"Andy Hide" wrote in message
om...
My brother has just brought a c1920's terraced house. The houses along
the terrace are paired and it's the dividing wall between the paired
side that's causing the problem (i.e. front door next to front door).

From the non-paired side the noise is about what I would consider to
be "normal" i.e. muffled sounds. If someone was shouting you would
hear it but otherwise nothing more than thuds and maybe the faint
sound of voices if everything was quiet.

The paired side is another story. On this side you can hear
*everything* clearly. The wall appears to be double thickness house
brick. (not sure if there is a cavity or not).

On lifting a few of the floor boards it appears that the joists
supporting the floor are actually joined between the houses on the
problem side. There are 10mm gaps around the joists where they are
passed through the brickwork.

Does anyone have any ideas on how to reduce the level of noise ?

I had the following idea of:

1) Filling the gaps around the joists under the floor with expanding
foam.
2) Hardboarding over the floor to seal up any gaps between the boards
3) Gap filling under the skirting around the edges of the floor
4) Fitting a good quality carpet underlay
5) Fitting a good quality carpet.

Any ideas on whether this is likely to help the situation? I have read
other posts on this forum which talk about building a stud wall but am
not sure if this will help if the adjoined joists are the cause of the
problem.

Thanks,

Andy.

You seem to have the correct ( AFAIK ) ideas to start with. Noise leaks
disproportionately through small airgaps, so they are the first thing that
should be eliminated. Some other suggestions, not based on practical
experience I'm afraid: if you are able to get at the floor joists,
presumably this is from below? If so, you could stuff insulation between the
joists perhaps, as an alternative or in addition to hardboard. Maybe
Cellotex, which I believe is a foam sheet material, or rockwool, but the
rockwool would need to be held captive by something. Your suggestions all
seem sound, though I wonder if it would be better to stuff a stiff mix of
mortar around the joists where they enter the wall? Not sure, but mass is
good at reflecting sound, but foam doesn't have a lot of mass, maybe it's
better at absorbing sound. Finally, if you share floor joists with next
door, I wonder if they transmit sound along their length? Hard to tell, but
short of sawing them off at the wall and screwing them to a new wall batten
somehow, another idea would be to pour dry sand into the space between the
floorboards and the joists ( of course you would need some robust sheet
material screwed to the underside of the joists as well, to stop it falling
straight through ). The sand acts as additonal mass and, I believe, damping.
These are all finger-in-the-air suggestions, I can't argue with any of what
you are proposing, these are just ideas to try if you solutions don't work
as well as expected,

Andy.

My brother has just brought a c1920's terraced house. The houses along
the terrace are paired and it's the dividing wall between the paired
side that's causing the problem (i.e. front door next to front door).

From the non-paired side the noise is about what I would consider to
be "normal" i.e. muffled sounds. If someone was shouting you would
hear it but otherwise nothing more than thuds and maybe the faint
sound of voices if everything was quiet.

The paired side is another story. On this side you can hear
*everything* clearly. The wall appears to be double thickness house
brick. (not sure if there is a cavity or not).

On lifting a few of the floor boards it appears that the joists
supporting the floor are actually joined between the houses on the
problem side. There are 10mm gaps around the joists where they are
passed through the brickwork.

Does anyone have any ideas on how to reduce the level of noise ?

I had the following idea of:

1) Filling the gaps around the joists under the floor with expanding
foam.
2) Hardboarding over the floor to seal up any gaps between the boards
3) Gap filling under the skirting around the edges of the floor
4) Fitting a good quality carpet underlay
5) Fitting a good quality carpet.

Any ideas on whether this is likely to help the situation? I have read
other posts on this forum which talk about building a stud wall but am
not sure if this will help if the adjoined joists are the cause of the
problem.

Thanks,

Andy.

"Andy Hide" wrote in message
om...
My brother has just brought a c1920's terraced house. The houses along
the terrace are paired and it's the dividing wall between the paired
side that's causing the problem (i.e. front door next to front door).

From the non-paired side the noise is about what I would consider to
be "normal" i.e. muffled sounds. If someone was shouting you would
hear it but otherwise nothing more than thuds and maybe the faint
sound of voices if everything was quiet.

