Does anyone have experience with how much you gain by installing double layers of gypsum panels in the ceiling to dampen disturbing noise? We have our bedroom above one of the teenagers' rooms and it's incredibly noisy; the slightest sound can be heard up to us. Since we have slightly different evening routines, it's a bit stressful for sleep. The question is, do you gain anything from just gypsum, or should you also install a frame and perhaps add insulation boards between?
Hi! Gypsum is an excellent material, as many layers as possible, on soundproof studs (steel) screw on one side. Seal in the ceiling angle. Gyprock has a manual, but you must be at least an engineer to understand what it says.
I'm wondering the same thing! I've read a lot about a suspended ceiling with an air gap against the old ceiling, but we can't "afford" to reduce the ceiling height that much (100mm). Does it work with less, or is it not worth it then??
Thick gypsum works everywhere except on the ceiling is the impression I've gotten.
It probably depends on whether the disturbance is impact noise or airborne noise, like from conversation and stereo.Peter_K said:
In walls, it helps a lot to install double drywall, but then we're not dealing with impact noise...
I don't know how much double drywall helps against impact noise... But I believe the correct measure is to put some resilient material between two hard (possibly heavy) layers.
But read up on the drywall manufacturers' websites (norgips, gyproc, dangips, etc.) and the mineral wool manufacturers' websites (Paroc, isover, roxull, etc.).
I would have placed a layer of corrugated foam rubber inside the potential dropped ceiling (on the original ceiling, so to speak, directed downward). If one wants it quiet, a bitumen mat under this is extremely good.
What you're aiming for is partly to deflect sound waves and also to dampen those that "hit." This is how the "quiet rooms" that exist are constructed, with concrete walls.
What you're aiming for is partly to deflect sound waves and also to dampen those that "hit." This is how the "quiet rooms" that exist are constructed, with concrete walls.
There is plenty on the internet, search for some good keywords, e.g. impact sound *bjälklag
http://www.bygging.se/husbyggaren/artiklar/965789016.html
http://www.norgips.se/file?dnl=SE/projektering/4_1_takobjalklag_up0511_1997.pdf
http://www.makasi.se/Produktblad/Avjamning/Materialinformation/maxit Stepisol/Maxit_ljudgolv.pdf
But you might not have the opportunity to do anything on the topside ...
http://www.bygging.se/husbyggaren/artiklar/965789016.html
http://www.norgips.se/file?dnl=SE/projektering/4_1_takobjalklag_up0511_1997.pdf
http://www.makasi.se/Produktblad/Avjamning/Materialinformation/maxit Stepisol/Maxit_ljudgolv.pdf
But you might not have the opportunity to do anything on the topside ...
A plaster wall with 70 studs and single plasterboard has an R'w, i.e., a reduction in sound level weighted according to the A curve. The A curve is an adjustment based on how the ear perceives sound at different frequencies.
However, a single plaster wall reduces 30dB of sound between 50 and 3150 Hz. These are 7 octaves that are relevant for what the ear cares to listen to and what is relevant to measure since frequencies higher than 3150 Hz do not set a wall in motion as they are too short in wavelength.
A double wall, i.e., 2 layers of plasterboard per side, reduces 40 dB.
What is measured against is that if someone talks about 70 dB, the wall reduces 30 or 40 dB, i.e., on the other side, 40 or 30 dB "remain" to annoy.
A whisper is around 30 dB, normal speech at 40. Now that's not the whole truth, etc...
But with simple math, one can say that one layer of plaster reduces 5 dB extra. However, the distance between the plasterboards, i.e., the stud thickness, also governs. It determines the lowest frequency in the construction and all harmonic overtones, etc...
Then you can add some wool which dampens the construction by another 4-5 dB. Seal the plaster against floors, ceilings, and other places that break the plasterboard layer to minimize high frequencies.
Then it is that a heavy construction dampens lower frequencies; therefore, concrete/brick is exemplary in this purpose.
If we speak of airborne sound, impact sound should also be noted.
I could continue, but I'll stop here...
However, a single plaster wall reduces 30dB of sound between 50 and 3150 Hz. These are 7 octaves that are relevant for what the ear cares to listen to and what is relevant to measure since frequencies higher than 3150 Hz do not set a wall in motion as they are too short in wavelength.
A double wall, i.e., 2 layers of plasterboard per side, reduces 40 dB.
What is measured against is that if someone talks about 70 dB, the wall reduces 30 or 40 dB, i.e., on the other side, 40 or 30 dB "remain" to annoy.
A whisper is around 30 dB, normal speech at 40. Now that's not the whole truth, etc...
But with simple math, one can say that one layer of plaster reduces 5 dB extra. However, the distance between the plasterboards, i.e., the stud thickness, also governs. It determines the lowest frequency in the construction and all harmonic overtones, etc...
Then you can add some wool which dampens the construction by another 4-5 dB. Seal the plaster against floors, ceilings, and other places that break the plasterboard layer to minimize high frequencies.
Then it is that a heavy construction dampens lower frequencies; therefore, concrete/brick is exemplary in this purpose.
If we speak of airborne sound, impact sound should also be noted.
