The basic design of the clip is familiar with the black neoprene bumper and one screw installation. The performance increase, which is mainly found in the low frequency ranges, is largely attributed to the quality of the neoprene rubber attached to the clip. The Durometer (hardness) of the rubber is 20 points lower than the other resilient clips that incorporate rubber on their clip. That is a very noticeable difference and just part of the equation that helps the GenieClip perform at maximum efficiency. Here is an excerpt from the manufacturer’s site discussing the quality of rubber on the GenieClip:

Importance of Rubber Properties in Performance of the Resilient Clip Technology

Rubber is a superior vibration isolator. In almost every significant application, rubber is chosen to isolate vibrations because of its compression ratio, dynamic and static properties. The dynamic properties of the rubber element of a vibration isolator are affected by its compression ratio, and thus the dynamic characteristics of a vibration isolator depend on the static load.

Stiffness

The stiffness measures the “spring rate” of the rubber. Higher spring rate means a stiffer material and lower overall performance.

Static Stiffness

Under a static or constant load, the stiffness is measured.

Dynamic Stiffness

Tested under a variable load due to the effect of vibration. It is a forced frequency test for resonance at specific frequencies. Natural rubber has the lowest dynamic stiffness of common material.

Result

KINETICS: 21.6 N/MM
PAC: 21.2 N/MM
PLITEQ: 11.3 N/MM

Dynamic / Static Stiffness Ratio

The ratio is a measure of the resiliency of the material. For example, for completely resilient material, the ratio is
1. In order to achieve isolation at lower frequencies, it is important that this ratio be as low as possible. Therefore, ratio closer to 1 means better vibration isolation performance. Most acoustical engineers will specify isolators that have a maximum dynamic to static ratio of 1.4.

Result

KINETICS: 1.29
PAC: 1.34
PLITEQ: 1.19

Force / Deflection Curve

If the isolator is more resilient, typically the acoustical performance will be better. A measure of force versus deflection gives a direct link to resilience at a static loading.

Result

KINTETICS: 19.79 N/MM
PAC: 23.88 N/MM
PLITEQ: 8.95 N/MM

Durometer of Rubber

Durometer is a term for hardness as indicated by the Shore A durometer number. The normal range for isolation materials is 40 to 60+ / -5 as limited by dynamic stiffness. Steel springs for example have a ratio of 1. Dynamic stiffness increases with hardness and in broad terms, the filler ratio of the materials to the rubber content as well as the carbon black reinforcement, plasticizers etc.

Results

KINETICS: 56
PAC: 57
PLITEQ: 37

Conclusion

Based on these results, the rubber stiffness of the Pliteq GenieClip is about 2 times better than the other two materials. Since the dynamic stiffness and dynamic to static ratio control the performance of the clip, especially at low frequencies, it is clear that the performance of the GenieClip will be superior to the other two products.

The above report can be found by opening up this .PDF file: Importance Of Rubber Properties

What The Above Report Means For Your Project

The increase in performance from the GenieClip is most noticeable in the lower frequencies. The GenieClip provides a 2-3 point increase in the lowest of frequencies compared to the most popular resilient clips. The STC rating of the GenieClip is as high as 64 with an OITC rating as high as 49. The GenieClip’s ability to isolate both high and low frequencies make this clip a great option for any project. The quick one screw installation and low profile design will help you get the job done quick without sacrificing too much headroom.

Acoustic underlayment is used anywhere a higher level of isolation is required in both STC ratings and IIC ratings.  The materials used in acoustic underlayment are usually recycled rubber, cork, a combination of rubber and cork, and foam.  Other underlayment includes adding Green Glue between the existing sub-floor and a new layer of sub-floor or “mass-based” rigid underlayment usually made of concrete type materials.  The higher performing underlayment (rubber, cork, or a combination) are usually required in multi-family housing and other commercial applications to achieve a field test IIC rating of 45+ and a lab test IIC rating of 50+.  Most condominium structures and large commercial buildings use thick concrete floors and steel framing so these ratings are achievable with an underlayment of minimal thickness–typically around 2mm depending on the flooring used on top of the underlayment.  For example, tile floors will require a thicker underlayment as they will generate considerably more noise than a vinyl floor or even a hardwood laminate.

Different Ratings For Underlayment

STC ratings largely cover the higher frequencies like speech, radio, and sounds from the TV (not including sub-woofer).  IIC ratings is a way to calculate the level of isolation in relation to impact noise or structure-borne noise which would include footfall, a chair dragging along the floor, or other common noises typically caused by every day living.  The IIC rating is important because a floor can have a sufficient STC rating, say in the low 50′s, but won’t do much at all for isolating impact noise.  With that said, IIC ratings can be very misleading in most cases because it is a rating for the entire system and not just for the material added to the current construction.  Most IIC tests include several inches of concrete, a layer of Gyp-Crete or similar, and usually an acoustically rated ceiling on the underside including either steel stud framing or resilient channel.  So the solution for this dilemma, to cut through the bogus claims of 70+ IIC is to find out the Delta IIC rating.  The Delta IIC rating, or usually written as ?IIC, is a rating for what the material truly isolates on its own.  Like every sound rating the Delta IIC can be misleading as well as performance of a product on a concrete sub-floor will vary from the performance of a product on a wood floor.