The paired side is another story. On this side you can hear
*everything* clearly. The wall appears to be double thickness house
brick. (not sure if there is a cavity or not).

On lifting a few of the floor boards it appears that the joists
supporting the floor are actually joined between the houses on the
problem side. There are 10mm gaps around the joists where they are
passed through the brickwork.

Does anyone have any ideas on how to reduce the level of noise ?

I had the following idea of:

1) Filling the gaps around the joists under the floor with expanding
foam.
2) Hardboarding over the floor to seal up any gaps between the boards
3) Gap filling under the skirting around the edges of the floor
4) Fitting a good quality carpet underlay
5) Fitting a good quality carpet.

Any ideas on whether this is likely to help the situation? I have read
other posts on this forum which talk about building a stud wall but am
not sure if this will help if the adjoined joists are the cause of the
problem.

Thanks,

Andy.


You could also shoot the neighbours. :-)

Not knowing exactly how these houses are constructed is a problem in giving good
advice on how to reduce the sounds percolating through. But the usual advice is
to fill all the air gaps between the two properties. Some of these terraced
builds have combined footings (foundations) and also shared loft spaces. This
can cause even the slightest sounds to travel through to next door by the
science of vibration along the shared timbers and the brickwork.

Placing cushion pads under any shared joists may also help to reduce the
vibrations travelling along them. The dividing wall could also be lined with
studio grade sound pads under a new plasterboard facing. Increasing the weight
on top of any shared structures will also help to reduce the vibrations along
them, but you then have to watch the bulk mass being carried on the original
build.

You could start by finding all the air gaps shared between the two houses and
filling them with an expanding foam. It's cheap enough to give a try and won't
hurt any.

"BigWallop" wrote
| Some of these terraced builds have combined footings (foundations)
| and also shared loft spaces.

Shared loft spaces can also be a major security risk, especially if any
other house in the terrace is unoccupied or squatted, and can become
attractive to vermin. On the upside they may provide an escape route from
fire, through the loft and across into neighbouring houses.

Owain

On 5 Jan 2005 10:26:23 -0800, (Andy Hide)
wrote:


In your case, sealing the joist holes with styrofoam sounds like a
good place to start. While you've got the carpets up you might want to
try is cover your floorboards with something airtight before
reinstalling the carpets. This would hopefully reduce the amout of
airborne sound coming up through the gaps bewteen the floorboards.

I have a similar problem, but I don;t know how much of the sound is
coming directly through the part wall. I am thinking of building a
double skin of 12mm plasterboard over the party wall, separated from
from it by a 3" gap, with rockwool in the gap. Comments appreciated.

J

"Jimmy" wrote in message
...
On 5 Jan 2005 10:26:23 -0800, (Andy Hide)
wrote:


In your case, sealing the joist holes with styrofoam sounds like a
good place to start. While you've got the carpets up you might want to
try is cover your floorboards with something airtight before
reinstalling the carpets. This would hopefully reduce the amout of
airborne sound coming up through the gaps bewteen the floorboards.

I have a similar problem, but I don;t know how much of the sound is
coming directly through the part wall. I am thinking of building a
double skin of 12mm plasterboard over the party wall, separated from
from it by a 3" gap, with rockwool in the gap. Comments appreciated.

J


Anything tightly packed into the gap is also going to transfer the sound
through, so don't put anything in between the new skin and the party wall. You
should also try to cushion the studwork away from the party to make sure it also
doesn't vibrate with the sounds acting on the party wall.

On Fri, 7 Jan 2005 17:03:15 -0000, "andrewpreece"
wrote:


Strictly speaking, whether packing the gap wth rockwool is good or bad
depends on whether more sound is transmitted by the rockwool, or whether
more is soaked up by it as the sound first goes through it the first time,
then reverberates in the gap between the party wall and the plasterboard.
There are two ways to kill sound, reflection and absorption and I daresay it
would be better to use both than just one or the other. I suspect that you
could hedge your bets somewhat by using rockwool but keeping it out of
contact with the plasterboard ( or party wall ). The whole subject of sound
reduction is a bit difficult, and the best you can do is adopt every
precaution.

