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Soundproofing a Ceiling

crazycorms's picture

Hi All,

 

I need advice on sound proofing a ceiling in a first floor apartment.  The unit is currently occupied and both the above and below tenants are complaiing about noise.  I know the ceiling isn't insulated.   What else can I do to dampen the noise?  A couple of notes on the issue:  The joists are 2x10 16 oc.   The above unit has hardwood flooring with no sound barrier undeneath.  I want to fix the issue with as little disruption of the tenants lives as possible.  at this point in time I am thinking about insulating between the joists and using a drywall product called Quietrock 525, 5/8" thick.  Thanks in advance, Mike

When building my house w/ a (post #186996, reply #1 of 37)

When building my house w/ a second future unit in the basement, I built to code ... which required fire rated separation of the two units AND a code required (i.e. sound rating) on the adjoining walls/ceilings. I learned a fair amount about codes and sound ratings. The gypsum association has a number of details that meet the code required sound rating (STC - sound transmission coefficient, although I forget the key values). I think you might find a number of details online on various drywall details that have various STC ratings. You should have a dozen choices that you can choose from to help your situation.

One method:  use 'hat channels' attached to perpendicular to joists and then one or two layers of drywall.

A few basics about sound transmission ... it is reduced by 1) insulation 2) separation/isolation of direct paths of sound transmission, and/or 3) the presence of mass. Carpet/insulation helps, the hat channel helps, and multiple layers of drywall helps.

There ain't NO free lunch. Not no how, not no where!

Soundproofing (post #186996, reply #3 of 37)

Thanks for the quick response.  I am going to continue my research and look up these codes in the morning.  Thanks Again.

Blowing cellulose into the (post #186996, reply #2 of 37)

Blowing cellulose into the ceiling will help a lot.

Beyond that, more rock, and the isolating channels.


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

DanH,   Have you done (post #186996, reply #4 of 37)

DanH,

 

Have you done this before?  How did you effectively blow the insulation without and incredible amount of holes in the drywall?  Is there a tried and true method to this practice?  Thanks, Mike

Haven't done it before, but (post #186996, reply #5 of 37)

Haven't done it before, but have been in homes where it was done.

If you're gonna be installing more rock the holes aren't a big deal.  Controlling the mess is a problem, of course, but a manageable one.


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

You've got some good advice (post #186996, reply #6 of 37)

You've got some good advice already.

The obvious immediate fix is to put an area rug with an underlay on top of the upper hardwood floor and make sure there are no holes between the units (light fixtures etc ?).

White noise generators (or fans) can be used in the bedrooms to mask ambient noise and make it easier to sleep.

We used to use resilient metal strapping instead of the "hat". It as the name suggests has some flexibility.

IIRC oddly enough it was recommended that the ceiling cavity sound reduction was more effective if only partly filled with insulation.

Insulation least effective means of reducing sound transmission. (post #186996, reply #7 of 37)

Mass is effective.  More drywall thickness means more mass.  Just screwing on another layer, over what is there, is a quick fix that will bring results.

Solutions requiring demolition:  Remove upper floor finish, put down something like Sika Acoubond foam layer, put new floor on using Sika glue system.  Remove existing drywall on ceiling below, do strapping with RC (resilient channel) steel, do one layer of 5/8 QuietRock.

Least cost fix might be the carpet and dense underlayment, already mentioned.

 

"A stripe is just as real as a dadgummed flower."

Gene Davis        1920-1985

Leaving the ceiling rock (post #186996, reply #8 of 37)

Leaving the ceiling rock would be, I would think a good idea even if you use the RC channel and another layer of rock. Like you say ... more mass is good. And adding an RC channel and rock w/out demo'ing the existing ceiling seems easy to me.

There ain't NO free lunch. Not no how, not no where!

Mass, stiffness, damping, and (post #186996, reply #9 of 37)

Mass, stiffness, damping, and sealing off leaks.  And eliminating resonance.

Which is most effective depends on the structure and the nature of the sound.  High frequency is easier to kill than low frequency, but sometimes killing off the higher frequency sounds makes the problem worse, because all you're left with is the booming, like the car next to you in traffic with the subwoofers.  (Loud voices are more irritating if the higher frequencies are suppressed.)

