Sound Transmission

iStock 000003457318Small 300x184 Sound Transmission

When it comes to flooring, the more muffled the sound, the better, especially in a multi-story building, house, apartment, or condominium. Fortunately, there are several good flooring choices with effective sound dampening properties.

Sound is transmitted when hard objects, like hard-soled shoes, furniture, dropped objects, or even dog claws impact a hard surface, like tile or stone. Without anything to absorb it, sound waves can spread, multiply, and echo off the walls, amplifying even a small sound to a distracting crescendo with the right acoustics. Given a large room with high ceilings and hard polished floors, a simple walk across the lobby of an office building, for example, can become quite a distraction.

Sound Ratings

Sound transmission is rated using three different standards, each defining a different way in which sound is transmitted. Sound absorption of floor coverings may be measured on two of those scales. The third covers room-to-room transmission, more appropriate for walls.

IIC (impact insulation class) is measured in terms of sound impact, or how well sound vibrations travel through a floor to the room below.

IIC 50 has the least impact sound absorption quality. While this may be appropriate for ground floors, it would be unsatisfactory for most on a high floor without a great deal of insulation in the area between the floor and the ceiling below. Most stone and tile will fall into this category.

IIC 60 indicates a medium impact sound absorption quality and encompasses floorings such as wood, laminates, and some vinyls.

IIC 65 is a high level of impact sound transmission absorption and includes superior sound reduction materials like carpet and cork.

IIC is greatly influenced by the surfaces and areas under the floor and the IIC rating can be significantly enhanced by the addition of underlayment, insulation, or by floating the floor. The “loudest” floor is stone or tile laid directly over concrete. The IIC scale does not account for joist noises like squeaking or rattling.

NRC (noise reduction coefficient) measures the amount of noise that is absorbed by the material and not reflected. A room with a high NRC rating would eliminate background noise and echoes to help clarify speech. Theaters, for example, must be constructed to have a high NRC rating. Without it, sound waves would bounce off the walls and crash into each other, creating a cacophony of continuous sound, making individual words impossible to distinguish. Carpet, with an NRC rating of .40–.50 is the most efficient absorptive material. Vinyl, cork, and rubber have a fairly high NRC rating, with hardwood, bamboo, tile, and stone at the bottom of the scale for sound absorption.

Under the Floor

Sound transmission is affected by more than just the top layer of flooring. Other factors include the underlayment and subfloor, plus adhesives and sealants used during installation. If used on a higher floor in a multi-story structure, insulation between the floor of one room and the ceiling of the room below plays an important part in deadening sound. Any kind of insulation packed between the joists will not only help to trap and dissipate sound, it will block the loss of heat or air-conditioning, effectively lowering your utility bills.

Installation Materials

The use of flexible acoustic adhesives adds yet another layer of sound dampening properties to the floor. Applied around the edges of the floor, a flexible sealant is designed to fill gaps where the floor meets the wall or around doors or air ducts in order to block channels where sound can travel.

Flooring for Sound Reduction

Carpet

Number one on the on all counts is carpeting. By definition, carpet is the antithesis of hard, echoing surfaces. Sound waves are effectively absorbed and deflected by the carpet and by the padding under the carpet, and the level of sound absorption can be enhanced with a thicker pad. Carpet is usually the cheapest option in the short run, but also the most problematic in terms of durability, cleaning, and allergy aggravation because it tends to trap allergens and dust.

Cork

Cork is a great choice for sound reduction. It does more than merely dampen sound; it absorbs it, creating a blissful peace that everyone will appreciate, including downstairs neighbors. Cork is such an effective sound reduction material that it is used on walls to soundproof recording studios to produce clear soundtracks without background noise. The key is in the porous structure of the cork. Rather than bounce around, sound waves sink into the cellular structure of the cork and are broken up.

In addition to the obvious benefit of sound reduction, cork flooring adds natural warmth to rooms and a slightly springy give that makes it comfortable and easy to walk or stand on and may even save dropped objects from breaking on impact.