If Many Ratings Are Misleading Then What Should I Do?

Unless you can verify the materials used in a test then you can either trust the person trying to make the sale on the product or educate yourself on what type of materials and methods can actually isolate sound.  For walls and ceilings the best way to isolate sound is to decouple the room you are in from the existing structure as much as possible.  The same is true for floors, but the cost of doing this in floors, at least properly, can be ridiculously expensive.  The next best option is to dampen the connection between the flooring and the sub-floor.  To do this you really only have two options.  You can either use a resilient underlayment or add a layer of sub-floor to the existing construction with a damping glue between the existing sub-floor and the new layer of sub-floor.

Using Green Glue To Dampen

Adding the second layer of sub-floor with a damping glue like Green Glue will definitely provide some great results.  The only problem is that installation can be very complicated and limited to certain floor constructions.  One of the limitations is that you can only properly add a layer of sub-floor and Green Glue to the existing sub-floor if the existing sub-floor is wood and not concrete.  This is because the new layer of sub-floor will need to be screwed into the existing layer of sub-floor so that the Green Glue can properly compress between the two layers of sub-floor.  Another limitation of using Green Glue and an extra layer of sub-floor is simply the labor of installing another layer of sub-floor.  It really isn’t much of a DIY project, at least not for a novice, and can be pretty close to impossible to accomplish in a retrofit situation if you don’t have the space to setup a table saw to cut the sub-floor to fit your existing floor.  So adding a layer of sub-floor and using Green Glue is a great option and can be very affordable in comparison to rubber underlayment if all the labor is done yourself or free by someone else.  SIDE NOTE: Have you ever read a paragraph that used the word ‘sub-floor’ more than this paragraph?

Using Rubber To Dampen

Solid rubber is without a doubt the most resilient underlayment available.  In fact, 2mm of rubber underlayment is equal to 6mm of the next best performing underlayment which is cork.  Rubber underlayment usually comes in 4′ wide rolls in either 25′, 30′, or 50′ lengths and 2mm, 3mm, 5mm, 6mm, 8mm, and 12mm are the most common thicknesses of rubber underlayment.  The advantage rubber underlayment has over Green Glue is that it can be used on wood floors, concrete floors, wherever, and installation only involves rolling out the underlayment and taping the seams together.  You can glue it down, but you definitely don’t have to and really you shouldn’t glue it down if you are using a floating floor on top of the underlayment.  Acoustical underlayment manufactured from sustainable recycled rubber composite, offers optimal sound reduction while remaining impervious to the elements for life.  Unlike natural cork, recycled rubber remains permanently resilient and will not embrittle with air exposure.  Recycled rubber underlayment can be used with most all wood flooring installations, including glued down, nailed down and stapled down.  It is also specified for use beneath ceramic tile, cork floors, carpets and a variety of resilient sheet and tile floors.  As is the case with acoustic cork, whenever you are installing flooring by a method other than free-floating, the underlayment must be attached to the sub-floor as opposed to simply laying it down.

Using Cork To Dampen

True acoustic cork underlayment will provide a high level of sound reduction as long as the cork used is 6mm or thicker.  Acoustic cork underlayment is spec’ed for use under all types of flooring including glued, nailed, and stapled down installations.  With some flooring types (typically hardwoods and hardwood laminates) you may need to install a moiseture barrier under the cork.  Most manufacturers will accept a 6mil plastic sheet as a moisture barrier.  Be sure to consult the manufacturer before installing your flooring over cork without a moisture barrier.

Cork is also a very affordable build-up material that can be used to create level transitions from tile, hardwood, and carpeted surfaces.  As with rubber underlayment, whenever you are installing flooring by a method other than free-floating, the underlayment must be glued to the sub-floor instead of utilizing a free floating installation of the underlayment.

Conclusion

The only effective way to isolate impact noise and reduce sound transmission between floors is to use an underlayment that can properly dampen.  Rubber underlayment will always perform better than the rest and also has several other advantages in regards to longevity and providing a quality moisture barrier.  Cork underlayment is a very cheap product that can perform well as long as you have a really thick cork.  A 6mm cork will only perform as well as a 2mm rubber underlayment, but that may be all you need for your project.

