Best model acoustic insulation for studs and joists?

[ashthekid]

What is the best brand/product for maximum acoustic performance for insulation between 2x4 400mm studs and joists?

I'm looking at all sorts and it's starting to get a bit confusing as so many difference varieties: slab, rolls, densities, rigid on one side, loft, cavity, etc.

I've seen on some threads that people say it doesn't really matter and you can stick loft insulation in-between the studs?

 

I'm thinking 100mm everywhere. just cram it in all over the place.

But some people have said you must have an air gap to improve performance.

 

Is Rockwool RWA45 any good? It's £30 per roll of 2.88sqm. It's 600mm wide though when really for ease and speed of installation I should be going for 400mm slabs shouldn't I?

 

There is another Rockwool one: Rockwool Sound Insulation Slab - 100 x 400mm x 1.2m

This is a different model but what is the difference?

Edited April 3, 2022 by ashthekid

[JohnMo]

We used Rockwool flexi, around 30mm thinner that the space we had to fill. So 100mm stud - 70mm, 140 stud - 100mm

 

You don't want it to touch either side of the plasterboard; as it will transfer more noise.

[Polish Builder]

If the product has higher density it means better acoustic / sound performance.

rolls will give you between 10-22kg/m3 density.

Insulation APR Rolls adapt to any slight imperfections in the substrate and knit together, eliminating any air gaps (thermal bridging).

The absence of air gaps is crucial to achieving a high level of performance in the relevant application.

Sound Insulation provides a high level of sound absorption, whilst also improving the thermal and fire performance of the floor, wall or partitions.

Acoustic Roll is particularly effective at preventing the hollow sound that can occur in partitions with unfilled cavities.

https://insulationgo.co.uk/100mm-ursa-terra-acoustic-insulation-roll-sound-insulation-apr-partition-walls-floors/ 

slabs from 45kg/m3 up to 100kg/m3 - designed for use in a variety of applications including internal partitions, timber and metal studs, and in between timber rafters and floor joists.

https://insulationgo.co.uk/75mm-rs45-knauf-rock-mineral-wool-building-slab-45kg-density-acoustic-insulation-multi-application/ 

https://www.insulationexpress.co.uk/rw5-acoustic-insulation-slab

https://www.insulationexpress.co.uk/blog/soundproofing-insulation.html

stone wool products work in two distinct ways to reduce noise, either by impeding the transmission of sound through an element of the structure or by absorption of sound at the surface.

[redtop]

We used r45 rockwool and just stuffed the frames with it. Works a treat at reducing sound transfer. I am sure there are better results, but this was quick easy and the end result is good enough for us.

[7dayworker]

On 04/04/2022 at 08:43, Polish Builder said:

If the product has higher density it means better acoustic / sound performance.

rolls will give you between 10-22kg/m3 density.

Insulation APR Rolls adapt to any slight imperfections in the substrate and knit together, eliminating any air gaps (thermal bridging).

The absence of air gaps is crucial to achieving a high level of performance in the relevant application.

Sound Insulation provides a high level of sound absorption, whilst also improving the thermal and fire performance of the floor, wall or partitions.

Acoustic Roll is particularly effective at preventing the hollow sound that can occur in partitions with unfilled cavities.

https://insulationgo.co.uk/100mm-ursa-terra-acoustic-insulation-roll-sound-insulation-apr-partition-walls-floors/ 

slabs from 45kg/m3 up to 100kg/m3 - designed for use in a variety of applications including internal partitions, timber and metal studs, and in between timber rafters and floor joists.

https://insulationgo.co.uk/75mm-rs45-knauf-rock-mineral-wool-building-slab-45kg-density-acoustic-insulation-multi-application/ 

https://www.insulationexpress.co.uk/rw5-acoustic-insulation-slab

https://www.insulationexpress.co.uk/blog/soundproofing-insulation.html

stone wool products work in two distinct ways to reduce noise, either by impeding the transmission of sound through an element of the structure or by absorption of sound at the surface.

Thanks . Those links are what I needed .great job 

[ashthekid]

I've purchased 50mm Rockwool Flexi Slab as there was a good deal on a pallet of it but i have since discovered it's only 33 kg/m3 which sounds crap in compariosn to anything else. This is intended to go inside the 100mm studwalls to allow for an air gap as well.