Eliminating resonance means preventing the structure from having a single resonant frequency anywhere near the frequency of the offensive sounds.  In some cases, eg, it might make sense to only plate 2/3rds of the ceiling with extra rock, so that the different sections resonate at different frequencies.  But that gets into some advanced stuff.


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

Without question, the best (post #186996, reply #10 of 37)

Without question, the best results will be obtained by removing the ceiling drywall below. A few general comments:

 

Insulation will do little.

 

Resilient channels cannot be applied to the existing drywall. The newly created small air cavity will severely limit any improvement.

 

http://www.soundproofingcompany.com/solutions/soundproofing_ceilings/  This article gives an understanding of what you're up against and some potential solutions.

Ted

 

Soundproofing Company

I was doing a bunch of (post #186996, reply #11 of 37)

I was doing a bunch of searching online and found this thread-

http://www.avsforum.com/avs-vb/archive/index.php/t-1017460.html

In this AVS thread you seem to advocate standard pink insulation as the best value for soundproofing. Am I misreading this? Please explain, as I am going to be facing this exact problem within a few weeks. In your opinion, what is the best value for soundproofing a ceiling with another floor above it?

I was doing a bunch of (post #186996, reply #12 of 37)

I was doing a bunch of searching online and found this thread-

http://www.avsforum.com/avs-vb/archive/index.php/t-1017460.html

In this AVS thread you seem to advocate standard pink insulation as the best value for soundproofing. Am I misreading this? Please explain, as I am going to be facing this exact problem within a few weeks. In your opinion, what is the best value for soundproofing a ceiling with another floor above it?

In a sealed cavity, the (post #186996, reply #13 of 37)

In a sealed cavity, the inexpensive fiberglass used for thermal insulation does about the best job. Just don't over-compress.

Ted

 

Soundproofing Company

take down ceiling (post #186996, reply #14 of 37)

a company called serious building products has the tricks u need. there are clips that screw to the joists with rubber grommets, these hold steel furring channels. they have a sound absorbing glue that is applied between double layer of drywall on these furring strips and the sound is cut down immensely

Serious materials makes quiet (post #186996, reply #15 of 37)

Serious materials makes quiet rock, which is a great product. They have acoustic test reports available. Their product is simply a pre-damped drywall, using the exact same drywall you can buy locally.

Any pre-damped drywall is simply layers of standard board 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.

Ted

 

Soundproofing Company

Gypcrete isn't available (post #186996, reply #16 of 37)

Gypcrete isn't available here, so we went with a layer of DW, a layer of donnacona, rez bar, and R20 FG betweeen the joists. (Donnacona is that cheap lightweight particle board. It may have a different name where you are).


It works reasonably well.

I would have used a moderate (post #186996, reply #18 of 37)

I would have used a moderate amount of construction adhesive between the layers.  Creates a damping diaphragm, kinda like what we did for aircraft back when I used to test rubbers for the Air Force.


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

Resiliently attaching the (post #186996, reply #17 of 37)

Resiliently attaching the drywall to the joists is a great idea. You've created a spring. Now the trick is to lower the resonance point of that spring. We do this by weighing down the spring (adding mass). The more the better.

So in this case, substituting the lightweight panel for a second sheet of drywall would have improved performance.

Ted

 

Soundproofing Company

Construction adhesive has (post #186996, reply #19 of 37)

Construction adhesive has very little if any damping properties. Silicone doesn't benefit us either.

Ted

 

Soundproofing Company

It's not the damping (post #186996, reply #20 of 37)

It's not the damping properties directly, it's the viscoelastic properties.  Two (or more) membranes with viscoelastic adhesive between provides significant damping -- they use the concept in military aircraft.

I'm sure construction adhesive isn't the IDEAL adhesive (I spent a year in college testing different ones for this job), but it's in the right general ballpark.


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

This is interesting, however (post #186996, reply #21 of 37)

This is interesting, however we need to be careful to give the OP and others the right practical information when looking to increase the sound isolation for their walls, ceilings and floors. Having been on the R&D side of damping materials since 2003, I can tell you that standard construction adhesive is far too rigid to effectively damp vibration in drywall and plywood. Silicone is also too stiff and elastic. This is why walls independently tested in certified NVLAP acoustic labs have found that neither is suitable for acoustic purposes, and why they are never incorporated into competent sound isolation designs.

