Soundproofing Basics

If you are considering a soundproofing project from a 30 story hotel to a bedroom in your home, chances are that you have done some research and are feeling a bit overwhelmed and confused about what really works and how many options you have.

This article is intended to give a clear and concise understanding behind the science of soundproofing coupled with the most popular and cost effective sound deadening solutions. We will keep it short and to the point - if you would like more in depth information just browse our soundproofing articles on the sidebar. We suggest that you read through the entire article once before clicking any links.

How To Stop Sound

Sound is a form of energy that travels as a wave - when that wave hits a barrier as in a sheet of drywall, that barrier will vibrate and cause the air on the other side to vibrate, thus transferring the sound through the wall. There is no one-shot soundproofing technique that will stop noise in its tracks, rather we try to employ a combination of solutions to achieve solid performance.

The four most important elements of soundproofing are:

  1. Absorption
  2. Damping
  3. Decoupling
  4. Mass

Absorption can be achieved by installing fiberglass of R-11 in 2x4 walls and R-19 in 2x6 walls and ceilings. Although fiberglass is not a major player, only adding 3-4 points, it is still a step that should be done in any serious soundproofing project. [Read more on insulation soundproofing].

Damping is the process of turning your barriers (drywall, sub floors) into dead panels that do not vibrate, thus preventing sound from passing through them. Damping is achieved by applying a damping compound in between two constrained layers.

Decoupling is meant to separate the attachment of walls from the studs, thereby breaking the direct path of sound, which can be done using resilient channel, and more importantly - with resilient sound clips. This decoupling technique actually adds another component called resilience to the walls. [Click here for an in depth explanation to decoupling ].

Mass simply means creating a heavier wall by using more (another layer) and/or thicker material.

Which Soundproofing Materials To Use

A damping compound is a must on every soundproofing project. The highest performing damping compound is Green Glue Noiseproofing Compound, which can reduce up to 90% of your noise issues alone, and it's performance at low frequency ranges (below STC testing) is remarkable.

There are 3 major players in the resilient sound clip market. Whisper Clip outperforms it's competition by 2-3 points, costs less and is easier to install, saving costs on labor.

At Trademark Soundproofing, we have installed and sold thousands of square feet of sound proofing material. We can confidently tell you that aside from the third party test results, our actual field installation and consumer feedback has shown that Green Glue products outperform any similar products by far.

Creating The Sound Proof Wall, Ceiling and Floor

Walls and Ceilings: The best performing walls and ceilings should be done by installing Fiberglass, Whisper Clips, Hat Channel with 2 layers of 5/8 drywall damped with Green Glue in between.

Excellent results can still be achieved on Walls by just using the fiberglass insulation and 2 layers of drywall with Green Glue on both sides of the wall. This should be given special attention in hotels and multi-family projects, where a double layer of drywall is already in place due to fire rating of the walls. Therefore, it is extremely cost effective to just add a layer of damping compound and achieve solid sound deadening performance.

Floors: For excellent performance, floors should be done in the following order. Floor Joists, Insulation, Gasket Tape, Sub Floor, Sound Board (fiber board), Green Glue and a 2nd Sub Floor. The Ceiling underneath should be done as described above, if possible.

Existing Walls and Ceilings: Additionally, you can install another layer of drywall with Green Glue in between, on existing walls and ceilings. For better results, it can be done twice (double up). This is really one of the only options available when dealing with existing walls. For more details see our article Soundproofing Existing Walls and Ceilings.

One important soundproofing tip to remember is to always seal your perimeters and electrical boxes, etc. with a high quality acoustical caulk.

Doors: Doors and windows are weak links in any sound proofing project, fortunately you can still have a decent door at an affordable price. The simplest solution would be to use our custom cut Sound Control Door Panel. If you would like to use your door on its own then follow these tips. Use a solid wood door, if looks are not an issue install a layer of drywall or wood over the door with Green Glue in between (try getting a flat door). Use proper Door Gasketing and a Door Bottom to seal the door completely. As doors have gaps on the sides and bottom sealing is very important when dealing with doors. Before you put your molding up stuff the gap between the door and wall with foam or sound proof rubber. For more info see this Door Soundproofing Article.

