# Sound Proofing with Blown-In Insulation



## RMD (Feb 25, 2010)

I'm going to be getting foam injection insulation for my exterior walls to help with energy loss, and I was told I couldn't use this product in my ceilings.

I live in the bottom two floors of a 5 story browstone condo, and my upstairs neighbors are very loud. I don't think there is any insulation of any kind between their floors (hardwood, of course) and my ceiling drywall. I was hoping I could spray some foam in there to deaden the sound a bit.

The insulation installer recommended blown-in rockwool. He said it would require 2.5" holes to be cut at various places, but would not require the removal of the existing drywall.

Should I go with his recommendation? Any solution that requires the removal of the ceiling drywall will likely be a no-go because of the cost.


----------



## Wuzzat? (Feb 25, 2010)

You need to find out how the sound is being transmitted to your place.  
If your ceiling acts like a diaphragm then insulating it or stiffening it seems the way to go.
Soundproofing - Noise Reduction - Noise Abatement

Acoustiblok Inc., Soundproofing, Soundproofing Materials, Sound Deadening

There also may be zoning restrictions on how much noise they can legally make; your county would have to send someone out with a sound level meter.
Quiet Enjoyment

A 3 to 5 decibel noise reduction seems practical.
Sound Insulation


----------



## psych1 (Feb 25, 2010)

you may get some small benefit from filling the cavity with rockwool, but probably not a huge one.  The kind of sound you are getting floor to floor is different than what you get from outside.  Most of it is probably from direct impact on the floor above and so is transmitted by vibration of the buidling materials.  Insulating between the ceiling rafters blocks the sound transmitted through the air between the rafters, but not what is being transmitted through the rafters themselves and then through the drywall.  

Even in terms of insulating the air space, blown rockwool is not very dense and so not the most effective.  Foam would do better since it essentially glues everything together, effectively dampening vibration.  Maybe you can't do the injection type, but you could do the blown on type.  Even Rockwool batts (which are much denser than the blown in) would be better than blown in, but these solutions require removing the drywall.  

The best bet would probably be some combination of air space insulation and a second layer of drywall, preferably separated from the first by spacers.  Maybe a suspended ceiling would also help (although it might be ugly). 

Why is it so expensive to repalce drywall?  I would think that foam insulation would cost much more than drywalling - it would here.

You could also buy your upstairs neighbors carpet with a really thick underpad


----------



## RMD (Feb 25, 2010)

Thanks for the tips.

Sound is being transmitted multiple ways. Some sound is vibration transfer (footsteps, for instance), but I can also hear them talking. If they're playing music... forget it, no sleep for me.

I was given quotes in the $5000+ range for the removal of the existing ceiling drywall (< 200 sqft of ceiling) and replacing it with QuietRock. My ceiling is very "complex" (lots of cuts to be made).

Futhermore, not having the use of my bedroom even for a few days would be problematic given the size (small) of my condo.

Since I can get 75% off the cost of insullation installation, I thought it might be a cost effective way to at least partially fix the issue, plus the added thermal benefit. The idea of partially heating my jerk neighbor's apartment kills me.


----------



## inspectorD (Feb 25, 2010)

Try the rockwool, better than what you have, and you can always install another dampening system over the existing sheetrock if that does not help.

There are channels and insulation boards and standoffs for soundproofing..done in home theaters allll the time.

The insulation for the price..is the best way to go. 
I use Nu-Wool :: Premium Cellulose Insulation :: Home Page on most jobs.


----------



## psych1 (Feb 25, 2010)

RMD said:


> Thanks for the tips.
> 
> I was given quotes in the $5000+ range for the removal of the existing ceiling drywall (< 200 sqft of ceiling) and replacing it with QuietRock.




wow that must be a complex job.  I would have guessed you could do it in oak for that 

I agree that it would be worth doing the rockwool as an initial step.  Wuzzat, are you reccomending cellulose?  I hadn't thought of that, but it is pretty dense and soundproof as well.


----------



## Nestor_Kelebay (Feb 25, 2010)

> If they're playing music... forget it, no sleep for me.



This is almost certainly the one thing that you can do A LOT about at very little cost.

