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Sound Transmission and Flooring Types

Home Improvement Info The Basics

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 dampening properties to reduce sound transmission.

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.

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Sound Transmission Ratings

There are three different standards for rating sound transmission. Each defines a different way in which sound is transmitted. The first two measure flooring sound transmission. 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.

   

Surfaces and areas under the floor influence impact isolation class. Underlayment and insulation significantly enhance the IIC. The “loudest” floor is stone or tile laid directly over concrete. However, the IIC scale does not account for joist noises like squeaking or rattling.

NRC (noise reduction coefficient) measures the amount of noise absorbed by the material and not reflected. A room with a high NRC rating eliminates background noise and echoes to help clarify speech. Theaters, for example, are constructed with a high NRC rating in mind. 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

The top layer of flooring is only the tip of the iceberg for flooring sound transmission. 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. When applied around the edges of the floor, flexible sealant is designed to fill gaps. For example, where the floor meets the wall, around doors or air ducts, blocking 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. Carpet and the padding under the carpet absorbs and deflects sound waves. Sound absorption is further enhanced with a thicker pad. Carpet is usually the cheapest option in the short run. However, it is 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. Cork creates a blissful peace that everyone will appreciate, including downstairs neighbors. It 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, the cellular structure of the cork breaks up the sound waves.

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

Foam-backed quality vinyl flooring has a cushioned, flexible surface, making 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 is a reasonably good choice for sound reduction with the addition of a quality underlayment. Underlayment adds a feeling of solidity and comfort to the floor. It reduces the hollow percussive sound produced by footfalls when laminate flooring is floated over a subfloor without 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.

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(112) Comments

  1. Heidi

    Hi, these comments have been very helpful, thank you.

    We wish to install a vinyl plank flooring, but need to comply with the ICC and STC rules of the condo.

    The manufacturer provides the ICC number is the product specifications, but not the STC measurement. How do I determine what the STC is for a particular product?

  2. Shannon

    I am managing the remodel of our church fellowship hall. We are doing a wet space in the walkways and by the food line (est 450sq ft) and carpet tiles in the rest of the room (est 850 ft). We have had porcelain tiles donated for the hard space however some want us to use Armstrong VCT ($.89 from HomeDepot). The ceiling has acoustic texture and we have 4 Windows with curtains and a light muslin swag over the fluorescent lights. Our concern is the acoustics. Will the Vct make a significant acoustic impact over the porcelain given the other acoustic measures we have taken?
    Thank you!

    • BuildDirect Product Expert Team

      Hi Shannon,

      Thank you for your inquiry! The VCT will make a difference in regards to sound. I can’t give an exact measure because I’m not sure of the rest of the room but there will be a difference in sound if you use VCT over the tile. Please let us know if you have any other questions!

  3. Marilyn

    My condo requires a fiic of 62. I want to apply 4mm cork tiles over the existing marble tiles in the entryway (taking up the flooring would be too loud for the neighbors) and once the grout lines are filled it should be a smooth surface. My question is, “what is the fiic of 4mm cork tiles?” Thank you for your response.

  4. Lisa

    I am on the Board of a condo association and we are trying to allow someone to put down laminate floors where previously only carpet was allowed. Can we ask for specific ICC or STC numbers be followed? Are those numbers industry wide that the proposed project can be presented to the board before installation?
    We don’t want to be the ones who say if the neighbor complains you have to tear it out. Looks like we should ask for 70 to 80 like you would get off carpet. Is that attainable with something under a wood or laminate floor?

    • BuildDirect Product Expert Team

      Hi Lisa,

      Thank you for your inquiry! It is common for apartment buildings to ask for a certain STC and IIC number to be followed. Usually it is around 72, I don’t think there is an underlay that would offer anything up to 80. The tenant would just need to find an underlay that offers the right level of sound dampening. Please let us know if you have any other questions!

  5. Bill Macdonald

    We want to put vynil plank or tile in a high-rise condo. We have to have noise reduction of 65 or better. Due to me being in a power wheelchair, we are told that will crush the plank or tile when it is over a sound barrier layer. Are there vynil tiles or planks that are themselves rated at 65 or better, without the additional layer? What are they?

    • BuildDirect Product Expert Team

      Hello Bill,

      Thank you for your questions. I don’t believe we have a vinyl flooring that has an STC or IIC rating greater than 65 for the flooring itself however there are cork flooring underlays that should handle the weight of the wheelchair as well as give you noise reduction quality that you need.

  6. Joanne

    The condo where we are installing a laminate floor requires a 76 IIC rating for underlayment (not cork). The highest I can find is 72 IIC. If we double this up, will we get double the IIC?

    • BuildDirect Product Expert Team

      Hi Joanne,

      Thanks for your question. Unfortunately Cork may be the option you need to go with to get the IIC rating that you are looking for as it is not a good idea to double up on two underlays. That could cause too much cushion on your flooring and will affect the planks ability to lock together.

  7. Leslie helm

    I recently had laminate floors installed and people in the unit below me say they can hear my footsteps. Is it possible to pull up the floor and add more insulation without making a mess of the floor?