A triple leaf wall is a wall with 2 air cavities, and not just one. Similarly, a quadruple leaf wall would be a wall with 3 air cavities. A leaf in a wall is a solid layer – like drywall – and (if you prefer) a triple leaf wall has 3 leaves, etc. Like this:

Here we see single leaf (no air cavity), double leaf (like most walls), triple leaf and quadruple leaf constructions. It is important to remember that if you use 2 layers of drywall directly against each other, it still only counts as one leaf because there is no air cavity between the layers. In the sketch below we show again single through quadruple leaf walls, but this time they all have the same number of drywall layers.

Why A Triple Leaf Wall Is A Bad Thing?

It is not illogical to presume that the quadruple leaf wall above would have the best sound isolation. After all, the sound has to go through a:

Solid mass – air space – solid mass – air space – solid mass – air space – solid mass

That quadruple leaf wall is decoupled 3 times over! While in a double leaf wall, it has to make it through only one air space, and in a single leaf wall there is no air space at all.

Well, while this makes sense, it is very false, especially at low frequencies. To understand why this is, we have to take a look at how decoupling works. Decoupling isn’t effective at all frequencies. If you take two layers of drywall, and separate them with an air space, it doesn’t improve things at all frequencies. The air in the cavity acts like a spring, and creates a resonance. Only well above this resonance do things improve (but then they improve very nicely indeed). This graph should make the point:

Effect Of Decoupling A Solid Mass

What you see is the sound-stopping power of the wall, in decibels, at different frequencies. This is called “transmission loss”. While this data is hypothetical, this is what occurs in real walls – the decoupling has a large positive effect at high frequencies, but a negative effect around the resonance.

Resonance Must Be Low In Frequency

To attain good low frequency performance, this resonance must be as low in frequency as possible – otherwise the weak point of your wall will fall at an unfavorable location, and low frequency noise will have little trouble passing through the wall.

The goal of any decoupled wall should be to drive resonance down in frequency. To do this you have to:

• Add mass to one or both sides of the wall
  
• Increase the depth of the air cavity
  
• Add insulation (if you don’t have insulation)

Triple leaves are bad because for a given amount of mass and space they always have a higher resonance point than a double leaf wall.

One of the criteria that were given above for getting a low resonance point – and good low frequency performance – was a deep air space, with a lot of mass on either side.

The double leaf wall might have an air cavity depth of 8”, but for the same overall net wall depth, the triple leaf wall’s cavity will be just half that, and the quadruple leaf’s cavities will be only 1/3 of the depth of the double leaf wall.

To make matters worse, each leaf in the double leaf wall is very heavy, but each leaf in the quadruple leaf wall is far lighter – half the mass. This will cause resonance to go up in frequency even more, and low frequency performance will be badly degraded.

Multiple resonances / possibly more severe resonances. To further complicate things, a triple or quadruple leaf wall may exhibit more than one low frequency resonance – and if one is bad, then two or more are surely even worse.

Finally, the resonance behavior of multiple leaf walls isn’t simple or entirely predictable, and may be more severe than with a double leaf wall.

Comparing Single, Double, and Triple Leaf Walls

Next, let’s take a look at just how bad triple leaf walls can perform relative to their double leaf counterparts.

These are tests TLF-95-107a (double leaf) and TLF-95-153a (triple leaf), taken from IR-811, a document published by the National Research Council of Canada. This data is copyright NRC Canada and shared with permission.

The difference here is stunning to say the least. It’s even more remarkable when you consider that the same type of construction, and same type and amount of materials were used in each case.

Double leaf – resilient sound clips and hat channel on joists, one big air space	Triple leaf – resilient sound clips and hat channel between drywall layers, small air space

The STC values shown above are from a series of tests run by Owens Corning in 1972 at Geiger and Hamme laboratories. While STC doesn’t tell the entire story, the point is clearly made.

Summary

Triple leaf (or quadruple or higher # of leaf) constructions should be avoided like the plague. You will always get a lower level of sound isolation, and this loss may be most severe where you need performance the most – low frequencies.

First Step: Build the Platform

Regardless of the sound isolation products you use, you will need to build a platform that is independent of the existing framing.  These platforms are typically built using 2″ x 4″  framing with 16″ on center spacing or 24″ on center spacing.  The less connection points that one material has with another the better the performance in sound isolation.  So 24″ on center is recommended, but when the platform is under 70 square feet then spacing really won’t make much of a difference at all.  The basic construction of the platform is shown in the gallery below.  Build a box frame using 2″ x 4″ studs and then connect studs 16″ oc or 24″ oc within the box.  Top this frame off with a minimum of one layer of 1/2″ or thicker sub-floor material.