RMD:

     To be honest with you, I wish you would read the paper by Mr. Quirt of the Canadian National Research Council on reducing noise transmission through building components like walls, floors, ceilings, windows and doors.

Sound Transmission Through Building Components - NRC-CNRC

That will convince you that the noise reduction you're likely to get by blowing cellulose insulation into your ceiling joist space is gonna be a disappointing waste of money.  There are two reasons for this:

1. The first one is that adding sound absorbing materials like insulation to a wall, floor or ceiling is pretty well a waste of time and money if there are studs or floor joists that connect the two sides of the wall, floor or ceiling.  That's cuz any movement of one side of the wall or floor is going to result in the simultaneous and equal amount of movement on the other side of the wall or ceiling, so any sound wave hitting the wall or floor is going to be accurately reproduced by the other side of that wall or ceiling.  Sound absorbing materials are only helpful when you don't have any mechanical linkage between your wall and your neighbors, or your ceiling and your neighbor's floor.  You can do that by building two walls, or using a 2X6 as the bottom and top plates, and staggering the 2X4 studs so that half of them support the drywall on one side and the other half support the drywall on the other.

2. And the second reason why is that sound is a pressure wave in the air and behaves all the laws of physics just like any other wave does.  It's the fact that sound is a wave that allows me to explain in simple terms why the cellulose insulation in the ceiling won't do very much good.

When a sound wave hits a wall, floor or ceiling what happens is that the wall, floor or ceiling moves in response to the changing pressure on one side of it.  It is that movement of the wall, floor or ceiling that reproduces another sound wave on the other side of the wall, floor or ceiling.  It is this second "reproduced" sound wave that that we hear, NOT the original.

And, I can prove that by showing how the Mass Law results in our hearing only a "BOOM-BOOM-BOOM" and not all of the music when someone is having a party late at night in the same building we're living in.

The "Mass Law" is one of the basic principles of accoustics.  The Mass Law says that for every:

a) doubling of the mass per given area of the wall, floor or ceiling, or

b) doubling of the frequency of the sound waves hitting the wall, floor or ceiling, then

the sound pressure level of the "reproduced" sound wave on the other side of the wall, floor or ceiling will be reduced to 1/4 of it's initial value, or by 6 decibels.

And the reason why is that by doubling the mass of the wall, you also double it's inertia.  When you do that, the wall simply doesn't move as fast or as far under the same applied force.  The smaller and slower movement of the wall means that the reproduced sound wave is lower in amplitude, which our ears recognize as being "quieter".

Similarily, if you double the frequency of the sound waves hitting the wall, then the inertia of your existing wall makes it progressively harder and harder for your wall to change it's direction of movement fast enough to respond to the sound waves hitting it.  Once the frequency is high enough that the inertia of the wall prevents it from moving in response to those sound waves, the wall simply stops moving in response to those sound waves, and that means the wall stops moving.  Unless something else is making noise on the other side of the wall, it's quiet on the other side of the wall.

It is these simple principles of physics that explain why you hear BOOM-BOOM-BOOM when there's a party going on in your building late at night.  What's happening is the midrange and treble frequencies are too high for the walls and ceilings to respond to, so you don't hear them.  The only frequencies that are low enough for the walls and ceilings to respond to are the deep bass frequencies.  Consequently, your walls and ceilings only move in respond to those low frequencies, and that's the only sound that is reproduced by the walls, floors and ceilings.  This is why you only hear BOOM-BOOM-BOOM when they're playing a song you know well.  You have to get close enough to the source of the sound so that there are no walls, floors or ceilings between you before you will hear the midrange and trebel and recognize the music being played.

OK, so if you blow this cellulose insulation into the space between the ceiling joists, the amount it's going to help is going to be directly proportional to the amount it increases the mass per square foot of what's there now.  It's only going to help significantly if your neighbor's wall wasn't mechanically connected to your ceiling by the joists.  That's because the joists connect both sides of the floor structure, and so movement of the neighbor's floor is going to result in exactly the same movement of your ceiling.  So, you can consider the entire floor/joist/ceiling a single "wall" of uniform composition and density and apply the Mass Law.  You can do a rough calculation on your own.  You know wood floats, so it's density has to be less than that of water.  0.8 say.  It shouldn't be hard to find out how much a 1/2 inch by 32 square foot sheet of drywall weights and you know the area of your ceiling (roughly).  And, you can probably assume 2X12 fir joists on 16 inch centers.  Now add to that 12 inches (say) of cellulose insulation at, what, 3 or 4 pounds per cubic foot say (?) to see how much of a percent difference you're gonna make in the mass of that "wall" over your head.