What To Avoid

  • Do not place resilient sound clips and/or channels over existing walls, as this will cause what is known as the triple leaf effect.
  • Factory damped drywall is very expensive, more difficult to hang and does not perform as well as the Green Glue damping compound. The reason for that is simply because Green Glue is a better compound and is installed in a heavier wall.
  • Soundboard and/or resilient channel in walls and ceilings do not perform up to par, as anyone who has installed them can attest to. You will get just as much or more by installing another layer of drywall.
  • Expensive floor underlayments are also a source of post customer complaints, avoid them and use cheap sound board for better results, get the most out of your floors by adding Green Glue in between, as stated above.

How Is Noise Tested?

Let's take a look at a very popular term called STC (Sound Transmission Class) which is an industry standard to calculate sound transmission through barriers. Many building codes now require condos and townhouses to meet a STC of 50, luxury hotels and condos should be looking to reach 60 and higher.

STC Performance Description
20-25 Very Poor Low speech audible
25-30 Poor Normal speech understood
30-35 Fair Loud speech understood
35-40 Good Loud speech heard, but hardly intelligible
40-50 Very Good Loud speech heard faintly
50-60 Excellent Loud sounds barely heard

A standard 2x4 wood stud wall with 1/2" drywall has an STC of 32. An important point to keep in mind is that STC testing only tests on frequency ranges from 125 - 4000 Hz. One problem with this type of classification is that a lot of the common noise issues are due to sounds that fall below or above this range. Examples of such sounds are bass drums, deep male voice, trucks, etc. - all of these can start at 50 Hz. High pitched female voices, shrill ringing of phone and auto horns are good examples of sounds that reach above the 4000 Hz range.

This will explain why many big projects, after having paid tens of thousands of dollars for acoustical engineers and getting thousands of pages of tested soundproofing materials with lab testing of STC of 50 and above, still receive complaints for poor acoustical performance. Just look at this long list of sound complaints from seasoned hotel travelers.

For good measure we will add one more reason for poor performance results: the fact that although material can test to a STC of 25 for instance, does not mean that when added to a wall assembly of 32 (like a standard 2x4 wall) that the end result will be a STC of 57 (25+32=57). In reality, it may only add 2-3 points to the wall bringing it to a STC of 35. A perfect example of this phenomenon is the much touted Mass Loaded Vinyl and all the other brand names that it is sold under.


Here at Trademark Soundproofing, our results are based on actual field installations and customer feedback. As you can see, the basics are simple and straightforward with less cost than you might have anticipated. There are some fine tuning details which you can still pick up by browsing our site or by contacting one of our friendly associates.

When you are ready to begin the actual process of sound proofing click on our soundproofing 102 How to Soundproof article, for detailed instructions.

© 2009 by Trademark Soundproofing

Customers Questions and Answers

1) KJ: Hello, I have a question that I cant find an answer for anywhere, I am constructing a recording studio and was wondering if the decoupled wall I will be building between the control room and the live room should have resilient channels on both sides or will this increase wall resonance as it will makes the wall more springy (note: the mass on either wall face will have different density so to avoid resonant frequencies that might be sympathetic to both sides). Also should the insulation be touching off each other from both decoupled walls in the air cavity or does this compromise the whole idea? ... Thank you for your time.

Trademark Soundproofing Reply: Hi KJ, Decoupling one side is enough. The 2nd side will not add much. Fiberglass insulation can touch the walls and will not create any coupling (contrary to the myth).

2) Mike K: Hi - I recently built a 50' x 75' pre fabricated steel building, primarily for a garage, but I was also looking to use it for some small groups of friends for some loud nights listening to some tunes, but do not want to disturb the neighbors. The building is set on 4' high 10" thick poured concrete stem walls. I am in the process of selecting my insulation and thermal barrier (most likely drywall), and wanted to see about the best way to go about minimizing sound transfer to the outside. The nearest neighbor is about 200' away. Can you guys help with design and material?

