Wiki: Stud wall noise reduction

[Tabby]

Feedback welcome...

NT

Stud wall noise reduction

There are many ways to reduce the noise transmission of plasterboard [[stud wall]]s. This article focuses on easily applied DIY solutions rather than recording studio practice.

The first rule of stud wall noise reduction is simple: don't build a [[stud wall]]. Concrete block walls can give better noise performance. However, often an existing stud wall isn't worth rebuilding.

Some of these methods are applied when building the wall, some are retrofitted to finished walls.

=3D=3DBasic principles=3D=3D Sound is movement or vibration, so all ways to block sound transmission reduce a wall's movement or vibration.

All the following contribute to reducing sound transmission:

*stiffness of frame *stiffness of plasterboard *mass *damping

The effects on fire resistance are considered too as the UK has 69,000 house fires a year and over 400 deaths a year in fires.

=3D=3DStandard methods=3D=3D =3D=3D=3DLarge framing=3D=3D=3D The beefier the timber frame, the stiffer it is and the less it bends when sound hits it.

=3D=3D=3DNoggings=3D=3D=3D Timber frames can be reinforced with noggings. One row helps, 2 rows help more. These stiffen the framework and also support the plasterboard more, reducing deflection & resonance, both of which pass sound.

_ _ | | | | | | | | | | | | | | | | | | | | | |____________| | | |____________| | | | | | | | | | | | | | | | | | |_| |_|

Horizontal nogging between 2 uprights

=3D=3D=3DThick plasterboard=3D=3D=3D

12mm plasterboard has more rigidity than 9mm, so less sound transmission.

1" of plasterboard is better again, ie 2 layers of 12mm. Staggering the joints in the 2 layers improves strength & resistance to cracking. [[Glue|Gluing]] the 2 layers to each other helps rigidity further.

Plywood is occasionally used in lieu of plasterboard. Its more abuse proof and supports fairly heavy loads. However its also flammable, and if used is best covered with a layer of plasterboard to give some fire resistance.

=3D=3D=3DHoles=3D=3D=3D Blocking all holes helps, even small holes can let a fair bit of sound through.

• Sound also transfers via the underfloor cavity, sometimes its worth lifting some floorboards and blocking this path

• Under door gaps can be blocked with brush strip or rubber strip

=3D=3D=3DWeights=3D=3D=3D Putting weights on noggings reduces frame movement in response to sound waves, reducing sound transmission. A row of concrete blocks can be used, or for less weight bricks or even hardcore.

=3D=3D=3DSound absorbent fill=3D=3D=3D Sound absorbent filling can reduce plasterboard resonance, reducing sound transmission. It also acts as a slight barrier to sound conduction through the cavity. To be effective the fill needs to be stiff, dense rockwool batts are ok, fibreglass roll loft [[insulation]] isn't.

Its best to avoid using scrap [[carpet]] as a fill. It has the necessary weight and some damping, but is flammable, and spills out in a fire, making things worse.

=3D=3D=3DStaggered frames=3D=3D=3D Constructing 2 separate frames within the one wall decouples the 2 sides of the wall from each other, reducing sound transmission. The 2 frames are staggered as shown to avoid the wall becoming twice as thick. However this does mean a lot more wood use, and the inability to fit noggings.

__ __ | | __ | | __ | | | | | | | | |__| | | |__| | | |__| |__|

Bird's eye view

=3D=3DLess popular methods=3D=3D =3D=3D=3DLead lining=3D=3D=3D Lead lining is seldom used. Its very effective but expensive. Lead sheet is fixed to the wall and overboarded. It provides mass and damping.

=3D=3D=3DScrap timber=3D=3D=3D Assorted timber offcuts can be fixed across plasterboard expanses to reduce plasterboard deflection & resonance. This differs from noggings in that

• the timber can be whatever size is to hand, typically much smaller than the frame

• connecting the timber to the wood frame is optional

• the timber doesn't add to frame rigidity

• several stiffening pieces are used per panel

• length isn't critical, pieces a bit too long are just placed on at an angle.

• The pieces can be fixed on with [[Adhesive|high grab glue]], or plastered & jammed into the frame.

This method is only doable when just one plasterboard skin is fitted. Its not a common approach, but its quick, easy & costs next to nothing, and reduces plasterboard deflection. Its useful when no more effective measures are to be taken.