I'm considering getting the 100mm Flexi Slab for between the joists but after reading about how important the density is I'm considering RW5 or RW6 to really up the density to 100+ kg/m3. It seems RW6 is the best on the market with 140 kg/m3.

Will it really make a noticeable difference to the soundproofing?

[ADLIan]

Denser does not equal better - this is something pushed by Rockwool for many years.

 

The Approved Docs show a minimum density of 10 kg/m³ for mineral wool as an acoustic absorber in walls and floors. Someone posted a link on here some time ago to some very extensive research, I think done in Canada, that showed all mineral wool effectively does the same job and it is the use of denser plasterboard, double layer of plasterboard, acoustic studs, resilient bars etc that will improve the acoustic performance. Attached is an article from Knauf who make both glass wool and stone wool products.

 

Don't waste your money on ever denser Rockwool!

592690867_KnaufAcousticDensityArticle.pdf

[SimonD]

I posted these up a little while ago giving absorption coefficients for Rockwool and Knauf acoustic insulations:

 

https://forum.buildhub.org.uk/applications/core/interface/file/attachment.php?id=53703&key=6933e2a133c40aea7af458dc3a9054d0

 

https://forum.buildhub.org.uk/applications/core/interface/file/attachment.php?id=53702&key=0a4d463e77ddae0b111dc91878cb0bbe

 

As you'll see, 50mm isn't great, better to go for 75 or 100mm in your stud wall. Having a small airgap in there is a good idea. And also as per @ADLIan the insulation only plays part of the role, it's the whole buildup that makes it work.

[ADLIan]

Differences in the acoustic absorption make little or no difference to the overall acoustic performance as it is insignificant compared to the effect of the plasterboard, studs, quality of workmanship…….

 

The Canadian document I seem to remember listed 100’s of different combinations of insulation, timber/metal studs, plasterboard thickness, No of layers etc. The type and density of mineral wool made no difference; thicker wool giving a slightly better performance.

[ashthekid]

I've got plasterboard Knauf Soundshield Plus 12.mm going everywhere as standard which should hopefully help? I don't really have the space to do resilient bars. At a push I could perhaps double the plasterboard layer maybe if you think that will make a big difference. I have a little 15mm Soundshield Plus coming too.

 

And I could double up on the 50mm rockwool I already have to make it 100mm in the studs.

[redtop]

1 hour ago, ashthekid said:

I've got plasterboard Knauf Soundshield Plus 12.mm going everywhere as standard which should hopefully help? I don't really have the space to do resilient bars. At a push I could perhaps double the plasterboard layer maybe if you think that will make a big difference. I have a little 15mm Soundshield Plus coming too.

 

And I could double up on the 50mm rockwool I already have to make it 100mm in the studs.

I started with that and gave up as its soo bloody heavy for one person to lug around

[ashthekid]

Oh don't get me started on the weight of it!

It's crazy!

It better be worth the effort and expense.

[Conor]

We used isover 50mm acoustic rolls and they seem to be performing well. Little or no noise transmission between rooms (70mm metal studs, OSB and 12.5mm board)

Edited April 8, 2022 by Conor

[SimonD]

I've dug out the report @ADLIan refers to above. The link https://www.jhbrandt.net/wp-content/uploads/2014/11/ir761.pdf

 

I'll leave you to nerd out and make your own minds up about the various components as you may see it is not all entirely intuitive.

[Thorfun]

2 hours ago, SimonD said:

I've dug out the report @ADLIan refers to above. The link https://www.jhbrandt.net/wp-content/uploads/2014/11/ir761.pdf

 

I'll leave you to nerd out and make your own minds up about the various components as you may see it is not all entirely intuitive.

I didn't read the report in full but scanned the contents and I couldn't see anywhere about using 1 layer of OSB/ply and then one layer of plasterboard. I have a couple of builder friends who both board the walls with OSB or ply first before adding the layer of plasterboard on top. they say that this gives the wall a really solid feel.

 

how would that makeup compare to 2 sheets of plasterboard I wonder?

[ashthekid]

I'm definitely doubling up on plasterboard on the ceiling in a couple of the rooms to make doubly sure of no noise transfer.

