subfloor sound deadening

Old 02-08-13, 04:50 PM
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subfloor sound deadening


About to finally start my flooring project and the hopefully final question is regarding the subfloor:

Currently I have a mix of carpet and laminate in the home which was in there, when I bought it. I ripped out part of the carpet already and underneath is a, I believe thin, layer of concrete. The laminate only had a thin layer of cork in addition underneath. There is someone living at least in some areas underneath me and while my neighbors never complained, I want to put in best efforts to deaden the sound. I don't mind, if the floor is eventually half an inch heigher - but what are my options?

I heard that you should not use two soft underlayments because the floor will be too wobbly and the seams of the laminate will simply break. That is understood. But some floor manufacturers like Quick Step for example offer an additional particle board to even out the floor, which kind of is an additional layer.

I read that a cement board would work as a dampening material because of the additional mass. Or a heavy particle board/ply wood would work as well.

So my question is: Does it make sense to put in for example an additional layer of 1/4" cement board or 1/4" 440 sound board (if that is not too soft), then a regular underlayment (foam/cork), then the laminate/engineered wood floor?

And if not, are there any recommendations from the community how to best prepare the subfloor to achieve a proper sound isolation and what kind of underlayment to use?

Old 02-09-13, 04:16 AM
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If you are planning on putting down a hard floor, there isn't much you can do to stop the sound from migrating from floor to floor. It will increase as the floor gets harder (ie. carpet to wood). Uncoupling the flooring from the subflooring will help, and a cork underlayment may be in order. I would check with my flooring manufacturer to see what they recommend, as you will have warranty issues at hand for the flooring.

IMO, increasing your hard surfaces won't gain any sound deadening benefit. It will all be in your underlayment. You may also want to check into flooring with attached cushioning. A little more expensive, but so is separate underlayment, so it may "wash".

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