Second Step: Add Something Beneath the Platform

Here’s where you have a few options:

Joist Isolators

Joist Isolator are U-shaped rubber pieces that friction fit on the bottom side of 2″ x wood products usually either 2″ x 4″ or 2″ x 6″ joists.  Using this product is cheap, simple, and depending on how much sound you need to isolate it may be effective enough to be the only sound isolation product you use if you want to keep the budget down for your floor.  A quick way to estimate the number of joist isolators needed is to take your total square footage and multiply by .65.  The smaller the area, the less likely that number will work so sometimes it is just better to draw the platform out and count how many you will need.  For small platforms you can space the joists 24″ on center, but for larger areas you will want to space the joists 16″ on center to help stabilize this floating floor design.  From there you will need one isolator on each end of the joist and then every 2′ in between.   As you can probably see if you have a platform that is only 6′ x 6′ then you will only need as few as 24 joist isolators to complete the job.  Joist isolators should be installed on hard surfaces so using this product over existing carpet will be pretty ineffective unless you were to first lay down a layer of sub-floor before setting up the joist isolator and platform system.

Rubber Underlayment

Recycled rubber underlayment is another option and typically the most common option because rubber underlayment can be applied in layers making it thicker than a regular joist isolator and because it is a more resilient product than joist isolators are.  The durometer (hardness level) of recycled rubber underlayment is almost half of what a standard joist isolator is.  Installation for this option is simple and is also pictured below.  Measure your total square footage to make sure you have enough QuietGround, cut the underlayment to size so it fits beneath the platform you create, and then lay it down on the floor before you place the platform.  The underlayment must cover the entire bottom side of the platform so that no part of the platform comes in direct contact with the floor.  Multiple layers of underlayment will improve performance and since the area you are covering is so small and underlayment typically only comes in 4′ x 25′ or 4′ x 30′ rolls we suggest using what you got.  : )

Other Options

You can add other products below this platform as well.  There are thick gym mat products, mass loaded vinyl (MLV), thick cork (6mm+),  and other ‘sound board’ type products that you can use.  We recommend the two options above over anything else because of the resiliency of rubber cannot be beat.  Dealing with deep vibrations you will need something resilient beneath the platform so the use of rubber is always recommended.  A thick gym mat can provide some decent results, but the mat will need to be over an inch thick which makes for a sometimes too cushy of an underlayment.

Third Step: Add Something On Top Of the Platform

To minimize costs you can avoid this third step.  This of course assuming you have chosen to use either joist isolators or rubber underlayment as discussed in the second step.  Like the bottom side, there are several options for the top side of this platform.  Here are a few that we recommend:

Rubber Underlayment

Rubber underlayment is superior at dealing with structure-borne noise so it is a great option for the underlayment that you install on top of the platform.  Like the bottom side, cut the underlayment to fit covering the entire top of the platform.  Multiple layers in this situation is always better than one layer so make sure to get enough!  Something thick like a 1/4″ rubber underlayment is always preferred to a 2mm or 3mm underlayment.  The rubber underlayment does not need to be attached to the top of the platform in any way.  To finish off the design you can lay a section of carpet over the platform and attach to the sides of the platform or just leave the underlayment as it is uncovered.

Mass Loaded Vinyl

A quality barrier will perform very well in this situation and since you are covering such a small area we recommend thickening up that barrier going with a 2 LB MLV over the more common 1 LB MLV.  The 2 LB MLV is as thick as one layer of QuietGround 250 rubber underlayment, but you do have the added weight with the 2 LB MLV which will help isolate more airborne noise than the QuietGround can.  The cost for the 2 LB MLV is a little more than QuietGround and if you layer the QuietGround then the 2 LB MLV will not perform better than the QuietGround.  But as a single layer underlayment, the 2 LB MLV is quite a performer!

Green Glue

The most popular sound isolation product online is without a doubt Green Glue.  To use Green Glue in this situation you will need a second layer of sub-floor screwed to the existing layer on top of the platform with Green Glue applied at a rate of either 2 tubes per 4′ x 8′ sheet or 3 tubes per 4′ x 8′ sheet.  This system will add a decent amount of mass from the extra layer of sub-floor and also the most damping that any product can provide between the two layers of sub-floor.  Performance for this option should be very similar to the QuietGround and 2 LB MLV options discussed above and also be very competitive in overall price as well.  The only drawback is if you add a second, permanent layer of sub-floor to your platform then it will become pretty difficult to move the platform if you ever need to.  If your platform is going to stay put for as long as you have it then this is of course not a problem.

Case Study

We had a customer in Minneapolis that likes to drum on an electric drum set in his apartment.  The only noise he really generated was the sound of the drumstick against the drum pads.  This sound was transferring directly to the neighbor’s below and he was receiving complaints about this.  So he contacted us to find a solution and the pictures below were taken by him showing what he had done and the final results.  Here is a quote from him about what he did and his results:

The QuietGround is working great!  I built a 5′ x 4′ platform out of 2″x4″s and a 0.5″ plywood sheet on top.  Since I didn’t want any of the roll to go to waste, I put two layers of the QuietGround between my carpet and platform, three layers on top of the platform, and some stock carpet on top of everything.