I'm using Knauf Soundshield Plus everywhere in 12.5mm and 15mm in some rooms where it is dot and dabbed.

[SteamyTea]

Thinking off the top of my head, but isn't sound absorption more to do with scattering, interference and deflection?

So it becomes a combination of density, flexibility and shape.

 

 

I have often wondered if it is possible to make a relatively lightweight garden fence that deflects the outside noise back to the source, and even better if it could cause constructive interference.

Edited May 1, 2022 by SteamyTea

[SteamyTea]

Sculpted sound

 

23 March 2002

By Philip Ball

PUBLIC sculpture is all very impressive to look at, but what use is it? It just sits there providing a perch for pigeons and a backdrop for tourists’ photos. But a few years ago, Francisco Meseguer of the Institute of Materials Science in Madrid found an unexpected answer. He discovered that a minimalist sculpture on display in Madrid can block out sound. Erect such barriers throughout a noisy city or along the sides of a motorway and the tumultuous modern world might not only become a quieter place, but a more attractive one too.

The structure he stumbled across is called a sonic crystal because it scatters sound waves from a periodic array of “atoms”—anything from glass spheres to metal rods. Unlike conventional, solid sound barriers, sonic crystals are mostly empty space. And they’re a lot easier on the eye, too.

Now Meseguer and his colleagues have shown that these structures can do a lot more than simply block sound. Sonic crystals can shape and manipulate sound as if it were putty, reflecting, bending and filtering it in unexpected ways. They might even transform unpleasant environmental noise into something far more soothing.

And the Spanish team hopes to make similar structures for controlling other kinds of unwanted vibrations. In the grandest and, by their own admission, the craziest of such schemes, they think it might be possible to build gigantic sonic crystals that dampen seismic waves and protect buildings from earthquake damage.

 

Meseguer first stumbled across sonic crystals while he was working on tiny structures called photonic crystals. Developed in the 1980s, these can be used to manipulate light, and are now being turned into devices such as lenses and fibres for all kinds of optical communications technology (New Scientist, 12 June 1999, p 36).

One of the simplest forms of photonic crystal is simply a block of silica with a regular array of holes drilled in it. The difference in refractive index between the silica and the air in each hole means that light is scattered at the boundary where they meet. Make the distance between the holes about the same as the wavelength of light shining on it and the scattered photons interfere destructively. Simply put, the crystal blocks light in that range of wavelengths. It has a “photonic band gap”.

Nowadays, photonic crystals are often made by allowing microscopic glass beads to settle out of a suspension into organised lattices called colloidal crystals. Structures like these form in nature too. The iridescent appearance of opal, for instance, comes from the light-scattering properties of the tiny silica spheres that make up its lattice.

 

For photonic crystals with band gaps in the visible region of the spectrum, the holes or spheres must be a few hundred nanometres apart. But in 1995, while Meseguer was chatting with acoustics expert Jaime Llinares of the Polytechnic University of Valencia (UPV), they realised that if these structures were scaled up to centimetre dimensions—corresponding to the wavelength of sound—they might be able to create an acoustic analogue of a photonic crystal. Inside their imaginary sonic crystal, the scientists reasoned, sound waves should bounce off the “atoms” in such a way that the waves interfere destructively, cancelling out the oscillations in the air.

Llinares suspected that some form of sonic crystal might already exist. He remembered that on the UPV campus there was a sculpture by the Spanish minimalist artist Eusebio Sempere, made from an array of vertical metal bars of various lengths, of about the right thickness and spacing, like a set of surreal organ pipes. Could this block sounds?

To find out, they placed a loudspeaker on one side of the sculpture and a microphone on the other. The speaker broadcast white noise through the sculpture, but when they measured the intensity of the sound on the other side, there was no sign of a band gap.

The problem, they decided, was that the sculpture was made of hollow metal cylinders which resonated like organ pipes. Since some of the pipes were very short—about 10 centimetres, the same as the separation between pipes—they were resonating at frequencies inside the expected acoustic band gap, and this vibration masked the gap.

Fortunately, Sempere had constructed a similar, but larger bar sculpture, on display at the Juan March Foundation in Madrid. In this outdoor sculpture the pipes are up to three metres long. The two researchers set off with their loudspeaker and mic to try again. This time they found that the sculpture actually blocked out sound.