Trademark Soundproofing Reply:

Hi Mike, If you have wall and ceiling studs there and that distance you can probably go with insulation in the walls and ceiling and double drywall with Green Glue damping Compound. You can see more details here

3) John B: Which is the most effective sound barrier - 1) Mass Loaded Vinyl or 2) two layers of drywall with green glue in-between? If I use both will the sound reduction double, so to speak? I read all sorts of info on your web site for using green glue, but could not find anything on when to use MLV Thanks for your help

Trademark Soundproofing Reply: Hi John, Double drywall and Green Glue is more effective. many customers use both, MLV, Drywall, GG, Drywall. It will rarely if ever double the soundproofing. It will add some 3-4 STC points.

4) Suzie K: We have built a new house and the wall between the master bedroom and the great room where our TV is has no insulation. It sounds like the TV is in the master. You can actually hear words. I wanted to know if applying mass loaded vinyl on top of the existing sheetrock (in bedroom) then covering that with sheetrock would provide a high level of soundproofing?

Trademark Soundproofing Reply:

Hi Suzie, It would help. "High level" depends on your expectations. If you will be covering with another layer of drywall which will require you to spackle tape and paint then you may want to do it right the first time. By removing the existing drywall and installing insulation in the wall and then you can do either. MLV, Drywall, Green Glue, Drywall. Even better results by using Resilient Sound Clips, Drywall, Green Glue, Drywall.

5) Jay W: I am considering building dual stud walls for a bedroom and bathroom. I want a plywood layer (1/2 - 3/4) in the walls so I can use screws to attach shelves and wall hangings. I already have unfinished 2x4 or 2x6 walls around the perimeter of each room. I was going to use 2x4 framing next to existing framing, with ceiling and floor plates 1 inch from existing plates. This would give me wall cavities of 8 and 9 3/4 inches. If I used plywood and two layers of 5/8 drywall, would I be better to use: Stud-Ply-Dry-Dry or Stud-Dry-Ply-Dry I was planning on using Green Glue between at least the outer two layers. I could also use GG between each Ply/Dry layer. Do you think it would be cost effective? I planned to use 3.5" insulation on each side leaving a 1" airspace between the 3.5-3.5 walls and 3" between the 3.5-5.5 walls. Is it ok to leave these air spaces or should I fill them with additional insulation? I know that I could improve my STC by using metal studs and may do so. Since I will have dual studs, I don't think I will need isolation clips/hat channel. Is that correct thinking? I know I could decrease my wall thickness using hat channel. I could get an equivalent decrease of the total wall width amount by building the second set of studs sideways (1.5 vs 3.5"). Wouldn't this double stud wall configuration still perform similarly or better than a single stud wall with isolation clips?

Trademark Soundproofing Reply: Hi Jay, Stud-Ply-Dry-GG-Dry Using the GG between the first 2 layers as well will give you about 4 STC points (vs 9 points when using it the 1st time). You can use 5" fiberglass. If the 2 walls are fully decoupled you do not need the clips and channels. Sideways would decouple just as well.

6) kim : We are looking to sound proof a gymnasium block wall next to classroom walls in a school - new construction. What method do you recommend with which products? Thank you!

Trademark Soundproofing Reply:

Hi Kim, Can you add to the block wall. I.e. resilient sound clips,channel double drywall and Green Glue. Otherwise you can cover your wall with Mass Loaded Vinyl and cover the vinyl with acoustic panels.

7) Joyce A: Why can we hear people walking and chairs moved and other noises through this soundproofing system? We were told there would be "no noise issue" when we moved into this 3 story building. Ceiling to neighbors floor above. 1 Two layers of sheet rock attached to sound channels. 2 Sound channels attached to floor trusses (drywall not screwed directly to floor truss) 3 22inch deep floor trusses filled with blown in insulution 4 3/4inch OSB floor sheathing 5 1 1/4" thick gypcrete topping 6 at kitchen, bath and entry 1/4 " sound mat and 1" gypcrete is added 7 floor covering (carpet and pad, vinyl, etc) 8 finish flooring

Trademark Soundproofing Reply:

Hi Joyce. There can be many reasons and without seeing the actual construction we are not in the position to say which one it can be. Among them is: 1) drywall screws penetrating the channels and attaching to the joists. This is very common when resilient sound clips are not used in conjunction with channels. 2)AC and/or pipes running through walls between floors. 3)Soffits in ceilings. These are common, there are other factors as well.