I have been rocking out pretty hard for some time now, and I haven’t heard a word from my floor neighbor.  I even contacted her and asked her to call me if there were ever any problems with the noise.  Still nothing!   I could have probably used less than 5 layers of the QuietGround to do the job, but I haven’t had any complaints so I have no reason to change the setup.  Thanks for the suggestion for building the platform by the way, I think that was key to isolating the sound.

Conclusion

Isolating sound transfer in a small area can be very simple and cost effective.  It also makes for a fun weekend DIY project–if you are in to that sort of thing!  With a basic platform and some sound isolation products beneath the platform and/or on top of the platform you will notice some dramatic results with minimal cost.  It is always recommended to treat the entire room rather than just the direct area that the sound is transferring through, but quite a bit of sound will want to flank through your floors so a simple platform will still reduce a serious amount of sound.

[View with PicLens]

Can Joist Tape Isolate Sound?

Not really.  Best case scenario if you were to add the tape to a 2″ x 4″ wall with 1 layer of drywall on each side you will find an improvement of 1 STC point.  This rating is based on an unofficial test performed by someone capable of performing a legitimate test and not just speculation.

Here’s the story for the test mentioned above and a pretty good summary of the world of joist tape sales:

A customer interested in finding an effective and affordable way to isolate sound on his projects contacted a seemingly reputable online sound isolation product provider.  They told him if he added joist tape to one side of his wall and hung just one layer of drywall then he would find an improvement of 10 STC points.  So he followed their instructions and applied the strip, then hung the drywall, and then sealed all the angles and joints with their acoustic caulk.  He ran some tests on his newly isolated wall and received results that provided an increase of 1 STC point.  So he called up the supplier and asked them why it did not work as advertised.  They let him know he needed to add the joist tape to both sides of the wall to achieve the 10 STC point increase.  So he removed the drywall from the other side, added the tape, hung some new drywall, sealed the wall, and ran a test.  There was no increase in STC rating.  He called the supplier and was only able to reach their voice mail and did not receive a return call.  He decided to drop it and moved on to using resilient sound clips in his projects.

Why Does Joist Tape Not Work?

If the tape is intended as a damper then it will not be successful as the tape has no damping properties and the foam material used to make this tape is not considered a legitimate damping product.  If the tape is intended to decouple the drywall from the stud then it will also fail as the joist tape is immediately shorted once the drywall is screwed into the stud through the tape.  So in terms of damping and decoupling, the joist tape simply does not have the ability to perform as a sound isolation product.

Are There Similar Low Cost Alternatives To Joist Tape?

There are some other options that will provide more benefit than joist tape for minimal cost.  The most basic option is using a damping glue on your studs or joists before hanging the first layer of drywall.  The damping glue most commonly sold for this is Green Glue.  There are no sound tests to support the claim that Green Glue on the studs and joists will provide a significant increase in isolation, but this is a method commonly spec’d on commercial projects and the concept is simple/logical.

You may be wondering why Green Glue on the studs would be better than tape on the studs.  The reason for this is because Green Glue is considered one of the best damping products manufactured.  Green Glue will effectively reduces vibrations between the contact of the first layer of drywall and the stud/joists.  Green Glue in no way attempts to decouple the drywall from the stud so the fact that the screw passes through the glue to the stud will not affect performance.  In fact, it will improve the performance of the Green Glue because it will help the Green Glue compress between the stud and the drywall.

Conclusion

Applying any product between your stud or joist and the first layer of drywall will not isolate a significant amount of noise.  Using a product like joist tape or integrity gasket will not provide any increase at all.  If you want to squeeze out a couple extra STC points from your isolation efforts then applying Green Glue to the studs is a real affordable way to accomplish this.  In the end though, decoupling and damping the entire wall or ceiling rather than just the studs is always going to give you the best bang for your buck.

Does the QuietBox Work?

The QuietBox definitely does allow you to use recessed lighting in your ceiling without reducing the acoustic integrity of your ceiling.  The QuietBox is made of 3/4″ MDF which is a very thick and dense material that provides a significant amount of mass to improve isolation.  The product that really helps the QuietBox isolate sound is Green Glue.  The Green Glue is applied liberally at a rate that is the equivalent of 3 tubes per 4′ x 8′ sheet of material.

If you are using double layer drywall and Green Glue on your ceiling then the QuietBox will perform as well as your ceiling.  If you are installing sound clips on your ceiling then the inclusion of the RSIC-DC04 clips will help maintain a consistency in your theme of decoupling.  In terms of sound isolation, think of the QuietBox as an extension of your ceiling.  The level of performance the QuietBox provides will in no way negate the isolation performance of your ceiling.