The previous poster is right about the studwork needing to be decoupled from
the party wall, else it acts as a short circuit for sound to cross the
airgap. Quite how you go about that is another thing. I've heard talk of
resilient mounts or affixing the stud work to the floor and ceiling only, or
a combination of methods. Then there's the question of how you seal the
plasterboard to the ceiling/walls/floor around its perimeter: leave a gap
and you have a leakage path, fix the plasterboard solidly and you have a
sound 'short-circuit' of sorts! Good luck,

Andy.

Thanks to you and BigWallop for the comments,
Yes, I'm no expert on soundproofing, but I've notice when reading the
Building Regulations about methods of soundproofing ceilings, using a
second suspended ceiling attached at the walls but not touching the
existing ceiling, they rocommend using rockwool or similar in the
space between the old ceiling and the new one. They say it doesn't
matter if the rockwool is touching both surfaces, as long as it's not
packed tight - and that sounds about right to me.

Regarding doing a similar setup to sound-insulate a party wall, I am
thinking of using a timber frame (probably made of 2x2, fixed to the
floor, the ceiling and to the walls at each end of the room that are
90 degrees to the party wall. OK, there is bound to be a little bit of
soundwave transmission through the fixing points, but due to the
weight of the double skin of plasterboard, and the rockwool acting as
damping, I can't envisage much of that vibration acting on the double
layer of plasterboard, turning it into a giant soundboard. If the
resulting soundproofing is insufficient, another layer of plasterboard
can be added. In fact, come to think of it, it would make sense to
start off with a single skin of 12mm plasterboad and see if that's
suficient. If not, add another layer.

Going back to the question of whether or not to let the rockwool touch
both surfaces, I suspect it may be better to let it touch both
surfaces because it will then act as a vibration damper. I really
can't imagine that the rockwool itself will conduct sound waves into
the plasterboard unless it was packed very tightly indeed. As I said,
I'm not an expert. These are just my impressions based on real life
experience of how sound transmission behaves and from reading a few
things on the subject. Comments welcome.

J

"Jimmy" wrote in message
...
On Fri, 7 Jan 2005 17:03:15 -0000, "andrewpreece"
wrote:


Strictly speaking, whether packing the gap wth rockwool is good or bad
depends on whether more sound is transmitted by the rockwool, or whether
more is soaked up by it as the sound first goes through it the first
time,
then reverberates in the gap between the party wall and the
plasterboard.
There are two ways to kill sound, reflection and absorption and I
daresay it
would be better to use both than just one or the other. I suspect that
you
could hedge your bets somewhat by using rockwool but keeping it out of
contact with the plasterboard ( or party wall ). The whole subject of
sound
reduction is a bit difficult, and the best you can do is adopt every
precaution.

The previous poster is right about the studwork needing to be decoupled
from
the party wall, else it acts as a short circuit for sound to cross the
airgap. Quite how you go about that is another thing. I've heard talk of
resilient mounts or affixing the stud work to the floor and ceiling
only, or
a combination of methods. Then there's the question of how you seal the
plasterboard to the ceiling/walls/floor around its perimeter: leave a
gap
and you have a leakage path, fix the plasterboard solidly and you have a
sound 'short-circuit' of sorts! Good luck,

Andy.

Thanks to you and BigWallop for the comments,
Yes, I'm no expert on soundproofing, but I've notice when reading the
Building Regulations about methods of soundproofing ceilings, using a
second suspended ceiling attached at the walls but not touching the
existing ceiling, they rocommend using rockwool or similar in the
space between the old ceiling and the new one. They say it doesn't
matter if the rockwool is touching both surfaces, as long as it's not
packed tight - and that sounds about right to me.

Regarding doing a similar setup to sound-insulate a party wall, I am
thinking of using a timber frame (probably made of 2x2, fixed to the
floor, the ceiling and to the walls at each end of the room that are
90 degrees to the party wall. OK, there is bound to be a little bit of
soundwave transmission through the fixing points, but due to the
weight of the double skin of plasterboard, and the rockwool acting as
damping, I can't envisage much of that vibration acting on the double
layer of plasterboard, turning it into a giant soundboard. If the
resulting soundproofing is insufficient, another layer of plasterboard
can be added. In fact, come to think of it, it would make sense to
start off with a single skin of 12mm plasterboad and see if that's
suficient. If not, add another layer.