Vinyl

Quality vinyl flooring that is backed with foam and has a cushioned, flexible surface, makes it a good choice for a sound reduction, but as with everything else, you get what you pay for. While you can install any tile over an existing floor, the material of the floor will influence sound absorption qualities. Top quality vinyl will help nullify that factor and provide a nearly soundless surface that has spring and give for comfort.

Laminate

Laminate flooring can be a reasonably good choice for sound reduction with the addition of a quality underlayment. In addition to absorbing sound, a layer underlayment will add a feeling of solidity to the floor and reduce the hollow percussive sound that footfalls can produce when laminate flooring is floated over a subfloor without the benefit of underlayment. The underlayment pads a laminate floor much in the same way that a pad works under carpet, adding give for extra comfort and insulation for overall warmth.

Related posts:

  1. Laminate Flooring Underlayment

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{ 34 comments… read them below or add one }

tim July 14, 2011 at 2:10 am

does anyone know where i can find the standards for sound deading for 2nd floor condos?
the floor is concret 6″ slab. i live in delray beach fl. thanks

Jill August 6, 2011 at 4:09 pm

Is hardwood or engineered hardwood any better than laminate for sound reduction, when the same underlayment is used?

Rodney Noriega August 9, 2011 at 4:07 pm

Hi Jill,

When using the 3 in 1 SoundChoice Underlayment (http://www.builddirect.com/Flooring-Accessories/-3-in-1-SoundChoice-Acoustical-Underlayment/ProductDisplay_10119_p1_10074922.aspx), it will act as an accoustical barrier to eliminate the sound feedback for laminate and engineered wood flooring. This works well if you are floating the flooring for installation. When stepping on the floating floor, you would be able to hear the sound effect as you walk.

Is engineered hardwood better than laminate for sound reduction with the same underlayment used? It really depends on a few factors such as the thickness of the laminate flooring, the type of wood species for engineered hardwood, the number of core layers if engineered hardwood, etc. The best way to test it is take a piece of laminate with the accoustical underlay beneath the plank and drop a golf ball on it. Then do the same with engineered hardwood instead and observe the difference.

As solid hardwood is usually nailed down, it doesn’t need the Sound Choice underlayment. Imagine trying to nail down a 3 1/4″ hardwood flooring onto a fibre 3mm underlayment (it will squish it). Plus, most people aren’t too concerned with improving the sound of solid hardwood, since they are satisfied with the sound of natural hardwood as is.

Cheers,
Rodney

Jill August 9, 2011 at 10:22 pm

Thanks Rodney. My strata corporation is making me crazy, changing their minds constantly on what they will and won’t accept, so any additional information is very helpful.

Angela August 22, 2011 at 9:55 pm

Hi,

I would like to replace my laminate flooring to tiling in the bathroom. My strata corp needs confirmation that the minimum value for the STC and IIC is 63. Should this still be required if I am changing from laminate to tile? My contractor is saying no, and my strata corp is saying yes. I don’t know enough about this to go back to my strata to plead my case. I would be grateful for any help.

Rodney Noriega August 24, 2011 at 12:00 am

Hi Angela,

That’s a fair question as several of our customers had inquired about the STC and IIC value for sound, as their strata corp had advised them of a certain value. The whole objective behind strata requirements is so that units don’t provide unncessary noise that can disrupt other residents in the area. For laminate flooring, you can reduce the sound level with our Sound Choice Underlayment (http://www.builddirect.com/Flooring-Accessories/-3-in-1-SoundChoice-Acoustical-Underlayment/ProductDisplay_10119_p1_10074922.aspx), as this provides an acccoustical barrier to eliminate sound feedback. Even though it has an STC of 54 and IIC of 58, it is sufficient for your application.

Having said that, you mentioned that you are changing from laminate to tile. You can go with our Anti-Fracture Tile Underlayment UltraLayer (http://www.builddirect.com/Flooring-Accessories/-Ultralayer/ProductDisplay_10119_p1_10077655.aspx) with a Sound Insulation IIC rating of 60, or the FiberBacker with also a Field IIC rating of 60. Both are good enough to meet the sound requirements, and I am sure your contractor would agree. The difference between these two is the Ultralayer is an easier install (Peel and Stick) compared to the FiberBacker (Glue Down over mortar).