How Do I Install A QuietBox?

Our QuietBox is attached directly to your joists using RSIC-DC04 clips.  These RSIC-DC04 clips are included with each box and very easy to attach to both the joist and the QuietBox.  The attachment of the QuietBox is very simple, but does require electrical work to bring power to the recessed light.  We can only provide installation help in regards to the box itself.  Please click the link below to review the steps to installing a QuietBox.

READ OUR IN-DEPTH QUIETBOX INSTALLATION GUIDE

QuietBox Product Specs

Recessed Lighting Specified For This Box

We chose the Halo line of lighting products because of the affordability and availability nationwide.  Halo products are available at almost every electrical wholesale supply house and every Home Depot or Lowe’s in the United States.

For 6″ Lighting: Halo 6″ H7ICT and Halo 6″ H7ICAT.

If you do not have the Halo 6″ light that we have specified then make sure your 6″ light fits the specifications of the light to the left.  The QuietBox allows for 8″ of height within the box.  Allow for 1/2″ of this 8″ to remain a gap between the back of the light and the interior layer of drywall.

For 5″ Lighting: Halo 5″ H5ICT and Halo 5″ H5ICAT

If you do not have the Halo 5″ light that we have specified then make sure your 5″ light fits the specifications of the light to the right.  The QuietBox allows for 8″ of height within the box.  Allow for 1/2″ of this 8″ to remain a gap between the back of the light and the interior layer of drywall.

For 4″ Lighting: Halo 4″ H99ICT

If you do not have the Halo 4″ light that we have specified then make sure your 4″ light fits the specifications of the light to the right.  The QuietBox allows for 8″ of height within the box.  Allow for 1/2″ of this 8″ to remain a gap between the back of the light and the interior layer of drywall.

Most often clips are used on the ceilings while the walls are built as a double stud wall or staggered stud wall.  Retrofitting for a double stud wall requires that you remove the existing drywall before building the second set of studs.  The second set of studs should be spaced at least 2″ from the existing wall framing.  Double that gap and you will raise performance by about 5 STC points, double the gap again and raise your results by another 5 or 6 STC points.  Resilient sound clips will perform as well as a staggered stud wall and the cost per square foot will definitely be less than staggered stud walls.  Read more about decoupling, Understanding Decoupling.

Damping with Green Glue
The most effective way to improve the damping for your project is to use a damping glue between two layers of drywall.  The most commonly purchased damping glue is without a doubt Green Glue.  Using a damping glue reduces the severity of resonance problems, and it reduces the ability of structures to conduct vibration.  Reducing vibrations will keep sound from traveling through your framing and to the rest of your house.  Using Green Glue is the same concept as products manufactured by QuietRock or Supress, but the formula in Green Glue is lab tested to be more effective in terms of sound isolation and more cost effective as well.  There are also other types of damping that are often used in sound isolation.  For instance, our pipe wrap which is used to dampen vibrations in drain pipes and also on anything made of sheet metal.  Pipe wrap is actually a very versatile product that provides basic constrained layer damping on any plastic or metal surface with basic peel and stick installation.  Read more about damping, Understanding Damping.

Increasing Mass with Extra Layers of Drywall or MLV
Adding more mass to the wall helps. To make a BIG improvement, you have to make a BIG change in mass. For example, to improve sound isolation by about 10dB you would have to quadruple the number of drywall layers on your wall – from one on each side, to 4 on each side. Mass makes a much larger improvement when combined with other techniques such as decoupling.  Products like our Mass Loaded Vinyl will be a much more effective solution for adding mass to your walls, ceilings, and floors compared to adding extra layers of drywall.  Each layer of 1 pound MLV (1/8″ thick) is estimated to be equal to the effectiveness of 4 layers of 5/8″ drywall in terms of sound isolation.

Absorption with Insulation
If there is no insulation in your walls, add some.  This will help only slightly if the drywall is not damped or not decoupled, but will still help.  The rule of thumb with insulation is to make sure and at least use some.  Think of an empty wall cavity as an empty drum, if you hit the drum sound will travel easily.  If you fill the drum with insulation, sound will still travel, but it will be muffled.  We recommend using standard fiberglass insulation that fits the wall cavity or ceiling cavity you are working with.  Additional improvements are seen from using R-19, or even thicker, but these improvements are progressively smaller, and generally don’t help with low frequencies.  Use something, but you can save yourself money by not spending exorbitantly on extremely thick insulation or exotic types of insulation.  Better yet, take the money you saved, and put it towards something else (like one of the other 3 areas of improvements).  In general, anything thicker than R-19 is into the realm of diminishing returns.