=3D=3D=3DPlaster=3D=3D=3D When a wall has one skin of plasterboard applied, wet plaster is applied to the back of the PB to make it more rigid. No need for neatness or thoroughness makes it a fairly quick job. The extra plaster thickess improves rigidity, reducing plaster deflection & resonance.

The different resonant frequency of the 2 plasterboard sides means that at each resonant frequency, where sound transmission is a maximum for one side, its blocked by the other side.

=3D=3D=3DPanels=3D=3D=3D When a wall has one skin of plasterboard applied, panels of any sheet material to hand can be roughly cut & applied to the back of the PB to make it more rigid. Plasterboard offcuts are the obvious material, but other sheet material offcuts can also be used. This adds stiffness and weight, reducing deflection & resonance.

Plasterboard offcuts can be stuck with PVA, grab adhesive or plaster. Wood based sheet can also be screwed from the plaster side.

=3D=3D=3DJunk fill=3D=3D=3D Part filling a wall cavity with construction junk (eg plasterboard offcuts) can reduce plasterboard resonance to an extent. This is unlikely to make a dramatic difference, but is a free way to dispose of junk and get a little benefit.

Scrap plasterboard provides slight fire suppressance. Timber offcuts are better avoided as they're fuel.

=3D=3D=3DGravel fill=3D=3D=3D [image:Gravel filled wall 4682-2.jpg|right|185px]] [[image:Gravel funnel 4683-3.jpg|right|185px]]

Gravel filling [[stud wall]]s is not a recognised & recommended practice. It has been tried as an experiment by a uk.d-i-yer on a flimsy 1.5" timber frame wall with 2' stud spacing and 12mm plasterboard. Some panels were fully filled, and achieved excellant sound deadening, some panels were part filled, and were improved to a lesser extent.

The plasterboard didn't bend visibly. However this might not be ok with a beefier frame, the gravel weight with 2x4 studwork would be about triple.

The work cost about =A31 per 4' length of wall in materials for partial fill, and under a fiver per 4' for complete fill. The work involved was:

• cut a 2" hole in each panel

• shovel gravel in through a funnel (which was just the corner of a cardboard fruit & veg tray with a hole in it)

• Holes were made good with [[filler]]

In a fire, the gravel spills out and partially smothers the source of the flames.

Gravel fill can get excessively heavy, don't overdo it. Something lighter would be better for bigger frames.

Wet gravel shouldn't be poured onto electrical accessories.

=3D=3DSee Also=3D=3D

• [[Partition Wall]]

• [[Sheet Materials]]

• [[:Category:Noise|More noise reduction articles]]

• BBC, A guide to acoustic practice 1990]

• Camden walls & more complex multi-layer partition walls: Lightweight partitions having improved low frequency sound insulations. G.D. Plumb ]

• HVAC Acoustic Fundamentals]

• UFC 3-450-01 Noise and Vibration Control, US Army]

[[Category:Noise]]

[dom]

I think it needs to reference building regulations approved documents, Part E:

contains quite a few recommendations for stud walls, particularly where they form a building element that needs to meet a standard - adding such things as additional sealing to the edges of walls where they meet floors and ceilings.

Part B also needs a mention:

where stud walls form part of a compartment and must meet building regs for holding back fire.

[Terry Fields]

The table of the sound properties of various materials in this link suggests that fibreglass might have better perfomance than is suggested above:

site has a description of the basic science involved:

TF

[Tabby]

which is a different animal and ineffective

[dom]

Part E specifies mass >10Kg/m3, which I think does includes the denser mineral wool types.

[David Robinson]

You can fit noggins, but they have to be shallow, or the staggering needs to be the complete depth of the wood.

A standard non-staggered wall with larger timbers (e.g. with dimensions equivalent to the total of the comparable staggered wall) is easier and maybe just as good if not better (depending on the sound which is intended to be blocked). IMO!

Cheers, David.

[Tabby]

Thanks to everyone for the feedback so far. Revised version...

NT

Stud wall noise reduction

There are many ways to reduce the noise transmission of plasterboard [[stud wall]]s. Many of these methods also apply to plasterboard ceilings and timber floor structures, which are similarly constructed.

This article focuses on easily applied DIY solutions rather than recording studio practice.

The first rule of stud wall noise reduction is simple: don't build a [[stud wall]]. Concrete block walls give better noise performance. However, usually an existing stud wall isn't worth rebuilding.