Going back to the question of whether or not to let the rockwool touch
both surfaces, I suspect it may be better to let it touch both
surfaces because it will then act as a vibration damper. I really
can't imagine that the rockwool itself will conduct sound waves into
the plasterboard unless it was packed very tightly indeed. As I said,
I'm not an expert. These are just my impressions based on real life
experience of how sound transmission behaves and from reading a few
things on the subject. Comments welcome.

J

I think you are right about the rockwool not transmitting too much sound if
it is loose: it has very little stiffness when loose, and its mass is very
little anyway so that sounds OK. You may also be right about it damping the
plasterboard a little, as the plasterboard will resonate slightly as the
sound strikes it. I have located an audio book, and there is a section in it
on sound reduction. The subject is complicated, with stiffness of walls
dominating at low frequency, then there's a resonant region, then there's
the mass-controlled region, then there's the coincincidence controlled
region, none of which is any use to you, but I will reproduce a littlte of
the more practical advice:-

"Cavity Walls: ...the springiness of the air between the cavities reacts
with the mass of the leaves to produce resonance. The resoant frequency
should be below 100 Hz which is achieved by a wide cavity ( 1m or more ) or
leaves of large mass, or boh.....these resonances can be reduced by
introducing an absorbent lining such as fibreglass into the cavity. It is
especially useful where practical considerations limit the thickness of the
wall thus raising the lower resonance above 100 Hz.
The sound reduction of a cavity wall is limited by the necessary edge,
tie and footing connections,as these form leakage paths to conduct sound
between the leaves. Any practical cnsideration which can miimise or even
eliminate these will greatly improve the sound reduction index"

"Flanking Walls: As these conduct sound into the receiving area, there is
lttle point in improving the insulation of the intervening wall beyond a
certan level unless the flanking walls can also be isolated structurally"

There is more info on damping, floating floors, ceilings, doors,
windows,airconditioning vents etc that I could provide on request,

cheers,

Andy.

On Sat, 8 Jan 2005 00:07:34 -0000, "andrewpreece"
wrote:


"Jimmy" wrote in message
...
On Fri, 7 Jan 2005 17:03:15 -0000, "andrewpreece"
wrote:


Strictly speaking, whether packing the gap wth rockwool is good or bad
depends on whether more sound is transmitted by the rockwool, or whether
more is soaked up by it as the sound first goes through it the first
time,
then reverberates in the gap between the party wall and the
plasterboard.
There are two ways to kill sound, reflection and absorption and I
daresay it
would be better to use both than just one or the other. I suspect that
you
could hedge your bets somewhat by using rockwool but keeping it out of
contact with the plasterboard ( or party wall ). The whole subject of
sound
reduction is a bit difficult, and the best you can do is adopt every
precaution.

The previous poster is right about the studwork needing to be decoupled
from
the party wall, else it acts as a short circuit for sound to cross the
airgap. Quite how you go about that is another thing. I've heard talk of
resilient mounts or affixing the stud work to the floor and ceiling
only, or
a combination of methods. Then there's the question of how you seal the
plasterboard to the ceiling/walls/floor around its perimeter: leave a
gap
and you have a leakage path, fix the plasterboard solidly and you have a
sound 'short-circuit' of sorts! Good luck,

Andy.

Thanks to you and BigWallop for the comments,
Yes, I'm no expert on soundproofing, but I've notice when reading the
Building Regulations about methods of soundproofing ceilings, using a
second suspended ceiling attached at the walls but not touching the
existing ceiling, they rocommend using rockwool or similar in the
space between the old ceiling and the new one. They say it doesn't
matter if the rockwool is touching both surfaces, as long as it's not
packed tight - and that sounds about right to me.

Regarding doing a similar setup to sound-insulate a party wall, I am
thinking of using a timber frame (probably made of 2x2, fixed to the
floor, the ceiling and to the walls at each end of the room that are
90 degrees to the party wall. OK, there is bound to be a little bit of
soundwave transmission through the fixing points, but due to the
weight of the double skin of plasterboard, and the rockwool acting as
damping, I can't envisage much of that vibration acting on the double
layer of plasterboard, turning it into a giant soundboard. If the
resulting soundproofing is insufficient, another layer of plasterboard
can be added. In fact, come to think of it, it would make sense to
start off with a single skin of 12mm plasterboad and see if that's
suficient. If not, add another layer.