CONCLUSION

These four areas of improvement are interactive.  For example, adding mass to a decoupled wall is more effective then adding mass to a standard wall.  And using multiple layers of drywall (mass) with multiple layers of Green Glue will significantly increase performance of Green Glue’s damping abilities.  For the best results you should include all of the four principles in your sound isolation project.  View our site to learn more about Green Glue, Resilient Sound Clips, and other products you should consider for your project.

The RC Assurance Clip acts as an impenetrable washer that puts extra space between the channel and the joist.  The snap on clip works with any resilient channel but is specifically designed for use with RC Deluxe from Dietrich.  RC Assurance Clips are used with resilient channel to eliminate the possibility of short circuiting your resilient channel installation.

RC Assurance Clips will not improve the performance of a successfully installed resilient channel system, but will ensure that your resilient channel installation is a success.  Almost every resilient channel installation will have at least one short and most installations will typically have short circuits in 15% or more of the connections.  While decent results can be accomplished with resilient channel, if you have multiple short circuits then the benefit of the resilient channel will be completely negated.

Developed a number of decades ago, resilient channel is one of the first sound isolation products used.  The popularity of resilient channel has been reduced significantly with innovations such as resilient sound clips and Green Glue, but resilient channel remains pretty popular in some parts of the United States.  One of the reasons resilient channel has become less popular is a huge and common issue with the installation of resilient channel.

The typical design and UL assembly calls for a fastener of 1”.  The typical installation utilizes a 1.25” or 1.5” fastener, mostly to aid in the “grab” of the screw to the channel.  This minor modification assures that 15% of the connections or more will be compromised and that the performance of the system will short circuit the low frequency transmission effectiveness of the system.  Now that lab tested 52 becomes a field 42.  The resilient channel needs another 0.375” to assure that connections are limited between the gypsum board and the joist assembly.  The RC Assurance Clip provides that space.

How Many Would I Need?

Each stud or joist that your resilient channel crosses will require an RC Assurance Clip.  The number of clips you need will depend on the spacing of your studs or joists and the spacing of your resilient channel rows.  Framing is typically 16″ on center and resilient channel is typically spaced 24″ on center.

Use this table below to help decide the number of clips you need.  Choose your framing spacing off to the left and the spacing for the resilient channel from the top row.  Then take your total square footage of all the areas where resilient channel will be installed and multiply it by the corresponding number below.  That will be a pretty good estimate of how many clips you will need.

So if you are putting resilient channel on an 8′ tall wall that is 12′ wide then you will need approximately 50 RC Assurance Clips if you space your resilient channel 2′ on center from floor to ceiling.  A quick calculation for how many clips you need can be accomplished by taking the total square feet of your wall or ceiling where you are installing the resilient channel and divide by two.

How Do I Install These Clips?

• Resilient channels should be RC Deluxe as manufactured by Dietrich. Or equal dimensionally manufactured product.Nominal dimensions are:

  a. 2.5” overall width
  b. 0.50” thickness dimension
  c. 0.50” screw area for the RC Channel to the joist
  d. 1.50” screw area for gypsum board to RC Channel
  e. 25 gauge galvanized steel

• RC Assurance is a spacer that is used in every location where a resilient channel is connected to a joist.
• RC Assurance is designed to snap on to the 0.50” FLANGE of a resilient channel with the pinch point on the top and bottom. The 90 degree leg points down toward the open area of the resilient channel.
• Spacing for Resilient Channels varies from UL Assembly & may be between 12.0” on center to 24.0” on center. Please consult your project specifications for proper spacing.
• Layout all resilient channels, following the recommended guidelines of the Gypsum Contractors Association, UL & the project specifications.
• FASTENING THE RESILIENT CHANNEL TO THE JOIST WITH RC ASSURANCE™
  For installation with RC Deluxe from Dietrich, snap enough RC Assurance onto the flange of the resilient channel to fasten the entire 12 foot section, one for each joist connection; RC Assurance will lock & slide to the proper position. Use a 1 3/4” Type “S” bugle head screw to fasten the assembly to the joist. Complete the installation of the channel leaving a small (0.125”) gap between the structural wall elements & the butt end of the resilient channel. Where possible, utilize the screw holes in the resilient channel but where alignment with the center of a joist does not work screw through the resilient channel to fasten to the joist.
• SEAMING RESILIENT CHANNEL
  Most assemblies require a 4.0” overlap of resilient channel butt ends. For this application, slide the two flanges into the RC Assurance & screw through both pieces to fasten to the joist.
• CONNECTING GYPSUM BOARD TO RESILIENT CHANNEL
  Consult the UL Assembly specification or the project specification for the type of screw to install. Typically, Type “S” or Type “W” bugle head screws are required. RC ASSURANCE is typically installed with 1.25” Type ”S” screw for the first layer of gypsum board and with a 1 7/8” Type “S” screw for a second layer.