    • BuildDirect Product Expert Team

      Hi Leslie,

      Thank you for getting in touch! I can’t 100% guarantee, but unfortunately you probably won’t be able to pull the floor up and reinstall it again afterwards. Most of the time pulling up laminate will damage the locking mechanism on the planks. I suggest getting in touch with who you purchased the laminate flooring from to check on whether this is a possibility, they could have more information on whether this will work with their product. Please let us know if there is anything else we can help out with!

  8. Ally

    I live in a condo that was built in 2009. It’s a beautiful building but the hallways (outside courtyard style hallways) to the upstairs units have begun to break down. (Cracks, uneven, and dirty). Whatever the surface is, It doesn’t feel like concrete, feels light, sounds hollow. (You can hear when everyone walks to and from each unit). I thought it could be power-washed, but was told we aren’t supposed to use water hoses upstairs – – yet the sweep and mop method only leaves it dirtier. I was wondering if you might know what surface this could possibly be? Also, the hallways were originally painted. Over time, the surface beneath is cracked and uneven. Simply painting on top of the problem won’t fix it. Can these hallways be resurfaced? If it’s not concrete, can it be fixed with concrete? Is this a common problem? What do you suggest?

    • BuildDirect Product Expert Team

      Hi Ally,

      Thank you for getting in touch! Unfortunately, without actually seeing the surface I can’t comment on what it could be or what the best course of action would be to address the issues. I highly suggest getting a contractor or flooring specialist out to take a look and offer some advice. They would have a much better idea on what it could be and what could fix it. Sorry we couldn’t be of more help! Please let us know if you have any other questions!

    • BuildDirect Product Expert Team

      Hi Daryl,

      Thank you for getting in touch! I wouldn’t suggest going with laminate because it can get moisture damage. You may want to look into luxury vinyl plank flooring options. They are becoming more and more popular, even more than laminate lately and are extremely durable. They are also water resistant which helps with the issues you would be having, this makes vinyl plank flooring really easy to clean as well. I’ve included a link to all our luxury vinyl plank flooring options:

      http://www.builddirect.com/Luxury-Vinyl-Tile-Results.aspx

      Please let us know if you have any questions!

  10. Pingback: Effective Noise Reduction in Learning Spaces | Students First

  11. Lori Nichols

    For the squeaky floor problem:
    My husband took out the nails in the row where the squeak was and ran a thin vibrating saw blade along the space between the two boards where the squeak was. He put back some nails. No more squeak! Another guy went under his crawl space and put a board on top of a jack and jacked up the spot above. I am glad we didn’t have to do that.

    • BuildDirect Product Expert Team

      Hi Lori,

      So glad to hear you were able to get the squeak fixed! Please let us know if there is anything else we can help out with!

  12. Phyllis

    Be careful with adding an additional underlayment. You mention the flooring has an attached underlayment. I was told by Home Depot that you can damage the floor by adding additonal underlayments as it doesn’t lay properly when it already has one attached. I used engineered hardwood and added a high sound resistant padding from Wisteria Lane. I have a very grumpy lady below me who complains about everything and I have not had a complaint (knock on wood) but I also use area rugs, not large ones but runners and place small rugs here and there. I also have a 55 lb dog and a 11 year old granddaughter.

  13. Ellen Sander

    We are considering a vinyl product for flooring a 3rd floor condo. It is called Coretec Plus and has a cork backing with IIC 62db and STC 62db. Because the flooring that has been used in other condos in the condo complex includes carpet, tile and manufactured wood, the HOA requires an underlayment – but are not specific re the ICC or STC. They say, “if the neighbor below complains, you may be ask to remove the flooring.”
    The manufacturer says a 1/4″ cork underlayment can be used with Coretec Plus but is usually not needed and is certainly not required by manufacturer. Do you feel we need to spend an additional $1000 for cork underlayment? What we want to use is new to the complex but there is cork under vinyl, it is simply attached. Thanks for your response.

  14. Rick

    I am installing 5 MM vinyl plank flooring on an above grade concrete slab. The salesmen recommend Tranquility acoustical underlayment that is also a vapor barrier. An old-timer told me to use roof felt as an underlayment. I was considering laying the felt down and the factory underlayment over that, in order to provide extra sound and insulation capabilities. What is your recommendation?

  15. alan smith

    Has any one won a battle with condo associations that will only allow carpet on the upper floors? If so, is there any IIC data you can provide? I want to use an sound reducing underlayment with a plank or cork floating floor. thanks, alan

    Read more: //learn.builddirect.com/flooring-info/noise/sound-transmission/#ixzz3Gmol9u9F

  17. Mari Etem

    I need to replace carpet on the second floor which makes noise when someone walks on it.
    I do not want to have carpet again. I would like to remove the noise and trying to cover the second floor
    to be clean and no noise. What do you suggest?

  18. Margo W / David S

    Recently my son purchased 1400 feet of engineered hardwood. After laying a hallway and bedroom, we have quite a bit of squeaking noise. Before finishing the other 900 feet, what can be done to keep to help quiet this irritating noise? The natural acacia wood looks great, but the sound is not at all acceptable. Besides returning the product, is there a secret to silence the wood?

  19. Ricky

    I am considering a wood laminate floor with insulation already attached to be instaledl in a condo high rise that requires 50 fiic. Is a per attached insulation adequate?

  20. donna steele

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

  21. Anne

    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.

  22. Phyllis

    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″.

  23. sheree williams

    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!!!!!!

  25. Darrell

    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 ?

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