It wasn’t a perfect “crystal”, however, so the acoustic band gap was rather leaky. Worse still, the measurements were muddied by noise reflected from nearby buildings. To improve their data, the researchers decided to make their own minimalist sculptures by hanging cylinders of stainless steel or wood from a frame. This created a regular forest of bars that wouldn’t look out of place in any modern art gallery.

In 1998, instead of entering it for the Turner Prize, they mounted their crystal in an echo-free acoustic chamber and began experiments to measure how sound travelled through it. Their data revealed that the structure strongly suppressed sound waves in the audible range, at frequencies between 1400 and 1700 hertz. At last they had clear evidence of a sonic crystal.

Just months ago, the team also revealed how sonic crystals could be used not only to block sound but also to manipulate it (Physical Review Letters, vol 88, p 023902). At frequencies below the acoustic gap, sonic crystals are transparent to sound. But they don’t let sound waves pass unscathed. Just as light is bent by refraction when it passes from air into glass, so sound waves are bent when they pass into a sonic crystal.

The researchers realised that they could use this to create a lens that focuses sound. The lens they built is a convex array of cylinders (see Diagram). Put a sound source on one side and the lens focuses the sound waves on the far side. The focus is rather blurred, however, partly because the surface of the lens is quite rough—you can’t make a smoothly convex surface from a small number of cylinders, the structure is just too “grainy”. It’s like trying to make a lens from a handful of atoms.

 

 

They also built an acoustic analogue of another common optical device: a Fabry-Pérot interferometer. This is made from a stack of thin films that create interference patterns when light reflects off each layer. The acoustic version is simply a “slab” of sonic crystal, with rows of cylinders hanging parallel to the flat faces of the slab.

Fabry-Pérot devices are commonly used in microwave technology as filters. But Jose Sánchez-Dehesa, a physicist at the University of Madrid who worked on the project, admits that it is not yet obvious where the team’s sonic analogues of lenses and filters might be used, because they are so large.

The basic sonic crystal, however, which blocks sound waves within a tunable frequency band, might find all sorts of uses. Imagine a barrier made from crystals that are designed to have all the aesthetic qualities of a Sempere sculpture but which cuts out traffic noise on the far side.

“Sound-deadening barriers could be an interesting application of our findings,” says Sánchez-Dehesa. They would be more expensive than regular barriers, because they’re more elaborate, but he argues that in residential areas they would be a definite improvement on “ugly concrete panels”. His colleague Juan Vicente Sánchez-Pérez at UPV is now planning to patent a prototype sound barrier based on an array of cylinders.

Not everyone is convinced that sonic crystals offer any real advantages over conventional materials. Victor Krylov, an acoustics specialist at Loughborough University, believes that the sound barriers currently used along motorways and railways are at least as effective, and cheaper too.

Certainly, the need to space the cylinders at a distance of about one wavelength is a drawback, because it means that sound-proofing structures have to be big and thick. In 2000, however, Ping Sheng and his colleagues at Hong Kong University in Kowloon showed that there might be a way around this. They made sonic crystals from a cubic array of lead balls just one centimetre across, each ball coated with silicone rubber and glued into the array with epoxy resin. It was a kind of giant sonic opal. This structure displayed acoustic band gaps for sounds with wavelengths of around 1 metre and 25 centimetres—wavelengths that are hundreds of times as large as the spacing of the sound scatterers. They attributed this unexpected effect to the rubber-coated balls resonating at specific frequencies—they vibrate like heavy masses attached to springs.

Sheng’s colleague Che Ting Chan says the Hong Kong team are now making sonic crystals that absorb sound. They believe sonic crystals like these could be used to block sonar signals at sea, for instance. Make submarine hulls from this stuff and they would be invisible to sonar from ships or other subs.

Alternatively, say Peter Matic and Narendra Batra from the Naval Research Laboratory in Washington DC, the acoustic gap might be useful for filtering out particular frequencies generated by heavy machinery. They aim to design multifunctional materials which can be stiff and tough as well as providing acoustic shielding. Build them into a ship’s hull and you might be able to silence the sounds of the vessel’s engine, making it harder for submarines to detect.