I could continue, but I'll stop here...
In some documents, I can read that impact sound is crucial for the soundproofing of intermediate floors. If this is true, it would be nice if you didn't stop at the wall issue, but continued with impact sound ... 
I agree with zankan, but I would fill the interlayer with stone wool and maybe even use two layers of drywall on the walls in the room below. If there is noise in that room, it travels through the walls up into the interlayer, so it might help to also use double drywall on them. Then the question is how much work you want to put into it.
Footstep noise is more challenging to resolve. But here, too, mass is key. Wood, in general, has very different mass depending on the type of wood, quality, etc. It doesn’t behave rationally (aside from being poor as sound insulation). However, in joists, it is a good material to build with, but worse at handling footstep noise. The dimension of the timber determines how well or poorly it performs. 20 cm of concrete does roughly the same as 1 meter of wood joist. Since footstep noise is a vibration in the structure that creates a wave on the underside of the floor, one should absorb the impact that creates the shock. Reduced span, proper timber dimension, cross bracing, etc., reduce footstep noise as well as increased mass in the joists.
A wall's sound insulation capability is measured by the reduction in sound the structure reduces. Footstep noise is measured by how much sound is created on the floor below, L’w, and this is also measured from 50-3150 Hz if I remember correctly. I recall it being 50dB in class A and 60 in Class C, where class A is particularly well sound-insulated.
To minimize footstep noise, it should be addressed at the source. It’s difficult to build away on the underside. The wave travels in the joist area and meets a wall, and some energy goes down into the wall. You can experiment with gypsum and insulation on the underside to "dampen" the sound.
A wall's sound insulation capability is measured by the reduction in sound the structure reduces. Footstep noise is measured by how much sound is created on the floor below, L’w, and this is also measured from 50-3150 Hz if I remember correctly. I recall it being 50dB in class A and 60 in Class C, where class A is particularly well sound-insulated.
To minimize footstep noise, it should be addressed at the source. It’s difficult to build away on the underside. The wave travels in the joist area and meets a wall, and some energy goes down into the wall. You can experiment with gypsum and insulation on the underside to "dampen" the sound.
That's roughly how I've come to understand it as well. Floating floors that rest on a slightly elastic layer, which dampens the impact wave's path downward through the flooring, is a pretty good solution, as far as I understand.zankan said:
But zankan probably knows this stuff 100 times better than I do.
Just to clarify since everyone is talking about footsteps and as far as I know he hasn't started walking on the ceiling yet it was actually noise from the floor below that's disturbing. Mostly talking, music, etc. I suspect that bass from stereo and clattering furniture, slamming doors, etc., are hard to get rid of as they propagate through the building's structure.
Doing something with the floor upstairs is not an option, but I'm possibly considering whether it's possible to unscrew all the floorboards and insulate the joists since it's so darn cold along the outer walls. This, of course, assumes that they haven't glued it in the groove.
it was actually noise from the floor below that's disturbing. Mostly talking, music, etc. I suspect that bass from stereo and clattering furniture, slamming doors, etc., are hard to get rid of as they propagate through the building's structure.Doing something with the floor upstairs is not an option, but I'm possibly considering whether it's possible to unscrew all the floorboards and insulate the joists since it's so darn cold along the outer walls. This, of course, assumes that they haven't glued it in the groove.
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Alright then.
Approximately 5 dB sound reduction per layer of plasterboard you attach!
But as mentioned, be mindful of sound sneaking past to the side. Seal all gaps in the wall-ceiling angle with latex caulk. Also consider what jerk suggested, double plasterboard on the walls in the children's room. But it depends a bit on how the ceiling/wall is constructed there. If there is unbroken ceiling material over the wall, it's not as critical, but if the wall is framed against the joists before the ceiling is installed, there is a high risk that sound spreads from there and up through the joists.
Insulation in the joists also helps as mentioned. Heavy insulation, like sawdust, dampens sound even better than mineral wool.
If you tear up to address both sound and floor coldness, you can check to ensure there's no leak to the outside world. Floor coldness often results from some air leakage or a thermal bridge at the floor's connection to the outer wall.
Approximately 5 dB sound reduction per layer of plasterboard you attach!
But as mentioned, be mindful of sound sneaking past to the side. Seal all gaps in the wall-ceiling angle with latex caulk. Also consider what jerk suggested, double plasterboard on the walls in the children's room. But it depends a bit on how the ceiling/wall is constructed there. If there is unbroken ceiling material over the wall, it's not as critical, but if the wall is framed against the joists before the ceiling is installed, there is a high risk that sound spreads from there and up through the joists.
Insulation in the joists also helps as mentioned. Heavy insulation, like sawdust, dampens sound even better than mineral wool.
If you tear up to address both sound and floor coldness, you can check to ensure there's no leak to the outside world. Floor coldness often results from some air leakage or a thermal bridge at the floor's connection to the outer wall.
Well, I suspect that the wind is blowing in at the eaves as it's drafty in the gaps between the floorboards in the built-in wardrobe. It's hard to know how everything is constructed since one wasn't there when it was built in 1965