Who told you cork was good soundproofing?

Cork sound control products are quite common in the flooring industry. It comes in thicknesses from 2mm up to 1/2" thick. What kind of flooring will go over it?

It may not be the best product for walls since there are other solutions offered (special fastening systems, sound reducing wallboard). Do you intend it to go under the wall material or on top of it? There are volumes and volumes of information on the internet.

You are talking about 'black cork'. This is a building grade material (which would then be covered with a 'final' finish like drywall or clap board/siding of some sort) which can be found in thicknesses upwards of 4" (I've heard of thickness as high as 8"...millionaires use this level of product).

There are very, very, very few building companies in N. America who handle this product. It is HYPER expensive. Stunning. Amazing. Outstanding. Thunderously expensive.

As a subfloor product, I would look at 1/2" cork underlayment sandwiched between GLUED planks of plywood. Do NOT pierce the cork with nails. An install like this would be considered a 'double stick'. Again, nice and expensive; yet highly effective. The glue = $1/sf for each application...and you will need two applications. The cork = $2-$5/sf. Plywood = normal 3/4" subfloor grade plywood - not OSB.

As for walls...remember to stagger your framing to avoid vibration transmission via physical contact; double stuff the voids with Roxul Safe N Sound. You will get both HEAVY DUTY noise reduction as well as an excellent fire break.

You are welcome to work with black cork. You will need a specialty builder to import it/purchase it from specialty building suppliers...and then you will need special (read expensive) architectural drawings with specific directions how to utilize/install this very special product.

There are a few design firms in California who have routinely used this material. You might reach out to them (should only be 1/2 dozen firms in all of California who know about it/have used it) to see if they A. have the product and B. have any advice on how to use it.

Thank you all for the feedback and product recommendations. I don’t think I need to go as bold as the black cork in these walls. Do you think the typical cork underlay would be effective in these particular walls (maybe seal edges with the acoustical caulk and then stuff with insulation? Too late for the staggered framing and don’t want to lose any additional space; will keep in mind for any potential future projects though! Last question: we only planned for cork on second floor for sound reasons but I’ve heard there are benefits to cork on a slab foundation as well. We’re in Southern California so I’m not too worried about a “cold feel” with the slab but if there is another benefit to the feel underfoot and also functionally with moisture prevention or even ‘give’ for seismic activity then I’d like to consider first floor cork as well. Thanks for any addl feedback.

You are barking up the wrong tree if you are considering using cork for "soundproofing" walls. There are so many other, better strategies for walls and the ceiling/attic space above the wall framing.

You need to do some research in the archives here, as well as Googling "soundproofing wood frame walls".

Forget the cork!

Cork flooring underlayment is not meant to go 'vertical'. It requires structure above and below. In other words, it MUST BE sandwiched between two rigid products. In the wall, you have to have it in between layers of drywall. So you will have to double stick the drywall. In that situation, you might as well use 'Acoustic Drywall'.

At this point, you are too late to do things 'properly'. Stuff the walls with Roxul and put up drywall. If you want MORE acoustic insulation, then use Acoustic Drywall in those areas were you want more acoustic insulation.

And if it is too late to stagger the studs in the walls it is FAAAAAAR too late to incorporate cork INTO or UNDER the slab for seismic upgrading. That type of thing had to be specified when the house was in the DESIGN phase.

You are welcome to use cork on the walls. It will cost ++money and several layers of drywall to get it to work. And the labour to do that will triple. Or you could stuff the voids with Roxul and pay the regular labour costs for drywall. It will be roughly the same result as using 1/2" cork flooring underlayment on the walls.

At this point, it is too late to properly integrate a comprehensive acoustic build utilizing cork and it's properties.