acoustical sound underlay, hardwood flooring sound barrier
Noisy neighbors and hard surface flooring don't mix. 

You can, however, reduce noise transference by using 'sound absorbing underlay' for floating hardwood or laminate floors.

Here are some general points about sound-absorbing underlays that may help you with your purchase decision:

Make sure that the underlay you choose has been tested using ASTM International (formerly American Society for Testing and Materials) standards .  Ask for paperwork that substantiates the underlay manufacturer's claims of the product's sound absorbing qualities. The product should have been tested in accordance with ASTM E-492.

The test results should show a couple of things....

1. An IIC (impact insulation class) rating
This is the number used to rate the sound absorbing characteristics of the underlay when noise produced from a test impact is measured.  The higher the rating the better the product is at absorbing sound.  Most products on the market have an IIC of between 60 and 75.

2. An STC (sound transmission class) rating
This measures a building material's (in this case underlay) ability to absorb audible noise such as voices or TV sound.  Most products on the market have an STC in the high 60's.

I tell my customers that 90% of the noise problems in condos exist because of lifestyle.  If you have a noisy lifestyle, then your neighbors will hear you. There is not a sound absorbing underlay on the market that is going to stop clacks and bangs, or noise from loud TV's from transferring through walls or wood flooring to neighboring suites.  Yes, a high density foam underlay with a good IIC rating will reduce the noise transference but it will not eliminate it. 

With this in mind, strata councils or building managers put rules in place (by-laws) that require a high IIC rated underlay be used for any new wood or laminate floor installations.  By doing this, they can say they made a reasonable effort to keep noise transmissions to a minimum should there be a complaint.

In some cases, just to keep the peace between neighbors, by-laws go further and demand that for example, 60% of the new hardwood or laminate flooring be covered with area rugs.  If you've ever lived beneath noisy people who have hardwood flooring you will understand why.

My advice....keep it simple.

1. Check your building's by-laws regarding sound barrier and IIC / STC requirements for hard surface flooring before installing your new floor.  In this case, it's better to ask permission than beg forgiveness!

2. Set expectations - living creates noise!  If you have a couple of active kids, play the piano, wear shoes that clack on the floor as you walk around the apartment, walk with heavy foot falls, you drop things, you like your stereo or TV sound turned up louder than most - then you are going to be heard by your neighbors.

3. Use area rugs to help reduce noise.

4. Do not nail wood flooring to an acoustical underlay.  This allows for too much movement in the wood floor pieces and will likely lead to squeaks and gaps.  Also, nails or staples facilitate sound transference similar to that of a tuning fork.  If you are nailing the flooring to a wooden sub-floor and want to insulate against sound transmission, then you will need an altogether different kind of sound barrier system - it's time to consult an architect or experienced builder.

If you live in a wood frame building with no acoustical concrete topping between floors, a sound absorbing underlay with the highest IIC rating, will not prevent sound transference.  Most underlays achieve their IIC and STC ratings from testing over concrete sub-floors. Wood frame construction and plywood substrates are notoriously bad at muffling sound and none of the products that I know of on the market are going to change that.

Hi-rise concrete buildings are best for natural noise containment because concrete is a great sound barrier.  Most hi-rise construction consists of 6" to 8" of concrete sub-floor between you and your neighbors below.

With all this said, a few underlay recommendations that are readily available and that I consider to be good value sound barriers for a floating floor installation are:

1. Dura-son
2. Sound Blocker
3. Floor muffler
4. Cork

There are many more on the market to choose from.  Check that the IIC and the STC ratings comply with your bylaws, and make sure that the IIC rating given to the product was gained using ASTM E-492.



10/24/2012 09:11:28 pm

I was just searching for relevant on this topic and came across your blog post.You provided me with very useful information. Thank you so much!

Reply
Chris
10/25/2012 10:33:05 am

That's great! I'm glad you found the post useful.

Reply
Chris Maskell
11/25/2012 05:19:15 am

Hi John, thanks for your question. I hope this helps....

Unfortunately I don’t know of an underlay that has an IIC rating based on a test done over a substrate system that is made up of 1 ½” of Gypcrete and 2 x 10 joists. Even though this is a normal substrate and very common in the market place. The problem is that if the underlay companies were to test for acoustical performance over this type of substrate the IIC and or STC numbers would be very low, this would not encourage product sales.

IIC’s and STC’s are measurements of sound transmission given to products that have been tested, usually to ASTM standards, in certain test settings. These test settings, to my knowledge, all involve concrete slabs of 6” or more and in some cases with a drop ceiling. With test settings like this high ratings are achieved which increases consumer confidence and ultimately helps product sales.
So when you buy a product such as DuraSon or Sound Muffler it is very important for you, the consumer, to look into the ASTM testing conditions that where used to attain the products IIC and or STC rating.


With this said the bottom line for you is your carpeted floor will be way quieter to live on for both you and your neighbors below, even with a DuraSon underlay beneath the laminate.
If you do go ahead, DuraSon would be a good option but you will not be experiencing the 63 IIC they claim because of the type of subfloor construction that you have.

So once again it boils down to a noisy or quiet lifestyle making the difference here.

Note that you can use area rugs to help muffle noise.

I hope this helps, good luck.

Reply
John
12/2/2012 09:38:11 am

Hi Chris,

Thank you for an honest no bull answer. I was hoping that I would not have to resort to carpeting again. I suppose only an acoustician can properly measure and rate a new flooring system over the existing structural design.

John

Reply
John
12/2/2012 09:38:31 am

Hi Chris,

Thank you for an honest no bull answer. I was hoping that I would not have to resort to carpeting again. I suppose only an acoustician can properly measure and rate a new flooring system over the existing structural design.

John

Reply
John
12/2/2012 09:39:09 am

Hi Chris,

Thank you for an honest no bull answer. I was hoping that I would not have to resort to carpeting again. I suppose only an acoustician can properly measure and rate a new flooring system over the existing structural design.

John

Reply
John
12/2/2012 09:39:52 am

Hi Chris,

Thank you for an honest no bull answer. I was hoping that I would not have to resort to carpeting again. I suppose only an acoustician can properly measure and rate a new flooring system over the existing structural design.

John

Reply
Chris
12/3/2012 01:01:28 am

Yes, an engineering firm would offer the test but it would be expensive and probably just confirm that even a good acoustical underlay is ineffective in this setting.
Good luck with your choice.

Reply
8/15/2013 03:46:57 pm

I am impressed with the blog writer. The author really needs an appreciation. Amazing work. Keep it up.

Reply
8/17/2013 05:35:06 pm

I visit your blog some day ago i feel really nice you have a great knowledge about sound absorbing. please keep posting. Thank you.

Reply
6/7/2015 05:09:02 pm

An informative article on sound reduction. The article is very lucid in structure and gives adequate information for easy understanding. Thank you for posting this.

Reply
Lise
4/14/2016 08:54:42 am

Hi Chris,

Our strata requires a FIIC rating of 65....how does this equate or translate to an IIC rating? I've been told by strata that the two are not the same or interchangeable. Thanks! Lise

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