Here's my best advice:

1. Deal with the stereo first:  Explain what I've explained to you to your neighbor, and make him an offer:  You'll buy him a set of good quality ear phones (which he will return when either of you move) if he will agree to turn the bass control on his stereo (or music source) all the way down when he's not using the ear phones.  Since the source of the low frequency sound is the movement of the walls and floors in response to the low frequeincy sound created by the woofers, by stopping the movement of the woofers, we eliminate the bass frequencies which cause the "BOOM-BOOM-BOOM" you hear in your condo.

2. Deal with the foot steps next:  Make your upstairs neighbor another offer:  If he installs carpet in his apartment, you'll go halfers on a thicker and better quality underpad to go under it.  (I know this is killing you.)  The reason why the footsteps are loud is because the whole floor/joist/ceiling structure moves in response to 175 pounds suddenly coming down on it in one spot and causing it to vibrate.  That's called "impact loading".  By having a thick underpad under the carpet, you slow the rate at which that load is applied to the floor, (cuz underpad foam rubber is a lot softer than shoe heel rubber so it compresses more over a longer period of time) and that slows the movement of the floor/joist/ceiling in response to footsteps.  If the movement of your ceiling is slower, then the sound pressure wave created when it moves is weaker (which means that the air pressure doesn't change as much as fast), and that translates into "quieter" noise.

The problem, of course, is that he might not want to give up his hardwood floor.

I'd look up "Engineers, Accoustical" in your yellow pages and phone one of them up.  Explain what you've learned from posting online and reading various papers and see if he agrees that the earphones/underpad will be both more effective and considerably less expensive than the insulating idea.

There are noise and vibration isolation devices but to retrofit a building with these, even around one condo is likely going to be cost prohibitive.

Also, you already know that increasing the MASS of your floor/joist/ceiling structure is the single biggest factor in determining how much noise comes through.  So, spending $5000 to REPLACE the drywall on the ceiling with Quietrock (whatever that is) is likely to be less effective than spending $3000 to ADD a second layer of ordinary drywall to your existing ceiling.  Obviously, your drywall contractor doesn't know much about accoustics.

Click on the link above and read through it before making any decisions.

(Aside:  Also remember that our hearing isn't linear.  We hear quiet sounds much better than louder ones.  So, a 25% (or 6 dB) reduction in the sound pressure level won't seem to be only one quarter as loud as it was before.  You'd probably perceive a 6 dB drop in the noise level to be "half as loud" as before (at best).)

PS:  The Canadian National Research Council is a government funded research group that does research into problems pertinant to Canadians and the Canadian climate.  They do a lot of research on insulation and energy savings.  You can access all of the information available from the Canadian National Research Council on their web site at:
http://www.nrc-cnrc.gc.ca/eng/index.html
Then left click on Library and Publications
Then left click on NRC Publications
Then click on Browse by Subject
You should be able to find the paper by J. A. Quirt under the heading "Construction", but it may take a while since the NRC has issued 16,488  publications under that general heading.  (Best to use the "Advanced Search" feature and type in part of the title.)
In case you hadn't thought of it, the NRC web site is an excellent tool to research just about any subject; as is Google itself.


----------



## Wuzzat? (Feb 26, 2010)

psych1 said:


> Wuzzat, are you reccomending cellulose?  I hadn't thought of that, but it is pretty dense and soundproof as well.


Whatever gives you the most decibel reduction per installed dollar.


----------



## RMD (Feb 26, 2010)

Again, good tips from everybody.

Quiet rock is 5/8 drywall that has the same sound dampening as 8 sheets of normal drywall. That's why its so expensive.

In terms of the insulation not helping the sound very much, its gotta be better than what I have now, and will at least help my heating bill.