Some of these methods are applied when building the wall, some are retrofitted to finished walls.

=3D=3DBasic principles=3D=3D Sound is movement or vibration, so all ways to block sound transmission reduce a wall's movement or vibration.

All the following contribute to reducing sound transmission:

*stiffness of frame *stiffness of plasterboard *mass *damping

The effects on fire resistance are considered too as the UK has 69,000 house fires a year and over 400 deaths a year in fires.

=3D=3DStandard methods=3D=3D =3D=3D=3DLarge framing=3D=3D=3D The beefier the timber frame, the stiffer it is and the less it bends when sound hits it.

=3D=3D=3DNoggings=3D=3D=3D Timber frames can be reinforced with noggings. One row helps, 2 rows help more. These stiffen the framework and also support the plasterboard more, reducing deflection & resonance, both of which pass sound.

_ _ | | | | | | | | | | | | | | | | | | | | | |____________| | | |____________| | | | | | | | | | | | | | | | | | |_| |_|

Horizontal nogging between 2 uprights

=3D=3D=3DThick plasterboard=3D=3D=3D

12mm plasterboard has more rigidity than 9mm, so less sound transmission.

1" of plasterboard is better again, ie 2 layers of 12mm. Staggering the joints in the 2 layers improves strength & resistance to cracking. [[Glue|Gluing]] the 2 layers to each other helps rigidity further.

Plywood is occasionally used in lieu of plasterboard. Its more abuse proof and supports fairly heavy loads. However its also flammable, and if used is best covered with a layer of plasterboard to give some fire resistance.

=3D=3D=3DHoles=3D=3D=3D Blocking all holes helps, even small holes can let a fair bit of sound through. Ensure all cracks & gaps are caulked.

• Sound also transfers via the underfloor cavity, sometimes its worth lifting some floorboards and blocking this path

• Under door gaps can be blocked with brush strip or rubber strip

• Downlighters can be plaster boxed

=3D=3D=3DWeights=3D=3D=3D Putting weights on noggings reduces frame movement in response to sound waves, reducing sound transmission. A row of concrete blocks can be used, or for less weight bricks or even hardcore.

=3D=3D=3DSound absorbent fill=3D=3D=3D Sound absorbent filling can reduce plasterboard resonance, reducing sound transmission. It also acts as a slight barrier to sound conduction through the cavity. To be effective the fill needs to be stiff, dense batts are ok, rolled loft [[insulation]] isn't. The denser the batts the better, acoustic grades are denser than thermal insulation and give more result at more cost. Greater density can be achieved with rockwool than glass fibre.

Fibreglass & mineral wool fill improve fire resistance. Scrap [[carpet]] isn't a good filling. It has weight and some damping, but is flammable, and spills out in a fire, making things worse.

=3D=3D=3DStaggered frames=3D=3D=3D

__ __ | | __ | | __ | | | | | | | | |__| | | |__| | | |__| |__|

Bird's eye view

Constructing 2 separate frames within the one wall decouples the 2 sides of the wall from each other, reducing sound transmission over much of the frequency spectrum. The 2 frames are staggered as shown to avoid the wall becoming twice as thick. However this does mean a lot more wood use, and only thin noggings can be used.

Sound transmission actually increases at the cavity's resonant frequency if the board is undamped, so batts or other damping are needed.

=3D=3D=3DMass loaded vinyl=3D=3D=3D Sand filled vinyl sheet was developed as a replacement for lead sheet for soundproofing. MLV is applied to the frame, [[tape]]d at the joins and boarded over. MLV provides mass & an extra barrier.

Roofing felt isn't a good substitute, its flammable & lighter.

=3D=3D=3DViscoelastic polymer=3D=3D=3D

2 layers of plasterboard are used per side with viscoelastic polymer gloop between them. The polymer gives damping, but its not one of the cheapest options.

=3D=3D=3DResilient bars=3D=3D=3D Thin steel bars stiffen the frame. Most useful on light frames.

=3D=3D=3DIsolation clips=3D=3D=3D These isolate the plasterboard from the framing.

=3D=3DLess popular methods=3D=3D =3D=3D=3DLead lining=3D=3D=3D Lead lining is the forerunner of mass loaded vinyl. Its very effective but not cheap. Lead sheet is fixed to the studs or the finished wall and overboarded. It provides mass and damping. Lead can be toxic to children so none may be left exposed, covered its safe though.