DOWNLOAD THIS INSTALLATION GUIDE AS A .PDF

Conclusion

You only have one shot at attempting to isolate sound.  If you decide to go with a resilient channel system and you short circuit the channel then your efforts will not be effective.  RC Assurance Clips are very affordable and only add a cost of about fifteen cents per square foot to your project.  The benefits of the RC Assurance Clips is huge compared to the minimal cost which is why this clip is a must if you are planning on installing resilient channel on your project.

Click here to purchase RC Assurance Clips from our store.

A typical exterior wall is made up of a layer of drywall, 2″ x 4″ framing, R-13 insulation, a layer of OSB sheathing, and either siding, stucco, or brick.  Exterior walls will also of course have windows and a door every now and then.  The STC rating of your exterior wall will not be much better than your interior walls.  An STC rating for a regular interior wall will be somewhere in the low to mid 30′s while your exterior walls are usually in the high 30′s to low 40′s.

The first thought by most customers is to purchase a ‘save-all’ sound isolation product to make all their troubles go away.  Whether you buy Green Glue, resilient sound clips, mass loaded vinyl, heavy exterior doors, ‘soundproof’ windows, specialty insulation, or whatever other product someone is willing to sell you; your efforts will not be successful if you don’t incorporate multiple methods to improve sound isolation.

Deal With Your Weakest Links First

Exterior doors typically perform decently because they are usually solid wood and sealed very well from the exterior elements.  So while the doors aren’t the best for isolating sound, they are not usually the weakest link.  Windows, on the other hand, can transmit sound almost as well as they transmit light.    The average STC rating of a window is in the high 20′s, about 1/2 the isolation properties of your exterior wall, ouch!

Replacing your windows with ‘soundproof’ windows may help performance, but you will have a major construction project to undertake.  You will need to essentially remove a 4″ or so perimeter around the window to remove the existing window and install a new window.  If the exterior of your house is rock, brick, or stucco then this can be a major project.  Avoid this headache and high cost by adding a second window on the inner part of your window frame.

Adding a second window will increase isolation in two ways: 1) by adding an air gap between the exterior window and the newly installed interior window and 2) by adding an extra path for sound to have to travel through.  Simply adding a second double pane window you will increase the STC rating between your two windows to the mid to high 40′s.  At that point your windows will perform better than your thick exterior walls!

There are several companies that sell windows that can be used for retrofitting on the interior side of your windows sill.  Run a Google search or humor the Microsoft guys and try their new Bing to find a company near you that sells retrofit windows.

Watch the video below to see the effect of adding a second window to your window installation.

Now, Let’s Improve the Rest of Those Walls of Yours

Your windows now have an STC rating of almost 50, yipee!  Now you need to continue on fixing your new weakest link, your walls…

As I mentioned before, your exterior wall STC rating is likely somewhere in the high 30′s to very low 40′s.  The most basic way to improve your walls at this point with minimal demolition would be to add a layer of 5/8″ drywall with Green Glue at a rate of 2 tubes per 32 square feet.  Adding the Green Glue is simple, the hardest part will be to hang, tape, and texture the drywall.  Adding the Green Glue and additional layer of drywall will bring your STC rating up to the low to mid 50′s and will improve low frequency isolation significantly.

Now your walls will perform just as well as your windows and without major investment into your project this is likely as good as it will get.  You can add decoupling to this scenario to increase isolation, but this will involve removing the wall’s current layer of drywall.

If you would like to go this far then you will need to remove the drywall to avoid a triple leaf effect and then add resilient sound clips with hat channel to your studs.  After removing the drywall, rather than using clips you can also build another 2″ x 4″ wall in front of the current exterior wall, insulate the newly framed wall, and then hang a layer of drywall on the new wall.  This will improve the performance of your walls quite a bit more than a layer of Green Glue ever could and even better than a resilient sound clip system could.  The problem with this though (other than having to sacrifice another 6″ or so of floorspace) is your wall will be big and beefy with a great STC rating, but your freshly installed second window will still be rating in the high 40′s.

If your double stud wall has a rating of around 70 STC and your windows are high 40′s STC, then your final STC value for your wall will be much closer to the window rating than the uber-high double stud wall rating.

Conclusion

If you want to keep exterior noise out of your sanctuary then start by improving your weakest links.  Improve your windows and make sure you have a quality exterior door that is well sealed.  If that does not satisfy your appetite for sound isolation then add a layer of drywall with Green Glue or a similar damping compound (ie, Decibel Drop, QuietGlue, QuietRock) in between.

Still have questions?  I guess we didn’t explain the topic well enough.  Let loose, ask us a question or two.