Wednesday, March 08, 2006

Soundproofing hardwood and tile floors

I have been getting a lot of requests of late to discuss soundproofing a wood or tile floor in an upper apartment or condo unit. The solutions are pretty simple if you're installing wall-to-wall carpeting, but things get a little more complicated when you're dealing with hardwoods, ceramic or vinyl flooring. To begin with, when a manufacturers STC (Sound Transmission Class) claims appear to be too high always read the fine print. Generally they mean that you can only reach this high STC value in conjunction with a myriad of other products that must to be added to your floor or ceiling assembly. For example, if you're looking at ¼"cork as a floor underlayment and the manufacturer claims that it will give you 55-57 STC, keep in mind that this value will only be attained with at least 3 inches of gypcrete (light weight concrete) poured overtop of the existing sub-floor and most likely the addition of a couple of layers of cement board (Hardy or Wonder board) will be needed as well. All of the STC values of these products are additive and so the manufacturer makes his claim hoping you Won't read the fine print. Even though these values are additive, there is always the law of diminishing returns to contend with, so you still may not reach your goals even though it says you do on paper. Many times the call out for a floor or ceiling assembly is such that ceiling below must be floated on sound clips and furring channels or resilient channels in order to obtain the 55-57 STC values that some manufacturers claim to get from their product. Basically, no soundproofing product on it's own will give you a 55-57 STC value. If you find one that does, please let me know and I'll get it on the website immediately. There are no magic formulas. What it boils down to is simply this, very few products on the market today can give you an STC value greater than 32 to 35 STC on their own, and thus these high STC claims are very misleading to say the least. I had a customer who told me that a 1/8" cork mat would give him an STC rating of 55- 57 when laid beneath carpet and pad. I smiled and had him show me the cut sheet (spec. sheet) for the cork. The sheet called for the addition of a poured gypcrete sub floor and numerous other items that I can't recall off hand, that were needed in order to meet the 55-57 STC. Needless to say, he was shocked. Its back to that old adage, if it sounds too good to be true, it is! That being said, the absolute best way to soundproof an upstairs unit from a lower one is by floating the ceiling in the lower unit using The Americlips and furring channel (hat channel). This method is described in detail if you click this link: There you will find an in-depth guide that gives you detailed information on the proper methods for floating a lower unit ceiling. Another floating method is the use of resilient channel. This is the most common method used by contractors who have done any type soundproofing in their careers. This method, though more economical than the Americlip System, is only about ½ as effective and is generally installed improperly even by the most competent of contractors. The difference in cost for the Americlips is well worth it to effectively soundproof a ceiling from impact or airborne noise from above. Now there are other materials that can be placed over the subfloor above that will help stop impact noise as well as block most airborne noise from below or above. We carry 2 products for this express purpose, one is called American Impact Pro, and the other is called American Impact. These products are specifically designed to be installed beneath hardwood or tile floors and work well under carpet and pad as well. Mass loaded vinyl on it's own is not really good for soundproofing floors, it needs to have a breathing space in order for it to resonate and work to it's optimal best. This can only be accomplished by adding a decoupler to the MLV and that can get costly. When dealing with a hardwood floor, you can also use a product called America's Best, which is a mass loaded vinyl that is bonded to a layer of ¼" closed cell foam mat. This material will provide a certain amount of floor resilience that's prevents much of the impact noise from traveling downward, however the only way this system will work properly is if the wood planks are at least 6' in length, it is also preferred that planks be interlocking on the sides. The America's Best is a resilient product and will allow the new hardwood floor to actually flex when walked on. This resilience adds to the footfall protection to the ceiling below. Long planked wood floors are the only hard surfaced floors that will work with America's Best vinyl. Other floors such as vinyl or ceramic tile or Pergo floor systems will not work with this product as these surfaces will have a tendency to separate or crack. Finally, if your association board has a call out for IIC (impact isolation coefficient) then you will need to call one the professionals here at Soundproofing America and they will discuss with you the procedures you'll need to follow in order to meet that particular IIC call out. Impact isolation is a whole other chapter in the Soundproofing Bible according to Dr. Bob and will have to wait until next time! Thanks for reading and if you have questions, please give us a call.

As Always, Dr. Bob

Call Toll free (877) 530-0139

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