Going back to the question of whether or not to let the rockwool touch
both surfaces, I suspect it may be better to let it touch both
surfaces because it will then act as a vibration damper. I really
can't imagine that the rockwool itself will conduct sound waves into
the plasterboard unless it was packed very tightly indeed. As I said,
I'm not an expert. These are just my impressions based on real life
experience of how sound transmission behaves and from reading a few
things on the subject. Comments welcome.

J

I think you are right about the rockwool not transmitting too much sound if
it is loose: it has very little stiffness when loose, and its mass is very
little anyway so that sounds OK. You may also be right about it damping the
plasterboard a little, as the plasterboard will resonate slightly as the
sound strikes it. I have located an audio book, and there is a section in it
on sound reduction. The subject is complicated, with stiffness of walls
dominating at low frequency, then there's a resonant region, then there's
the mass-controlled region, then there's the coincincidence controlled
region, none of which is any use to you, but I will reproduce a littlte of
the more practical advice:-

"Cavity Walls: ...the springiness of the air between the cavities reacts
with the mass of the leaves to produce resonance. The resoant frequency
should be below 100 Hz which is achieved by a wide cavity ( 1m or more ) or
leaves of large mass, or boh.....these resonances can be reduced by
introducing an absorbent lining such as fibreglass into the cavity. It is
especially useful where practical considerations limit the thickness of the
wall thus raising the lower resonance above 100 Hz.
The sound reduction of a cavity wall is limited by the necessary edge,
tie and footing connections,as these form leakage paths to conduct sound
between the leaves. Any practical cnsideration which can miimise or even
eliminate these will greatly improve the sound reduction index"

"Flanking Walls: As these conduct sound into the receiving area, there is
lttle point in improving the insulation of the intervening wall beyond a
certan level unless the flanking walls can also be isolated structurally"

There is more info on damping, floating floors, ceilings, doors,
windows,airconditioning vents etc that I could provide on request,

cheers,

Andy.

Thank you for posting that. Strangely enough, I learned a lot about
sound by studying loudspeaker eclosure design technique. Your passage
above touches on the subject of resonance. Where any two parallel
surfaces are involved (speaker cabinet or guitar soundbox or possibly
even a cavity wall) there will be a resonant frequency where a small
frequency range will be amplified. I'm not sure how relevent this is
to cavity walls. probably 'not very' if rockwool is loosely packed
into the cavity.

J

"Jimmy" wrote in message
...
On Sat, 8 Jan 2005 00:07:34 -0000, "andrewpreece"
wrote:


"Jimmy" wrote in message
...
On Fri, 7 Jan 2005 17:03:15 -0000, "andrewpreece"
wrote:


Strictly speaking, whether packing the gap wth rockwool is good or
bad
depends on whether more sound is transmitted by the rockwool, or
whether
more is soaked up by it as the sound first goes through it the first
time,
then reverberates in the gap between the party wall and the
plasterboard.
There are two ways to kill sound, reflection and absorption and I
daresay it
would be better to use both than just one or the other. I suspect
that
you
could hedge your bets somewhat by using rockwool but keeping it out
of
contact with the plasterboard ( or party wall ). The whole subject
of
sound
reduction is a bit difficult, and the best you can do is adopt every
precaution.

The previous poster is right about the studwork needing to be
decoupled
from
the party wall, else it acts as a short circuit for sound to cross
the
airgap. Quite how you go about that is another thing. I've heard
talk of
resilient mounts or affixing the stud work to the floor and ceiling
only, or
a combination of methods. Then there's the question of how you seal
the
plasterboard to the ceiling/walls/floor around its perimeter: leave
a
gap
and you have a leakage path, fix the plasterboard solidly and you
have a
sound 'short-circuit' of sorts! Good luck,

Andy.

Thanks to you and BigWallop for the comments,
Yes, I'm no expert on soundproofing, but I've notice when reading the
Building Regulations about methods of soundproofing ceilings, using a
second suspended ceiling attached at the walls but not touching the
existing ceiling, they rocommend using rockwool or similar in the
space between the old ceiling and the new one. They say it doesn't
matter if the rockwool is touching both surfaces, as long as it's not
packed tight - and that sounds about right to me.