8) Kim: Hi, I have an existing old slat floor that I'm going to put 5/8" OSB over and I'm thinking to do the rubber underlayment between to float the OSB. I think I need adhesive so that the OSB doesn't warp. What do you recommend? Thanks, Kim

Trademark Soundproofing Reply: Hi Kim, There are many flooring adhesives out there that can be used for rubber underlayments. Polyurethane adhesives (liquid nails) are very popular.

9) Noreen P: My apartment on a second floor has bamboo flooring and tile in the kitchen bathrooms and entrance. The women downstairs is complaining to the association etc. Can I have the floor taken up and put something in between to block the noise. Will it be expensive to take up the bamboo and then put it back down with more insulation or should I just go over it with carpet? I am extremely upset and angry.

Trademark Soundproofing Reply:

At this stage the easiest would be to put down carpet with a premium carpet underlayment

10) Ellen T: I live about 50 feet from a Tiki Bar that was just installed a few months ago. It has outside music now and the bass sound coming in my window 5 nights a week is driving me crazy. I have 5 inches of foam and cardboard boxes piled in my window, but still hear it. Please help !!!!!!!!

Trademark Soundproofing Reply:

Hi Ellen. Sorry to hear that. Our soundproof window panel barrier is a better option than foam and cardboard boxes however keep in mind that the sound is coming through your walls/floors and ceiling as well so you may have to tackle all of these together.

11) Zord: What methods are best in soundproofing an existing HT in an one level home? Would removing drywall and reinstalling it with resilient sound clips reach way better results? Although there's the laundry and an office between the HT and the closest bedroom I would like to consider extra soundproofing. In addition, what would help reducing transmission of subwoofer originated vibrations and sounds? I would like adding sound treatment on top of the soundproofing layers. What would be best for that? Thank you.

Trademark Soundproofing Reply:

Yes, clips and channels will give a lot better results. Acoustical panels will help reduce the subwoofer vibrations etc. We have a full line of acoustical panels here.

12) Lavs: We are planning a custom manufactured house, 4 single wide trailers arranged in a square with a 32' center courtyard. Lots of glass, very open. Moving from a strawbale house on our property (to become a gym), great sound/thermal insulation. I want to spec the most thermal & sound insulating walls I can/the factory will do. Would I get better results with 2x4 16" oc exterior walls with a layer of closed cell foam/other? board then plywood, then siding on the outside, and two layers of Sheetrock with green glue between on the inside. Or using 2x6 walls without the foam board on outside? I doubt they would do spray foam. Insights? Things I could try to get them to do? Floor - they said they would do 3/4" T&G sub floor on 2x8 16" oc joists,... what could I request to improve sound control? Do I "need" to? Ceiling - double Sheetrock with green glue? Spec-ing all interior walls insulated. Other thoughts? We live on 10 acres, but our corner is a truck route corner,... so that is the sound we want to control. Jake braking and acceleration. Thanks! Happy Holidays!

Trademark Soundproofing Reply:

For sound control purposes we do not recommend spray foam.Double layer of drywall and GG on the inside walls AND ceiling is a very good idea. See here on best ideas on how to soundproof floors.

I always like insulating all interior walls as it helps and allows you the option to add more soundproofing later on.

13) Ed T: If you have two elements side by side, is there an easy way to evaluate the combined STC performance? For instance, if an opening has a glass door (60% of opening) has 17 dB reduction and a fixed sidelite (40% of opening) has 30 dB reduction. How can you figure out the combined net performance?

Trademark Soundproofing Reply: It is very difficult if not impossible to get correct measurements when testing side by side as there are flanking sounds etc. Each item would have to be independently tested in a lab environment.

14) Monica B: I am creating a sound proof basement room for my drummer son. I have installed MLV on ceiling and walls. Do you recommend the I use green tape on studs then two layers of drywall with green glue in between and or should I use clips/resilient channel and then drywall?

Trademark Soundproofing Reply: Hi Monica. Clips and channels are way way better than the tape and if you have the choice than use them.

15) Thomas M: We are expanding a dance studio in a plaza and will be sharing a wall with a pharmacy. They are concerned about the music. The wall is 18'x31' and is metal 2x4 studs with fiberglass insulation and 5/8 drywall on both sides. It is exposed during renovation and will have a suspended ceiling at 10' with 8' mirrors covering the wall. The music is somewhat loud. Your advice would be appreciated. Thanks Tom.