Sánchez-Dehesa thinks it might even be possible to design barriers that change the quality of the sound as it passes through. Just as photonic crystals can filter the wavelength of light passing through, it might be possible to design a sonic crystal so that objectionable noise passing through it becomes more tolerable—even pleasant. “My goal is to look for a panel based on a sonic crystal that could transform bad sound on one side, like traffic noise, to good sound on the opposite side, like the sound of the trees or ocean waves.”

If that sounds daring, it is nothing compared to another idea they are toying with. Since these materials work for light and sound waves, it should be possible to build a structure that can block or transform other kinds of wave—including seismic waves in the ground. Just as you can make a slab of material impermeable to light by perforating it with a lattice of tiny holes, so you might make the Earth’s crust impenetrable for seismic waves by drilling an array of huge holes in it. Surround a city with such a lattice, and you could shield it from earthquakes. “If seismic shielding could achieve an attenuation of two points on the Richter scale [a hundredfold reduction in energy], it would be great,” Meseguer enthuses.

To test the feasibility of the idea, in 1999 Meseguer and his colleagues drilled two vertical lattices—one triangular and the other honeycomb-shaped—in a bed of marble in a local quarry. Each hole in these lattices was 6 centimetres across, 160 centimetres deep and separated from its neighbours by 14 centimetres. Then they created vibrations by dropping a steel ball bearing onto the quarry floor, and used sensors to measure how the vibrations passed through the lattices of holes. Both lattices significantly damped down the vibrations.

However, to protect against real seismic waves, the holes would have to be hundreds of metres across and at least a kilometre deep. “It is clear that such a proposal is not feasible yet,” confesses Sánchez-Dehesa. “But you can protect an isolated building.”

Used in this more modest way, underground “ring fences” of seismic crystals could make labs or buildings immune to vibrations such as those from passing trucks. This could be very useful, since some high-precision instruments—scanning probe microscopes for studying structure at the atomic scale, for example—are very sensitive to disturbance. Meseguer has already started looking at the practicalities of such a system. And who knows, one day these giant structures could become art in their own right.

 

A sacred bird’s voice seems to be trapped in the very stone of the Mayan Pyramid of Kukulkan at Chichén Itzá, surrounded by the jungles of the Yucatán Peninsula in Mexico. Stand at the foot of one of the stairways that climb the outer walls, clap your hands and a chirp rings back at you from the stone surface.

According to David Lubman, an acoustic consultant based in California, this is the sound of the quetzal bird, the spirit of the Maya incarnated in their plumed serpent god Quetzalcóatl. Lubman claims that it takes only a little imagination to hear in the curious echo from Kukulkan’s staircases the sound of the quetzal as it would have been heard by a Maya in the Peruvian cloud forest.

This, says Jose Sánchez-Dehesa, may be an example of Mayan acoustic engineering. Architects have designed buildings since ancient times to generate and exploit particular acoustic effects, such as the whispering gallery of St Paul’s Cathedral in London. But this is engineering of a particularly sophisticated kind: for the Kukulkan staircases, with their periodic array of scattering surfaces, have many of the characteristic features of a sonic crystal.

Could the Mayans really have known the secret of sonic crystals as long as 900 years ago? “I think the answer is yes,” says Francisco Meseguer. Sánchez-Dehesa agrees: “We can say that the Maya are the first people to harvest sound by making a sonic crystal.” And he hopes to prove it with a series of experiments at the pyramid. We may soon know whether the quetzal bird sings at Chichén Itzá by chance or design.

[ashthekid]

I ended up going for RW5 Rockwool slabs which has an amazingly high density to them for maximum sound absorbtion i'm told. Certainly much better than the RWA45 which is so popular because it's their most cost effective model.

[Nick Laslett]

Another link to the Canadian paper testing different wall build ups. 
 

[SteamyTea]

6 hours ago, Nick Laslett said:

Another link to the Canadian paper testing different wall build ups. 
 

Or not.

[markharro]

Ive had a read of this thread but still a bit confused. We have 90mm deep studs so the first question is what is the best thickness of wool to use - I assume 50 or 75mm but will one or other be better and sound blocking? The next issue is density...the roll products dont appear to list any density data so how the hell do you know what you are buying?! They seem a lot cheaper than the denser batt products but is it worth spending more on these - some of the comments on this thread suggest not? May use rolls for less critical areas and denser stuff for partitions that really do need to sound bloc?