=3D=3D=3DSand=3D=3D=3D A thin layer of sand on ceilings provides mass and damping. Sand is very good at finding cracks & gaps and disappearing down them, care is needed in this respect. The sand is placed from above. Don't be tempted to use lots of sand, it only takes a little to provide damping, and excess weight can bring down a ceiling.

=3D=3D=3DPlaster=3D=3D=3D When a wall has one skin of plasterboard applied, wet plaster is applied to the back of the PB to make it more rigid. No need for neatness or thoroughness makes it a fairly quick job. The extra plaster thickess improves rigidity, reducing plaster deflection & resonance.

The different resonant frequency of the 2 plasterboard sides means that at each resonant frequency, where sound transmission is a maximum for one side, its blocked by the other side.

Other leftovers can also be used, such as lime plaster, tile adhesive & grout, artex, filler etc.

=3D=3D=3DPanels=3D=3D=3D When a wall has one skin of plasterboard applied, panels of any sheet material to hand can be applied to the back of the PB to make it more rigid. This adds stiffness and weight, reducing deflection & resonance.

Plasterboard & other sheet material offcuts can be used. Pieces don't need to be cut to match the shape of the PB, any odd bits all help add mass & stiffness, and it gets rid of the waste.

Plasterboard offcuts can be stuck with [[PVA]], high grab [[adhesive]] or plaster. Wood based sheets can also be [[screw]]ed from the plaster side.

Whole 4x8 sheets under the plasterboard are better and quicker, but not free.

=3D=3D=3DScrap timber=3D=3D=3D Assorted timber offcuts can be fixed across plasterboard expanses to reduce plasterboard deflection & resonance. This differs from noggings in that

• the timber can be whatever size is to hand, typically much smaller than the frame

• connecting the timber to the wood frame is optional

• the timber doesn't add to frame rigidity

• several stiffening pieces are used per panel

• length isn't critical, pieces a bit too long are just placed on at an angle.

• The pieces can be fixed on with [[Adhesive|high grab glue]], or plastered & jammed into the frame.

This method is only doable when just one plasterboard skin is fitted. Its not a common approach, but its quick, easy & costs next to nothing, and reduces plasterboard deflection. Its useful when no more effective measures are to be taken.

=3D=3D=3DJunk fill=3D=3D=3D Part filling a wall cavity with construction junk (eg plasterboard offcuts) can reduce plasterboard resonance to an extent. This is unlikely to make a dramatic difference, but is a free way to dispose of junk and get a little benefit.

Scrap plasterboard provides slight fire suppressance. Timber offcuts are fuel.

=3D=3DExperimental=3D=3D =3D=3D=3DGravel fill=3D=3D=3D [image:Gravel filled wall 4682-2.jpg|right|185px]] [[image:Gravel funnel 4683-3.jpg|right|185px]]

Gravel filling [[stud wall]]s is not a recognised & recommended practice. It has been tried as an experiment by a uk.d-i-yer on a flimsy 1.5" timber frame wall with 2' stud spacing and 12mm plasterboard. Some panels were fully filled, and achieved excellant sound deadening, some panels were part filled, and were improved to a lesser extent.

The work cost about =A31 per 4' length of wall in materials for partial fill, and under a fiver per 4' for complete fill. The work involved was:

• cut a 2" hole in each panel

• shovel gravel in through a funnel (which was just the corner of a cardboard fruit & veg tray with a hole in it)

• Holes were made good with [[filler]]

The plasterboard didn't bend visibly. However this might not be ok with a beefier frame, the gravel weight with 2x4 studwork would be about triple. Something lighter would be better for such frames.

In a fire, the gravel spills out and may partially smother the source of the flames.

Wet gravel shouldn't be poured onto electrical accessories in the wall.