Trademark Soundproofing Reply:

Hi Tom. The first important step is to make sure that they build the drywall wall all the way up to the ceiling the full 18 feet and that it is properly sealed at the top and bottom. Best way to construct the wall is to use resilient sound clips and hat channels on the studs first and ten double drywall with Green Glue Damping Compound on the channels. Otherwise 3 layers of drywall and 2 layers of Green Glue in between. Foe more help you can give us a call 845-388-1200.

16) Vikram K: Hello, We have a Huge Classroom of about 40 feets * 20 feets. Now we want to divide it in two smaller rooms each of 20 feet * 20 feet for making it into 2 classrooms. What will be the best suitable material for making this partition. We were thinking of using two layers of drywall with a Twiga Insul. ( Thanks a lot for the information.

Trademark Soundproofing Reply:

You have to insure that the partition goes fully up to the roof line and is sealed there with a proper acoustical caulk with no nets and/or pipes going from one room to the next. You can then use standard insulation in the walls and double drywall with Green Glue damping compound in between the 2 layers on both sides of the wall. Better would be if one side was decoupled using resilient sound clips and hat channel. One school we worked with actually removed one wall to redo it this way as the results were not as good as the other rooms they had already treated with the decoupling method.

17) Christine H: Hi- I am looking for some advice. I live in an 1850's brownstone bldg. My contractor is advising me to insulate my floors with cellulose and then layer with subfloor and a finished floor on top. I have limited height issues. I also have a toddler and want to reduce the sound of jumping on the neighbors heads. I think I should use some kind of sound mat but I understand it only works if it is sandwiched bet 2 subfloors, which would bring me over in terms of floor thickness. Do you have any advice for me? I thought about green glue joist tape, but they referred me to you. Thanks!

Trademark Soundproofing Reply:

You can use a rubber underlayment with a laminate floor over it. If you are using carpet use the premium carpet underlayment. Either way a good idea to start with the cellulose and joist gasket tape between the joists and first layer of subfloor.

18) Tyler A: Is there an advantage of adding a third layer of drywall? Does it make sense to pay extra for expensive "soundproof" dry wall or just use normal?

Trademark Soundproofing Reply:

Every layer adds additional soundproofing however it diminishes. I.e. the 2nd layer will add more than the 3rd, the 3rd more than the 4th. If you are using the Green Glue Damping Compound than you can use normal/standard drywall.

19) Inga: My question is about calculating sound insulation level in the room. actually how it works? you mentioned that if the STC is between 50-60 you would bearly hear loud sounds. how should we reach 50-60? does it mean that only walls should reach such level or doors, windows, floor and ceiling insulation rates are sum together (e.x. wall 32 + door 27+ carpet flooring 25) and thus reaching 50-60?

Trademark Soundproofing Reply: Hi Inga. No it is not the sum. It is each individual partition tested on it's own. So if you have a wall that you are testing how much sound passes through it it can have in example of 50 STC however if you test that same wall with a plain window built into it than that wall when tested will have a much lower STC as the window will allow more sound to pass through.

20) Lew D: Hi, I need some advice re soundproofing. We have a 2800 sq ft area used as a conference room and banquet hall which is above another large open area. The level of impact noise into the area below is unacceptable. The floor appears to be 2 inch concrete (cast onto some type of metal support surface) covered with ceramic tile. I am considering covering the ceramic tile with a floating floor consisting of a layer of soundboard and two layers of 5/8? OSB and green glue, and using acoustic caulk around the edges. I am not sure of the best configuration for the sound board and the OSB. My first thought was to sandwich the soundboard between the OSB and use green glue on each side of the soundboard. Will this approach give any relief from the impact noise? Should the ceramic tile be removed? Any other suggestions would be appreciated. Thanks, Lew

Trademark Soundproofing Reply:

Your first thought is a very good one. The other option is to use a rubber underlayment on top of the ceramic til and 2 layers of OSB with Green Glue in the middle on top of the underlayment.