Hope that information helps.
Rodney

Chris Durbin January 20, 2012 at 7:09 pm

I am doing work in a high rise building with a 50 STC rating between levels. It has an 8″ concrete slab and we are planning on using a 1/4″ cork underlayment. My question is, do we need a 1/2″, or will the 1/4″ suffice?

R. T. Simmons April 19, 2012 at 9:07 pm

I need to reduce or eliminate TV and radio sound coming from my downstairs neighbor. I plan on installing new carpet soon. Would a layer of cork (under padding and carpet) reduce the noise coming from downstairs? If so, what thickness would you reccoment?

Suzanne June 13, 2012 at 4:39 pm

I have an odd question. I have birds. I have really LOUD conures. What I am trying to achieve is a sound-deadening removable covering for their cages. Basically, I should have a room for them where I can just shut the door. But I have a ranch (rambler) style home and there is a lot of open space. What I was thinking of doing was to create a cover with cork panels that could be removed during the day when the household is awake, but yet allow the birds to squawk early in the morning when they want to (and without disrupting the rest of the free world while doing so). I mean, obviously I could just give them away but I am trying to find a solution that would allow me to keep them.

Marlene B. Wallace-Tranowski July 4, 2012 at 1:21 pm

Any hopes of getting my questions re sub-flooring for sound reduction for wood laminate floors??
Please???

Linda July 21, 2012 at 2:17 am

I am renovating a condo on the 7th floor. We are installing porcelain tile over a, 8 ” concrete floor. All cracks in concrete are sealed. There is a metal grid below the concrete in the plenum to reflect heat. Below that is sound absorbing ceiling tile.
The neighbors below have not heard major grinding, pounding, or demo in our unit. The HOA insists that we install an additional sound barrier. Several engineers have told us this is not needed. This will add another $2,000.00 to an already very high renovation cost.
It seems to me that the tile, concrete, metal, 2 feet of air and suspended acoustical tile should be more than enough to prevent sound transmission.
Help! Please. Linda

Nancy July 29, 2012 at 1:21 pm

I am looking to replace engineered wood and vinyl flooring with travertine. I see the underlayment that you offer and I’m wondering if this is necessary? I’m not worried about sound problems, I’m more concerned with warmth and cracking. The main area is 12×27 plus a hall and mud room. With that long of a space, would this allow for protection from crackign or is it just an unnecessary step? If it is a good idea, how is it installed?

Bob October 19, 2012 at 10:07 pm

Do they perform impact transmission tests on all vinyl and laminate flooring?

Thanks,
Bob

adeniyi November 14, 2012 at 11:01 am

My church is using a tiled floor how can we help the sound get better

Cindy December 12, 2012 at 3:21 pm

Has any won a battle with condo associations that will only allow carpet on the 2nd/3rd floor? If so, is there any information you can provide? I wanted to use a quietcork underlayment with a plank floating floor and was rejected.

Thanks Cindy

Namaste December 23, 2012 at 4:19 am

My husband & I would love to replace our carpet in our 2nd level condo. We are open to cork or wood or any product that has a similar or better sound reducing rating to carpet, so that our homeowners association will approve us tearing up our carpet

Any suggestions?? We will need prof to send our our hoa

Thanks

Mr kenny mann January 8, 2013 at 3:33 pm

kenny mann a live sound engineer.i needed help on which is good for sound in a church rug,wooden rug,tiles.