----------



## Nestor_Kelebay (Feb 26, 2010)

RMD said:


> Quiet rock is 5/8 drywall that has the same sound dampening as 8 sheets of normal drywall.



Is that what people that have had it installed say, or is that what the company that makes it says in their advertising?  I expect that if you ask to talk to some "satisfied customers" you might hear sumthin diffrnt.



> In terms of the insulation not helping the sound very much, its gotta be better than what I have now, and will at least help my heating bill.



I realize I'm telling you something you don't want to hear.  The biggest step forward you can make would be to get on speaking terms with your upstairs neighbor so that he'd be open to co-operating with your efforts.


----------



## RMD (Feb 26, 2010)

I've heard QuietRock in action, and it's pretty impressive. The company publishes STC ratings which back up their claims.

See: QuietRock Soundproof Drywall

The big downside is that it's really, really expensive.

Also, as far as getting on "speaking terms" with my upstairs neighbors, it's pointless. For one thing, I can easily hear even "normal" levels of conversation. So even if they decided to not be jerks, I would still hear everything.

These people have a party until 4am nearly every weekend. When I call to complain at 4am, they act surprised. Every. Single. Time. They do it to spite me now.

My only other option is to have them evicted. I own 38% of the building, so just need one other unit owner to agree, and their lease can't be renewed. If I can't come up with another solution, that's what will have to happen.

But, as I said, even if that happens, if somebody new moves in, it will still be loud.


----------



## Wuzzat? (Feb 26, 2010)

RMD said:


> I've heard QuietRock in action, and it's pretty impressive. The company publishes STC ratings which back up their claims.
> 
> See: QuietRock Soundproof Drywall
> 
> The big downside is that it's really, really expensive.



That's a good link; you're buying decibels of attenuation and with this link you can see how much difference each product makes.
QuietRock - Wikipedia, the free encyclopedia

But I'd feel better if I could see the STC 80 test spec's.  I'd think it should be traceable to NIST.
http://www.greengluecompany.com/understandingSTC.php
http://www.patentstorm.us/patents/7181891/fulltext.html

If you can get the dbs of attenuation, plot them vs price and see if there is a breakpoint or knee in the curve where you get especially good attenuation per dollar spent.


----------



## Nestor_Kelebay (Feb 26, 2010)

RMD:

I'd go to the places that sell and/or install the stuff and tell them you're thinking of buying it, but you'd like to talk to some "satisfied customers" first.

The bottom line here is that people who've had it installed in their own house are going to be more honest with you than anyone trying to sell it to you or install it for you.  The former don't have a vested interest in influencing your purchase decision.


----------



## Ted White (Mar 8, 2010)

You can easily replace pre-damped drywall by field-installing damping material instead. The results are much higher and much cheaper. Less waste.

One Sheet = 8 is a marketing talking point only. Never demonstrated in the real world.

Foam is the worst material you could deploy, as it will likely couple the two surfaces and conduct vibration.


----------



## RMD (Mar 8, 2010)

Ted White said:


> You can easily replace pre-damped drywall by field-installing damping material instead. The results are much higher and much cheaper. Less waste.
> 
> One Sheet = 8 is a marketing talking point only. Never demonstrated in the real world.
> 
> Foam is the worst material you could deploy, as it will likely couple the two surfaces and conduct vibration.



What do you recommend for damping material, and if you had to guess, what would you estimate a 180 sqft ceiling (with 2 pot lights, a ceiling fan, and a smoke detector) would cost to redo?

The quotes we've received seem totally astronomical.


----------



## Ted White (Mar 8, 2010)

When I hear about such high quotes, it's often from a contractor that just isn't sure what to do, so they quote high to cover themselves.

Ballpark:

Labor to remove drywall existing: $100
Fiberglass Insulation: $100
Resilient clips and Channel: $125
Damping material like Green Glue: $150
Double drywall, including waste: $100

Labor for above: $500. So a total of $1200 to $1500 I'd say.

The trick is to have the contractor completely understand the scope of work and have him understand that you understand the scope of work as well.