21) Chris C: Greetings, Currently my cart has over $600 of stuff in it. Before I spend this money, I'd like your input on my plan. My father lives in our basement, directly below our entertainment area. His TV is quite audible (though muffled) from the floor above. To sound-proof his ceiling, my idea is to remove the current drywall, use hat channels to hold 1 lb MLV to the ceiling joists, and hang 1/2" QR accoustical sheetrock from the hat channels. Is this a good plan to eliminate the sound escaping from his room? Should the MLV be against the QR or the ceiling joists? I am eager for your reply so I can order these items soon. Thank you, -Chris C

Trademark Soundproofing Reply:

Hi Chris. Make sure there is insulation in the ceiling and that you are using resilient sound clips for the hat channel. After that you are good with your plan. MLV can be installed either on the joists or onto the channel. You can also consider doing 2 layers of standard drywall onto the channel (only) with the Green Glue in between them.

22) Chris: Thank you for the quick response. I like your company more and more. I've done more research, and now I'd like to know if it would gain much sound deadening to use the MLV as opposed to two layers of 5/8" sheetrock with greenglue between them? I will be using the hat channels and sound clips, for sure. Really I'm trying to determine if the MLV is worth the time and hassle. Mostly the sound we hear is muffled TV voices or the radio talk (NPR), so not much in the way of lower frequencies. Eager to order this stuff, -Chris C.

Trademark Soundproofing Reply: Thank you. Green glue with 2 layers of drywall is the better way to go. As you will be adding mass with the double layer plus achieving damping with the green glue.

23) Andrew B: Hello. We're having a custom RV designed and would like to soundproof the bedrooms to the outside world. We have exactly 9 inches to work with - and I'd like to know how to make the absolute most of every inch to block as much sound as possible. Cost is not an object. Inch by inch of thickness - is it more effective to use soundproof drywall layers, or something like very heavily packed cellulose? Or does this call for several different methods to cover a wide range of frequencies? Thank you for your assistance.

Trademark Soundproofing Reply:

Several methods. 3-1/2" of framing with insulation another 1-5/8 for resilient sound clips and hat channels and another inch for double layer of drywall with Green Glue sandwiched in between. Seal with acoustical caulk. On all walls and ceilings and you will have great soundproofing.

24) Jenna N: I have a fitness center located in commercial building next to a chiropractor. The current wall is 61ft/15ft with 4 inches of insulation standard pink batting. I was thinking the solution is putting a mat under all the weights and to inject foam in the 4" wall then add additional layer of hard foam closing up with an 2 layer of sheetrock 1/2" what would you recommend?

Trademark Soundproofing Reply:

Don't inject any more foam to the existing insulation (you will be wasting your money. Adding a 2nd layer layer of drywall is a very good idea, sandwich the Green Glue Damping Compound Tubes between the 2 layers to really enhance the soundproofing performance. If you have a drop ceiling with an air space above the wall than you must soundproofing the ceiling too. I suggest you use the ceiling tile barriers.

25) Lisa C: We have an office building with a dropped ceiling, we use standard Radar USG, 2x4 tile. We have tried adding a layer of drywall to the ceiling tiles but it does not help that much. Would it be better to double up on the ceiling tiles instead. They seem to have a higher NRC rating.

Trademark Soundproofing Reply:

Hi Lisa, Please see this video

26) Alfonse: Do I definitely need insulation? Everyone treats it as a first step, but the consensus seems to be that it doesn't actually do a lot. This is for ceilings and walls in a wood-frame attached townhouse with 2 apartments. I'm thinking of starting with insulation (there is none currently) but I wonder if I should skip that step and go right to the Green Glue and extra drywall, since that seems to be the most effective low-cost route.

Trademark Soundproofing Reply: You should definitely start with that.

27) Paul D: We are designing a movable partition wall for a dance studio that would transform one 40' x 40' x 10' tall room into to two 20' x 40' rooms. We are considering constructing the panels out of drywall with green glue. Presuming that we do a good job of sealing the edges, what STC can we expect with the following constructions: 1/2"DW/GG/1/2"DW, 5/8"DW/GG/5/8"DW, 1/2"DW/GG/1/2"DW/GG/1/2"DW We want to minimize panel thickness to simplify the mechanism for moving the panels so hollow core stud walls won't work for us.

