharmaboy2

There are plenty of sound proofing forums that have done this sort of testing - by and large, acoustic is of marginal utility, and in fact its very common for a studio builder to use ceiling insulation and compress it into a 90mm wall and get superior effect than thinner acoustic batts. 
Thats also backed up by the official info posted above - 1db is negligble and not of a concern.  Of the acoustic batts i feel the only one worth  chasing up is actual rockwool - though much more expensive these days and rarer - its just std insulation now thats just denser, which is exactly what you get when you put ceiling thickness in a wall and then compress it a bit. 
If you have an external wall is particularly a problem (or room that you want to make a quiet room) - a second layer of plasterboard with green glue between the sandwich is remarkably superior to all the usual solutions, especially for lower frequency damping (without going concrete) 
Sound reduction efforts in the australian construction industry are appallingly poor performing in residential - people recommending small gap double glazing have no understanding of what the problem is, with most window manufacturers just using some "äcoustic" labelled product and stuck in with the same same technique. 
probably one of the biggest advantages of soundscreen products is that when installed in a wall from floor to ceiling, they dont sag and leave a gap over time (which std 1.5 does).  ceiling spec will not sag because its pushing against the inner and outer cladding.  The only real downside of the stuffing R4 into a 90mm wall, is that the material will bridge from inside to outside  wall which could conceivably produce a  condensation issue in the wall

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## joynz

> We agreed on knauf sound screen batts in 2.5 originally not standard batts in 2.0 or 4.0 but the issue is not thickness, the issue is we got standard batts and not the soundproofing batts. No, definitely not ok with the situation, but I’m now in a position where he’s not going to take it out and even if he did, we’re living in a house with no walls fir 6 weeks with two kids. The cost of temporary accomadation and tve timesaver now lost isn’t worth it so even though I’m not good with any of this I don’t have another option.
> I wrote 2.5 by mistake above, the internal walls are definitely 2.0 (wall and ceiling) which I have no issue with to be honest even though that’s not what I asked for. The external walls are all  4.0 ceiling batts and given we live on top of one of the busiest roads in Sydney I wanted the best soundproof insulation we could buy, I doubt ceiling batts are going go to cut it.

  Have you considered that the builder could claim on his insurance for the cost of your accommodation?  Even though he might not want to! 
If Soundscreen batts were specified in your contract you can hold him to it. 
I suggest you contact fair trading in your state.

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## phild01

> If you have an external wall is particularly a problem (or room that you want to make a quiet room) - a second layer of plasterboard with green glue between the sandwich is remarkably superior to all the usual solutions, especially for lower frequency damping (without going concrete)

  I did a wall with green glue and16mm plasterboard and felt underwhelmed not noticing any significant difference. Admittedly all I could do was put my ear to the wall to discount the noise from other areas.

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## pharmaboy2

> I did a wall with green glue and16mm plasterboard and felt underwhelmed not noticing any significant difference. Admittedly all I could do was put my ear to the wall to discount the noise from other areas.

  yes flanking is an enormous problem and measuring sound from source is incredibly difficult - you just have to do everything well, ceiling , walls, caulking with fire caulk around windows on the inside, big gap windows that seal well (awning or casement about the only options  - fixed of course) floors, differential densities.

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## Moondog55

I honestly doubt that there would be much if any SPL difference between any of those fibre insulations despite the claims from the makers.
The only in wall acoustic insulation that I've found really effective for in-wall is Rockwool. We could only afford to do the bedroom in Rockwool but we notice the difference.
That said if a particular product is specified in the contract and a substitution was made without consultation and your approval I think that is a problem.
Have you done the insulation under floor yet? Are all joins and joints sealed with some sort of airtight flexible sealant, especially around the window frames?
If all of these things are not done noise will get in, it depends how much amelioration you are willing to pay for and if such steps are written into the contract and costed.
Ordinary double glazing is a compromise, we also need heavy drapes and curtains for the windows we have to equal the walls in SPL cut [ also in thermal efficiency] but the builder should have consulted you that is for sure but my gut feeling is that a compressed R4 batt will equal an acoustic batt. Part of the problem is that the walls in Australian houses are simply too thin to do much good, either acoustically or thermally, 120mm or 140mm is much better.
 What cladding are you using?
Is there battening and a gap between the house wrap and the cladding? If you have the money an effective solution is to add an extra layer there and something like Foilboard works very well

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## joynz

> I did a wall with green glue and16mm plasterboard and felt underwhelmed not noticing any significant difference. Admittedly all I could do was put my ear to the wall to discount the noise from other areas.

  If I had a major noise  issue at my place, I would be decoupling the wall by using resilient plasterboard mounts - especially with the plasterboard being stripped and replaced anyway. 
I’m assuming (hoping) that the OP got the advice of an acoustic engineer to advise on his/her traffic noise issue. 
I once helped someone install a very heavy vinyl product in their ceiling to to dampen traffic noise (they undertook several other measures too).

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## Basilratbrush

Yes, I know that’s what the specs are but when you compare side to side the 195 doesn’t actually look much wider than the 90mm
when I compress them and measure there’s literally no difference in thickness. I’m not sure how to upload a pic otherwise I would

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## phild01

> Yes, I know that’s what the specs are but when you compare side to side the 195 doesn’t actually look much wider than the 90mm
> when I compress them and measure there’s literally no difference in thickness. I’m not sure how to upload a pic otherwise I would

  I think something is wrong with what you are comparing, it should be very obvious with no doubt. Why are you compressing them for the comparison.

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## r3nov8or

Hey, Basilratbrush, when replying to someone, please click "Reply With Quote" so we know the context of your reply posts

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