----------



## Nestor_Kelebay (Mar 8, 2010)

Apparantly, this Quietrock costs $120 US per sheet.  It consists of a sheet of lead sandwiched between two layers of drywall.  Maybe the high cost estimates are because you can't cut this stuff like ordinary drywall; you have to cut it with a saw of some sort that will cut through lead (like a jig saw with a metal cutting blade).  Also with a sheet of lead inside it, then the stuff is going to be a lot heavier than ordinary drywall, and that would add to the cost of installation as well.


----------



## Ted White (Mar 9, 2010)

There is no lead in quiet rock. Standard drywall or cement board is used, same as you can buy.

QR530 uses a sheet of thin steel to allow for a second damping layer. This was abandoned when they started to make the QR525

The steel requires a circular saw to cut without delaminating.


----------



## DavidLuke (Apr 13, 2010)

QuietRock costs $40 for the 510 model. Lowe's sells quietrock for $43. It's mentioned in the site aswell. If you are doing it yourself a layer of drywall, and then a layer of quietrock and some glue should not cost much for an entire room. The other models have sheet metal in it but that will be hard to cut.


----------



## Ted White (Apr 13, 2010)

Hi David,

If anyone is contemplating pre-damped drywall, consider:

Any pre-damped drywall is simply layers of standard boards and damping compound. There is simply no mystery to the materials. So the decision to use these pre-damped boards comes down to:

Price  (less is better)
Mass (more is better)
Damping (more is better)

Generally you will always be able to field assemble a more massive, more damped and less expensive panel. An additional plus is that field assembly will allow you to overlap seams between the drywall layers.

As a side note, while I respect QUiet SOlutions for providing test data on their high performance panels, I wonder why the same acoustic test data is missing for the lower cost panels. If you tout something as acoustically beneficial, you need to provide the lab data (it exists).


----------



## DavidLuke (Apr 21, 2010)

Hi ted,

Agree with your statement Any pre-damped drywall is simply layers of standard boards and damping compound.
But this process of making them is time consuming. Quiet Solutions has full TL data by frequency available for their expensive drywall and not for the inexpensive panels. And I do not know why.


----------



## Ted White (Apr 21, 2010)

David,

Without boring the larger audience with excessive details, let me say that I am familiar with the manufacturing of damping compounds at the molecular level, as well and the factory assembly of these pre-damped panels. I have been involved with the R&D of constrained layer damping materials and systems since 2003. I have consulted with 3 of the 4 manufacturers who make these pre-damped panels.

There is no time consuming aspect of this in any form. It's very fast. To add mystique to the process is simply misleading.

Due to expenses like freight costs, factory damped panels are naturally and understandibly more expensive, but also have more expensive waste, and have generally lower performance than a field assembled panel (due to either lack of mass, lack of damping or some combination thereof). 

They are all fine products, however.


----------



## beads4breakfast (Sep 26, 2010)

Hi, I have the same problem with airborne noise coming from an upstairs apartment occupying the third floor of my home.  My bf and I are looking for an easy solution to reduce this noise with minimal cost and damage to the exisiting ceiling.  We just put the ceiling up and really don't want to take it down and start over.  We hear everything, every creak, the ice machine, the phone ring, talking...everything, and the tenant says the same for us.

  We have the soundproofing, thicker sheet rock that you guys discussed in previous threads throughout the house on all the walls and the ceilings.  It acts as a great barrier for the walls but does absolutely nothing for the ceiling.  There is no insulation in the ceilings, or soundproofing on the flooring in the apartment, just plywood flooring with click flooring on top, and the thicker sheet rock on the ceiling.  

I'm curious to know what you did as a solution to your airborne noise problem, and how it's working for you.

Thanks


----------



## Ted White (Sep 26, 2010)

How to Soundproof a Ceiling | Soundproofing Ceilings Solutions | Soundproofing Company

This article gives you several options and an understanding of what you're up against.


----------



## beads4breakfast (Sep 27, 2010)

Yes Ted,
It certainly did give me lots of food for thought. This whole site should provide a wealth of information while we renovate is old house of ours.  It was built in 1904.
 What I was asking was how RMD handled his problem with the noise and was it effective. in elininating or minimizing the problem.