Trademark Soundproofing Reply: There is no lab testing that we can reference that has tested Green Glue without it being on a stud wall. The 3rd configuration would work best and should give you an STC in the high 30's range.

28) Tony M: Hello, hoping you can help with a soundproof question. I have a double storey house, and will be renting the lower level. The floor on top level is pine boards on joists, no subfloor. There is already a drywalled ceiling in the lower level, with old and thin insulation above it in-between the joists. Is it best to keep this ceiling and soundproof below it with the methods you offer (sound clips, resilient hats, drywall, green glue, drywall), or should I tear down the ceiling, properly apply insulation in the joists, then do the rest of the process? Thanks!

Trademark Soundproofing Reply: Best to tear down the ceiling. This will allow you to re insulate and properly decouple. Decoupling on an existing layer is not recommended if there is the possibility of decoupling from the joists themselves.

29) noah s: Hi, I am building a sound isolating wall between two living spaces in a duplex. I'm wondering about what would be a preferable construction. I'm going to use two layers of 5/8inch drywall with green glue on one side of a 2x4 insulated wall and I was wondering if I'd get better results with either hat channel with clips or a staggered stud design with the drywall attached to that. Let me know what you think. Thanks.

Trademark Soundproofing Reply: You would definitely be enhancing your soundproofing significantly by doing that. As you will be adding the additional component of decoupling as well. Clips and channels is the better of the 2, however if you plan on hanging heavier items from the wall than go with the staggered studs.

30) Margie: I'm renovating my 1200 sq ft office condo by expanding into the adjacent condo. Some walls will be partially replaced with soundproof glass. Ceilings are 9 feet. What floor covering should I use to minimize noise? I'm interested in a vinyl wood look alike. Should I go with carpet instead?

Trademark Soundproofing Reply: Carpet is definitely a lot better at absorbing sound and footsteps. The plusher the better.

31) Jason M: Soundproofing a basement located home theater / music rehearsal room. Began as 18x18 ft single stud (16”) frame. Added a fully decoupled interior room with 20” studs and 1 inch air gap. Floor beams of interior room are nailed into the slab with no other dampening. Will double 5/8 on exterior wall, r15 pink insulation, and then whisper clips/hat channel with another double 5/8. Green glue throughout. Ceiling is also decoupled both frame and drywall. Swapped aluminum duct work out for flex in returns (with cannot he moved), cut off other supply ducts and removed. Have one supply and one return in new room. My questions: 1) should I treat the floor other than 2x plywood and carpet? 2) will HVAC above and inside be a problem? 3) what is best way to mount fixtures to interior decoupled wall? Snap toggles or right into hat channel? I know I don’t want to attach anything to interior room studs because it will short circuit it. 4. For outlet panels, lights, etc, just sink then into double 5/8 drywall with some puddy on back? Thanks!

Trademark Soundproofing Reply:

Good job! That should be sufficient for the floor. HVAC is always a pain when it comes to sound as it is designed to allow air flow. You can cover the top and sides of the vent with some Mass Loaded Vinyl. If it is a light weight fixture you can go direct into hat channel. Light/electrical boxes are usually mounted to the studs with Putty Pads wrapped around them.

32) Travis T: Hi, I am looking to construct a window plug for a large, 72" by 31" window. I am looking to use a one and 1/8 inch compression barrier with an STC of 34 for the first layer-(facing window- cut slightly LARGER than the exact dimensions of the window well- then use a one inch MDF or OSB (cut slightly SMALLER than the exact dimensions of the window will- as the outward facing material. The compression barrier features a PSA backing. If the MDF has an STC of 30- Using these two panels, does my installed window plug build now have a 64 STC? Any other suggestions for maximizing STC for this project? Cheers, Travis, Montreal

Trademark Soundproofing Reply:

Hi Travis. No. The 2nd layer will only give you about 3-4 STC points. You can use 2 layers of half inch MDF or OSB with the Green Glue damping Compound in between to give your plug a boost.

33) Sherwood S: My condo has ceiling fire sprinklers. Does that present an additional problem?

Trademark Soundproofing Reply: That is an issue but keep in mind that nearly all soundproofing projects in the "real" world have issues such as piping, lighting, duct work etc. That being said fire sprinklers are not that bad just be sure to caulk around the edge to ensure a tight seal.