What we're talking about is Constrained Layer Damping. Two mass layers with a Visco-Elastic layer in between. The vibration travelling through the mass layers (as a bending wave) create shear forces on the damping layer, creating friction and heat. This heat is the result of the energy conversion from kinetic to thermal. This lost energy directly relates to increased Transmission Loss.

The damping layer can be optimized (adjusting the viscosity and elasticity) depending on the frequency range in question as well as the thickness (stiffness, actually) of the mass layers. I can certainly appreciate why a damping layer between rigid aircraft metal might require a higher stiffness than traditional construction damping materials. Damping drywall would reasonably require a different set of viscous and elastic parameters than damping rigid aircraft aluminum, for example.

Ted

 

Soundproofing Company

Actually, the "rigid aircraft (post #186996, reply #22 of 37)

Actually, the "rigid aircraft aluminum" was thick foil.  And I was only saying that it wouldn't have hurt, and might have helped, to use a (relatively flexible) adhesive between the two layers described in the referenced post.  Not saying that it would solve the OP's problems.


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

green glue (post #186996, reply #23 of 37)

quiet rock has a green glue , much like acoustic sealant, that stays rubbery forever, i stepped on drop of it a week after we finished taping and it stuck to boot like flubber. thats the kind of material u need to dampen or dissipate the sound

With all due respect "we" (post #186996, reply #24 of 37)

With all due respect "we" don't need to do anything ... but share the knowledge (we think) we have. Your tone doesn't quite come across right. You simply have to state your kowledge and maybe some words that give the reader confidence that you know what you are talking about (e.g. I've been doing this for 40 years or explain the science so they understand it).

Silicone is to stiff AND elastic? Sound contradictory. How can it be both?

Nice of you to share your stuff with the rest of us. I learned a little.

There ain't NO free lunch. Not no how, not no where!

Without boring the larger (post #186996, reply #25 of 37)

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, actually. The panel materials are standard (Home Depot-type) building materials. Spread between these layers is a damping compound like QuietGlue, Green Glue, Swedak, DecibelDrop, etc. Calcium Silicate? ... That's cement board...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).

Data: http://www.greengluecompany.com/greenGlue-vs-FactoryDampedPanels.php

This independent data is from Orfield Laboratories, a fully NVLAP certified Acoustics lab.

As I have said before, generally you will always be able to field assemble a more massive, more damped and significantly less expensive wall or ceiling. An additional plus is that field assembly will allow you to overlap seams between the drywall layers. 

Ted

 

Soundproofing Company

Similar situation (post #186996, reply #26 of 37)

I don't wish to hijack the thread, but I have a similar situation and could use some input.  I am remodeling an old building, converting the main floor into a coffee shop, and the upstairs into an apartment for the owners. You can see the progress and what the project looks like at www.project114ok.com for reference.

I've replaced the original joists with 14" i-joists and will be installing the original tin ceiling below the two layers or 5/8 firerock.  I'm trying to ensure sound transferrence won't be an issue.  I've looked at several products and had come to the conclusion that Green Glue between the layers of firerock was more effective and cost less than using a layer of mass loaded vinyl between the joists and rock. 

Upon further investigation, it seems that using sound clips and hat channel will be more effective than Green Glue.  My concern stems from wondering how well the clips and channel will last over the years.  As a someone who renovates and remodels older buildings, I strive to ensure the work I do will last at least another hundred years or more along with the building. 

I try to do work that will only need to be changed if someone decides to remodel down the road, not because of failure or maintenance required. 

Having not had the chance to works with sound barriers, it is difficult to know how good a product is until I try it and I want to make the best decision I can based upon as many sources of information I can find.  If anyone is aware of other product options that may work as well or better, please let me know. 

Please check out the website.  See the layout I'm talking about.  The sound barrier will be on the ceiling to the rear vertical firewall.  I haven't put up the two layers or 5/8 firerock on the back side of that firewall yet and want to incorporate sound barrier there as well.