Thanks,
Kim


----------



## handyguys (Sep 27, 2010)

Ted knows his stuff, his advice is sound. We talked about some of this in a podcast here Episode #54  Keeping the noise out


----------



## Ted White (Sep 27, 2010)

Thanks. I would not suggest the concept of a suspended ceiling for sound isolation.


----------



## handyguys (Sep 27, 2010)

Ted White said:


> I would not suggest the concept of a suspended ceiling for sound isolation.


 I don't like them either.

As has been said, just another drywall layer will do more than blown in insulation. Decoupled drywall would be even better.


----------



## PatHIverson (Sep 28, 2010)

Nestor_Kelebay said:


> This is almost certainly the one thing that you can do A LOT about at very little cost.
> 
> RMD:
> 
> ...



This is extremely helpful... Great resources....Thanks again for the share.

Cheers.


----------



## PatHIverson (Sep 28, 2010)

handyguys said:


> Ted knows his stuff, his advice is sound. We talked about some of this in a podcast here Episode #54  Keeping the noise out



I like the diagrams. Thanks for the troubles.. Cheers


----------



## Ted White (Sep 29, 2010)

Just to refine a point or two. We have the following elements to help us isolate sound:

*Decoupling*- Staggered studs, double studs, resilient clips&channel, and resilient channel are all common methods to decouple walls and ceilings.

*Absorption*- Some material in a sealed air cavity (in our case) that increases the resistance to sound wave movement, thereby robbing the waves of energy. A very large volume of air can accomplish this, but our walls are limited in depth. We add a low-medium density insulation to increase the resistance without introducing conduction. This is a thermodynamic process, whereby the introduction of open-fiber insulation essentially mimics a system with a much bigger air cavity.

*Mass*- This is primarily the job of materials like drywall and plywood. Could be masonry if wer're looking at exterior walls. Wall / ceiling framing and insulation technically contribute to the overall mass of the partition as well as the resonance and TL calculations, however we don't look to increase the mass of either the framing or the insulation. This is a key point.

*Damping*- The panels used to build partitions are very resonant. This resonance facilitates the propogation (re-creation) of the sound wave. Effectively damping the panels increases TL dramatically.

So in general, as previously posted, mass is king, but it's what we do with the mass that allows us to exceed pure Mass Law calculations. By decoupling the massive leaves, introducing a larger air cavity and adding prudent insulation, we exceed Mass Law calculated performance in the mid and upper frequencies. Again, the answer is not simply mass.

The value of insulation isn't its contribution to the mass of the assembly. Lightweight insulation isn't contributing anything meaningful to the mass of the system, rather it offers absorption within the sealed air cavity. This is why low / medium density insulation performs better in the more problematic low frequencies. Refer to the NRC data as pointed out already. Massive / dense insulation is not what we want at all.

The value of framing isn't its contribution to the mass of the assembly. Indeed, less massive steel studs perform better than wood in a coupled assembly by allowing the panels to flex more. Similarly, 24" OC studs perform better than 16", which are better than 12". Obviously having studs placed 12" OC would yield the heaviest wall, yet the worst performance. Again, it's not all about the mass.

Another example discussed here: The Significance of Air Cavity Depth & the Triple Leaf Effect | Soundproofing Company demonstrates that adding a massive leaf in the middle of a decoupled system air cavity increases the mass of the partition significantly, yet TL performance essentially does not increase.

To Sum: Mass is a critical component of any sound isolating system, however it is the arreangement and deployment of the mass that yields increased results. Stick to a low / medium density insulation, typically exactly what you would use for thermal insulation (Home Depot). THe data says this is best.


----------



## Jewelz (Mar 15, 2013)

To Nestor Kelebay:

Thank you for the scientific explanation! I'm having the same problem, and my upstairs neighbors were actually offering to split the cost but also worried about wasting money on insulation to get no results because it's a floor joist problem. Reading the science behind it has convinced me completely that insulation won't help our problem. I will talk to them about the carpet padding solution instead. Thanks!!!


----------



## Ted White (Mar 15, 2013)

Good Move!


----------



## Owen (Mar 14, 2014)

I'm having the same problem. But my annoyance from my upstairs neighbor is more that I can hear their voices and conversation rather than footstep vibrations. Would green glue and additional layers of drywall be a better option for muffle this acoustic disturbance?


----------