Final question - where to get the best price - online or at local builder merchant?

 

thanks

[Gus Potter]

1 hour ago, markharro said:

Ive had a read of this thread but still a bit confused. We have 90mm deep studs so the first question is what is the best thickness of wool to use - I assume 50 or 75mm but will one or other be better and sound blocking? The next issue is density...the roll products dont appear to list any density data so how the hell do you know what you are buying?! They seem a lot cheaper than the denser batt products but is it worth spending more on these - some of the comments on this thread suggest not? May use rolls for less critical areas and denser stuff for partitions that really do need to sound bloc?

Final question - where to get the best price - online or at local builder merchant?

No wonder you are confused, I do this from time to time as the day job and suffer also. Bear with me..

 

The way I get my head round this is to think about how a speaker works.. an old one say one up from an Amstrad... take a step back and imagine yourself in flaired trousers.. listening to Santana you may not have been born then but.. there are pros and cons to that too.. the old days were not that great at times.. so be glad you missed it!

 

Anyway at the bottom you had the "woofer".. a big speaker that provided the base.. If you took the cover off you could see it moving... to be able to move it had to move lots of air but realtively slowly.

 

In the middle was a middle size speaker, you can't see this moving but it provided the middle frequencies. It moved less air back and forth but more quickly.

 

At the top was the tweater that was a small speaker. It delivered the high frequency so moved the air a little but quickly.

 

A light weight partition wall works in at least three basic ways. The big and low frequency air movement caused by the woofer, in the modern world equal to you having a low frequency " wind episode from your bottom" is resisted by the weight of the plaster board. The air gap takes out the high frequency and the glass wool the medium. All three layers act together to dampen their frequency response so it almost impossible to separate out each layers and tie that into the stiffness of the wal studs. As soon as you change the stud spacing (and length) any calculations need to be revised as the studs change the frequency response of everything that is attached to them..

 

As a starting point I would not look to save on the insulation thickness.. go for the 75mm as the labour cost to install is the same. Medium density wool will work fine at 75 mm. Go for at least a plaster board of 10kg/m^2.. but you'll find that standard 12.5mm plaster board just falls short, if in Scotland.  To get round this you can use Gyproc Wall TEN or often just skim coat the standard 12.5mm plasterboard.. gives you a much better job than Ames taping.

 

The critical thing is to stop flanking sound transmission. If you can pack the top and bottom of the wall so the sound does not get around it that will really deliver results.

 

Just remember that if you keep making the partition more heavy it may overstress the structure holding it up. If you spend time on the workmanship this will deliver the best result. Ideally this is something you want to do yourself (fitting the insulation) as you will take the time to do it right... few builders take the time to do this the right way.. unfortunately.

 

Lastly if you have wall sockets make sure they are not transmitting sound so insulate behind them. But before you adopt a solution just check with the spark that they are happy and don't have to uprate the cables..

 

Hope this helps.. keep your head up.

 

 

 

 

 

 

 

 

 

 

 

 

 

[SteamyTea]

6 hours ago, Gus Potter said:

in flaired trousers.. listening to Santana

Should use Black Magic Woman as the real test of the black arts.

 

 

 

And for the full spectrum, can't beat Woodstock in '69

 

 

Edited October 14, 2023 by SteamyTea

[Kelvin]

I was similarly confused. I looked at all the systems and decided that I couldn’t justify the expense so read that Canada report and did this:

 

1. sealed all joints and every gap. There are a lot of gaps and holes between rooms especially after first fixing paying particular attention to the wall to the edges. I treated it like airtightness 

 

2. fitted 75mm insulation in the walls and 100mm in the ceilings making sure there were air gaps as described above and that it went into all the edges

 

3. upped the plasterboard to 15mm and double boarded two of the rooms. 
 

4. plastered the walls 

 

Several of our rooms also have OSB on both sides of the wall. 
 

Hard to judge the performance as we are still building. Currently at the plastering stage. However, initial tests suggest it should perform pretty well. The bigger issue is likely to be the fact we are tiling the floor throughout so there will be gaps under the doors apart from one carpeted room. 

Edited October 14, 2023 by Kelvin