=3D=3DBuilding Regs=3D=3D Newly built partition walls should meet build regs requirements

• Part E] Resistance to sound

• Part B] Fire performance requirements

=3D=3DSee Also=3D=3D

• [[Partition Wall]]

• [[Sheet Materials]]

• [[:Category:Noise|More noise reduction articles]]

• BBC, A guide to acoustic practice 1990]

• Camden walls & more complex multi-layer partition walls: Lightweight partitions having improved low frequency sound insulations. G.D. Plumb ]

• HVAC Acoustic Fundamentals]

• UFC 3-450-01 Noise and Vibration Control, US Army]

• soundproofing basics article]

[[Category:Noise]]

[Terry Fields]

I'm not nit-picking - for the sake of clarity and reinforcing the message it might be worth emphasising that the gravel chippings should be dry.

shovel *dry* gravel through....etc

All granular or powdery materials have a 'tap density', whereby when poured into a container and tapped, they can settle considerably - this is the 'contents may settle in transit' phenomenon of cornflakes, etc. 'Tapping' can easily add an extra 10 percent to the available volume when the filler is 'tapped'. To get the most performance out of the granular filling, working it in some way to get it to settle would be advisable: add a layer, settle it, add another layer, etc.

Perhaps a sentence like "working the gravel so that it packs down as it is added can increase the effective density of the fill and so increase performance" might make this clear.

HTH

TF

[Rob]

snip

Is permission or compliance needed to partition an existing room?

I'm pretty sure that doesn't constitute 'development' (planning) but it is 'an alteration project' - what I can't figure out is whether a simple partition affects 'ongoing compliance of the building'.

The room I have in mind is a second floor existing attic bedroom, and split in to two - basically because it's too difficult/expensive to heat the whole space.

Rob

[dom]

In my understanding, if the partition created a new "habitable room", then it should comply with building regs. So creating cupboards, wardrobes, larders, storage rooms etc would not. Creating 2 bedrooms out of 1, would.

[The Natural Philosopher]

Indeed.

I had considered it here, but it would not be possible legally: only one of the two windows is big enough to jump out of. ;-)

According to the regs, anyway. I climbed in and out of it well enough in the building process..

[Tabby]

Why do you say would the gravel need to be dry? I used wet with no problem.

Re packing, the voids aren't 100% full because its impractical to get it in higher than the bottom of the filling hole, plus the stone assumes a sloped pile type shape within the void. I didnt try packing the gravel down, as doing so would only increase lateral loading on the plasterboard, and the deadening effect of unpacked gravel is more than plenty. The ungravelled bit of PB at the top is far too small to do anything.

NT

[Terry Fields]

Just to reinforce your statement that "Wet gravel shouldn't be poured onto electrical accessories in the wall", recognising that while all walls need not necessarily hide electrical accessories, perhaps best practice would be to use dry gravel.

Fair enough.

TF

[Rob]

Ah, OK, thanks. I'll just check with the council as to whether either/both needed.

How is work like this enforced though, if the council isn't told?

In Sheffield (I'm sure it happens elsewhere) people seem to be be ever chopping up their living space into the most ludicrous 'rooms' - houses like mine (small-medium 3 bed terrace) is often seen as a 5 bed. I recently got PP for an extension and discussed the proliferation of uvpc windows with the planning officer (it's a conservation area) - he said they don't want to know unless they are told, and even then he wasn't sure they have enough staff to do anything about it.

Rob

[Hugo Nebula]

Provided it is not done as part of a change of use (i.e., house to flats, creating 'rooms for residential purposes' in a house in multiple occupation, etc.), then if the work (at any stage) adversely affects the structure or fire safety of the building, a Building Regulations application would be required.

If you were to partition a room into two separate rooms, for example, and you accessed the new room via a (fire)door through a non-loadbearing wall onto a landing, then you have not adversely affected the means of escape or the structure, so an application would not be required. If however, you created a room off an existing room, or put a doorway through a loadbearing wall (necessitating a lintel over), then this would be a material alteration requiring a Building Regulations application.

[Tabby]

Can we simply quote that in teh article?

NT

[Hugo Nebula]

Provided you clarify it: the above applies to England and Wales only; other parts of the UK have different regulations. You are also advised to check with Building Control at your local Council, as their interpretation of the Regulations may vary.

[Tabby]

cheers. done.

NT

[dom]

And both rooms met the requirements for total opening area of windows for ventilation (5% of floor space or use alternative fixed ventilation), and opening area of windows if means of escape is required (at least 450mm by 450mm and a minimum area of 0.3m2, no more than 1.2m above floor level - all IIRC).

So a thoroughly planned job requires a reading through of Part B fire protection, Part E sound, and Part F ventilation, to check for gotchas in relation to that particular design.

In practice, I'm sure few people pay much attention to the regs in small unsupervised projects not under building control. But I think we have a responsibility to draw attention to all the relevant regs, rather than someone comes a cropper when the BCO calls.