Regarding doing a similar setup to sound-insulate a party wall, I am
thinking of using a timber frame (probably made of 2x2, fixed to the
floor, the ceiling and to the walls at each end of the room that are
90 degrees to the party wall. OK, there is bound to be a little bit of
soundwave transmission through the fixing points, but due to the
weight of the double skin of plasterboard, and the rockwool acting as
damping, I can't envisage much of that vibration acting on the double
layer of plasterboard, turning it into a giant soundboard. If the
resulting soundproofing is insufficient, another layer of plasterboard
can be added. In fact, come to think of it, it would make sense to
start off with a single skin of 12mm plasterboad and see if that's
suficient. If not, add another layer.

Going back to the question of whether or not to let the rockwool touch
both surfaces, I suspect it may be better to let it touch both
surfaces because it will then act as a vibration damper. I really
can't imagine that the rockwool itself will conduct sound waves into
the plasterboard unless it was packed very tightly indeed. As I said,
I'm not an expert. These are just my impressions based on real life
experience of how sound transmission behaves and from reading a few
things on the subject. Comments welcome.

J

I think you are right about the rockwool not transmitting too much sound
if
it is loose: it has very little stiffness when loose, and its mass is
very
little anyway so that sounds OK. You may also be right about it damping
the
plasterboard a little, as the plasterboard will resonate slightly as the
sound strikes it. I have located an audio book, and there is a section
in it
on sound reduction. The subject is complicated, with stiffness of walls
dominating at low frequency, then there's a resonant region, then
there's
the mass-controlled region, then there's the coincincidence controlled
region, none of which is any use to you, but I will reproduce a littlte
of
the more practical advice:-

"Cavity Walls: ...the springiness of the air between the cavities reacts
with the mass of the leaves to produce resonance. The resoant frequency
should be below 100 Hz which is achieved by a wide cavity ( 1m or more )
or
leaves of large mass, or boh.....these resonances can be reduced by
introducing an absorbent lining such as fibreglass into the cavity. It
is
especially useful where practical considerations limit the thickness of
the
wall thus raising the lower resonance above 100 Hz.
The sound reduction of a cavity wall is limited by the necessary
edge,
tie and footing connections,as these form leakage paths to conduct sound
between the leaves. Any practical cnsideration which can miimise or even
eliminate these will greatly improve the sound reduction index"

"Flanking Walls: As these conduct sound into the receiving area, there
is
lttle point in improving the insulation of the intervening wall beyond a
certan level unless the flanking walls can also be isolated
structurally"

There is more info on damping, floating floors, ceilings, doors,
windows,airconditioning vents etc that I could provide on request,

cheers,

Andy.

Thank you for posting that. Strangely enough, I learned a lot about
sound by studying loudspeaker eclosure design technique. Your passage
above touches on the subject of resonance. Where any two parallel
surfaces are involved (speaker cabinet or guitar soundbox or possibly
even a cavity wall) there will be a resonant frequency where a small
frequency range will be amplified. I'm not sure how relevent this is
to cavity walls. probably 'not very' if rockwool is loosely packed
into the cavity.

J

Yes, I missed one sentence out of the excerpt ..."In addition there is a
cavity resonance at about 250Hz which reduces sound insulation": this
followed the last sentence I reproduced in the 'cavity walls' paragraph.

I'm of an electronic background, and very similar effects occur with radio
signals, light or electrical waves going down cables. I would think that for
sound a resonance would occur where the gap between cavities is 1/2 a
wavelegth, as any sound wave of that frequency that reverberates back and
forth in a cavity will build up, rather than cancel out. Probably there will
be resonances at multiples of 1/2 wavelength as well, i.e. 1, 1.5, 2 etc. If
your cavity is 2inches and the speed of sound in air is 335m/s then I reckon
your lowest resonant frequency will be 3350 Hz! LOL, that doesn't tie in
with what the book says! Going with the stuff they talked about earlier viz
a 1m cavity and a resonance below 100Hz, I don't think they are talking
about standard size cavity walls, or 2" studwork.

None of which is very helpful, I suspect most of the noise you want to
eliminate will be below 1 or 2kHz anyway,

Andy.