Angie January 15, 2013 at 4:20 am

I live on the 1st floor of a three story condo structure, when I first moved in 15 years ago all was fairly quiet, now I hear loud creaking above as well as too much neighbor noise, (conversations, walking, etc). I believe my neighbor installed tile in the kitchen, dining area, and hallways. Does anyone know what can be done to lessen the noise

Andrew February 9, 2013 at 7:31 am

In my house, the complaints are usually from the UPSTAIRS roommates regarding noise DOWNSTAIRS. Is this unusual?
Anyway, we haven’t installed our hardwood floors yet (just subfloor right now,) and were curious about underlayment that would dampen sound. We are also concerned about the quality of the material, as we know that certain underlayments are made with chemicals that can off-gas, causing health problems. (I’ve heard that vinyl is one of these.) Can anyone recommend a safe, non-toxic, sound-dampening underlayment? Thanks

joanne February 21, 2013 at 8:26 pm

I have Satin Finish product- Multi Plank Plus in a Oak Mocha that is glued down and want to put it in my bedrooms, however I need minimum IIC underlay 65, what products do you suggest, as well as type of glue? I am going this route as have not been able to find anything that looks like the same color in floating floors.

Thanks,

Kathy jordan April 8, 2013 at 6:30 pm

“Can anyone tell me if there is significant difference in floating floor laminate with underpayment
Attached compared to hardwood floors?

barico June 3, 2013 at 9:31 am

I live under a flat with vinyl flooring. it has mide my life a miserable living hell. Every single footstep is transmitted to the concrete resulting is a massive boom. Please dont use this flooring if you have people beneath you.

caroline saltzman August 3, 2013 at 6:10 pm

Are there any laws pertaining to what type of insulation is supposed to be used between floors in a condominium for protection against fire and noise .

Bill October 24, 2013 at 1:01 am

The unit above mine in a condo complex has a very noisy floor even with the Mohawk silent guard. They do not have carpet floors, and the noise keeps me up. since this didn’t work what can you recommend?

Sherry October 29, 2013 at 2:34 pm

Is there anything I can do to alleviate impact noise from the condo next to me? We do not share joists but we share a common subfloor. They have three kids who run and jump constantly. We feel the vibration and hear the boom-boom-boom of their jumping.

Scott November 17, 2013 at 2:18 pm

I have ceramic flooring on a concrete slab. Looking to replace with porcelien or travertine. What is the NRC for each. Thanks.

Business in Asia Blog December 23, 2013 at 6:49 pm

Excellent items completely, you only acquired a fresh reader. What will you advocate about your release that you designed some days earlier? Virtually any favourable?

Wayne January 27, 2014 at 8:06 am

I was wondering if you could help? Does engineered floating with a 14mm gap wooden floors make more noise or less than tiles ( with no additional isolation)?
I ask as I believe the wood floors that are floating by 14mm would make less but I am being told tiles do

Darrell February 11, 2014 at 11:27 am

Im replacing the floor in the Bath w/ cork , I’ve been told that the only option I have is to apply the flooring with glue and not the floating floor, My thinking is if I seal the perimeter and put a good water resistant barrier/underlayment to keep the sub floor dry this should be sufficient ( I quit splashing in the tub some time ago) so water on the floor is minimal , is this feasible ?

marcus February 22, 2014 at 10:44 pm

Using a ground floor or up floor . Does it really matter.

sheree williams March 5, 2014 at 12:29 pm

l want to purchase rolls of 3/8 cork rolls. to put down under tile on my 5th floor condo .
I have been told all l need to do to lay it is to clean the concrete floor, put a bonding agent on the concrete allow to dry then unroll the cork apply underneath the cork to the floor with a thin layer of the same thin set I am using on top of the cork to set the tile. Is this the correct procedure???????do I install one row of cork and tile at a time. Instead of 2 or 3 rows of the cork. I’m concerned about the cork wanting to roll up at the ends!!!!!!

Phyllis March 11, 2014 at 10:02 pm

Will the addition of cork underlayment along with a 3 mm underlayment help with sound absorbtion? What thickness of cork underlayment is best? Going on concrete slab 6″.

Anne March 15, 2014 at 1:17 pm

We’re laying 3/4 soft mahogany solid wood over Elastalon layer over original 60s intact 8″ vinyl over concrete. Does the vinyl add to the ST number? Elastalon falls a little short of coop rules.

donna steele July 30, 2014 at 4:12 am

What is the best flooring and backing for a 2nd floor condo that won’t kill a small budget?

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