Does adding 1/2” OSB over 5/8” timber planks in order to cover with new floating floor minimize sound to floor below?

  • Have you looked at any of the questions with the tags sound-proofing or sound-deadening? There are 280 questions that should give you a really good start on an answer to this question.
    – FreeMan
    Jul 15, 2023 at 11:47

2 Answers 2


There are multiple sources of noise and ways noise travels. For example, voices are easily absorbed by soft materials like carpet, and padding helps with loud walkers and pet nails. OSB and floating floor do none of that. So it may help extremely minimally with voices, and if the floor squeaks a lot currently, attaching a second layer properly could minimize that, but for other sources of noise it will do nothing. To decrease noise you need to install absorbent surfaces or decouple surfaces.


Noise mitigation is a difficult problem asking for easy but impossible solutions.

I can't overemphasize how difficult proper noise mitigation is and how much work and money is thrown at underperforming techniques that only lead to disappointment.

Underlayment & Boarding?

Often underlayment or an extra layer of boarding is proposed but they do nothing effective.

The underlayment helps prevent floor crackling noises or bounce contact of the flooring caused by deformations when weight is applied. When the marketing material describes it as "noise reduction", this is the noise that gets reduced, and everything else is left to the buyer's wishful imagination.

An extra layer of boarding helps distribute weight application, which may help a bit in some cases of deformation noise caused by foot drop. Also the extra weight of the board helps a tiny bit with foot drop thumping. Voice or pet nail (as mentioned in the other answer) will travel anyway.

This same stiffening is the reason why double sub-flooring is recommended if tiles are to be applied: to protect the tile and grouted seams from applied strain.

Don't expect much from easy answers

To properly reduce noise transfer to the room under the floor (if that is your objective), you will have to open the ceiling and apply layers of heavy drywall sheets, noise absorbant insulation in the ceiling cavities, and decoupling rails to reduce coupling to the ceiling.

To reduce noise generation in the room with the new flooring, use underpadding to reduce crackling, and apply area rugs and curtains. (I know this is not always a desired option)

Whether you are willing or needing to resolve it this way, I would not spend the money or labour on double boarding the subfloor.

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