Thank You in advance for any help.

Ott

Hello Ott. Not a hijack at (post #186996, reply #27 of 37)

Hello Ott. Not a hijack at all.

 QUOTE:  " I've looked at several products and had come to the conclusion that Green Glue between the layers of firerock was more effective and cost less than using a layer of mass loaded vinyl between the joists and rock. "

This is true. While the MLV adds very helpful mass, so does the drywall. What you would like is to damp the drywall itself, which MLV does not do effectively.

QUOTE: "Upon further investigation, it seems that using sound clips and hat channel will be more effective than Green Glue."

This isn't quite so linear. The two systems do different things. One decouples, while the other damps. High level isolation systems use all 4 elements available for sound isolation:

  • Decoupling (the clips & channel)
  • Absorption (insulation)
  • Mass (the drywall)
  • Damping (the Green Glue you mentioned)

If you are primarily concerned about noise from below going up, then a suggested application would be:

  1. Install a "one-piece" resilient clip and 7/8" 25 ga. Drywall Furring Channel. This will provide the decoupling you've already determined is effective.
  2. Install R19 fiberglass. Standard stuff, no need for anything that says "acoustic". Also no need to fill the cavity with R30. This provides the absorption.
  3. Install double 5/8" drywall. Standard Type X. No need for exotic board. This provides the mass you need.
  4. Install the damping material you referenced.

This is a classic system that provides a great deal of sound isolation. Tried and true. The materials are all fire-rated. The clips and channel are all solid, primarily galvanized steel.

Ted

 

Soundproofing Company

Thank you for the info (post #186996, reply #28 of 37)

I appreciate your response, it certianly helped me sort out the seemingly conflicting information I had gathered so far.  I always appreciate knowing the science behind a situation, it helps me to find the best approach.  I'd planned on the R-19 already. 

I'm curious about the effect of the tin ceiling in the situation.  Any thoughts, I'd planned on applying 1x2 furring strips to attach it over the sheetrock.  I imagine as long as they're attached to the channel it won't hurt, and the additional airspace may help. 

Conduit will be run between the furring for the lighting.  Is there anything you would recommend to be aware of on the guage, sizing, or spacing on the channel in regards to the additional weight of the tin ceiling etc?

Again, thanks for the information

 

Ott

Hello Ott, Well, here's the (post #186996, reply #29 of 37)

Hello Ott,

Well, here's the thing. In general, adding a second air cavity (created by the furring channel) next to an original air cavity (the fiberglass filled joist cavity) will tend to be counter-productive. Both air cavities will resonate which is generally to be avoided.

There would be no concern if the tin tiles are lightweight (almost like foil). If that's the case, they won't have enough mass to acoustically define second air cavity. So the effect of the tile installation will largely depend on how heavy the tin is. If any more dense / massive than 1/8" plywood, it would technically start to become an issue. Definately an issue if the tin tiles were as dense as drywall, for example (obviously they're not)..

While I think you're just fine, in general you can minimize this effect by:

  1. Not using the furring strips. I realize you had planned to run wire through, but perhaps a dedicated conduit or two would help? If run through a hole in the ceiling, no larger than 1 1/2". You could substitute the second layer of drywall for a layer of OSB. This would give you a constant nail base to attach the tiles. perhaps?
  2. Insulating the cavity. A very thin whispy layer would help a little... but only a very little.
  3. Keeping the finished tin tiles as loose and un-sealed as possible. The less the cavity is sealed, the less it will act as a defined air cavity.

Ted

 

Soundproofing Company

  It looks like as long as (post #186996, reply #30 of 37)

 

It looks like as long as I incorporate R-19, Clips and Channel, and Green Glue it should be as good as I can get.  I think the ceiling tiles should be ok.  It'll be very difficult as it is for to get a good fit since there being reused. 

Would there be any benefit to an accoustical underlayment between the subfloor and hardwood flooring upstairs instead of the Green Glue dampening layer?

And did you have any thoughts on the channel strength and clip spacing?


Now that I have a good idea what needs to happen, the only question remains how to do it in the most cost effective manner.  :-)

 

Thanks again,


Ott