My daughter's bedroom is right above the master bedroom. My daughter is a nightowl and we can hear her talking on her cell phone or walking in her room above. We are about to put new carpet in her room. My question is, can we have foam sprayed through the wood subfloor to dampen the noise. I don't believe there is any insulation in her floor now. Can holes be drilled in the floor to apply the foam or must the plywood floor be removed first?

Probably the best single thing you can do is not to insulate, but to remove the ceiling in your bedroom and replace it using resilient channels to attach the new gypsum board. These will reduce the sound transmission through the joists to your ceiling and therefore to your space. All the insulation in the world would not address that issue. Having installed the resilient channels, insulation would then help reduce the sound transmission of the assembly somewhat, and you can then install sound-absorbing insulation which is specially manufactured for the purpose, while your ceiling is removed. The carpet in the room above will also help to a degree. So would using 5/8 inch gypsum board on your ceiling instead of the probable existing 1/2 inch thickness.

Filling the cavities with foam would be very expensive and would not address the primary means by which sound is transmitted from the room above to the room below.

Richard, thank you for your reply. I doubt I could talk my wife into ribbing the ceiling down. I guess I will have to live with the noise.

Well, she wouldn't have to do it...

Blowing in insulation will help with sound control. It won't stop it completly(someone walking around) but I would bet it would definetly help with overhearing conversations above.

Actually in instances like this, we've used cork. You can get it on a roll and it's less than a 1/4" thick. Just roll it on the floor before installing new carpet. Very cheap and you will definitely notice a difference in the noise.

Dense packed cellulose (ground newspapers) insulation is better than fiberglass or foam. Both fiberglass and foam are mainly air and don't do much to slow down noise. Using the channels Richard talked about will help, but you don't need to remove the existing ceiling. Install the channels perpendicular to the joists and install another layer of sheet rock.

Only then, you can't insulate also.

There are special high-density insulations made for sound control...I wasn't talking about standard fiberglass roll insulation. They are called "sound-absorbing insulation", made expressly for the purpose.

Thank you for your reply. I would like to avoid doing anything in the master bedroom below. Have you heard of "Supress Sound-Engineered Products"? http://www.supressproducts.com/products/index.htm?gclid...XKwIsCFRT2YAod7nvuTA

Notice that in every single floor assembly illustration on their website, resilient channels are shown attaching the gypsum board ceiling to the structure, although they are not called out. As I said, they are by FAR the biggest single thing you can do to reduce sound transmission from above. It is a matter of resilient channels 60 to 70 percent, all other measures 5 percent each...something on that order. Whatever else you do, without the resilient channels, you WILL hear sounds from above. Basic physics.

I guess I'm not sure what resilent channels look like. Could you give me a description of what it looks like and how it is installed? If I torn up the plywood flooring to my daughters room, would I need to put resilent channels in all the floors on the second story? Would doing it only in one room make that floor higher than the rest of the second story?

The channels are applied on the ceiling side, lowering the ceiling not raising the floor. You will probably need to go to a commercial drywall supplier to get the channels they aren't a common item at Big Blue or Orange. They are shaped kind of like those posts they use for installing traffic signs a U with wide flanges to allow you to attach it to the ceiling.

The dense pack cellulose can be blown into the cavity without removing the sheetrock. All you need to do is cut a few access holes in each bay.

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Notice that in every single floor assembly illustration on their website, resilient channels are shown attaching the gypsum board ceiling to the structure, although they are not called out.

Richard, I think I see what you're talking about in the diagram. The resilient channels look like alumumun separating the gypsum board from the ceiling (which in my case would be the master bedroom.) I was hoping to avoid doing anything to the master bedroom. I guess that would be the best option.

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They are shaped kind of like those posts they use for installing traffic signs a U with wide flanges to allow you to attach it to the ceiling.

Ok, now I understand. Yes, it would be a bigger job than I would want to take on.

<<The dense pack cellulose can be blown into the cavity without removing the sheetrock. All you need to do is cut a few access holes in each bay.>>

I think this is my best option. So, you would recommend blowing the cellulose in the walls and the flooring?

Well, as I've said, insulation will get you a few percent of sound reduction, and the flooring a few more, and carpet and maybe cork above the flooring a few more, so the sound reduction might only end up being nearly twenty percent, because the joists will still transmit the sound directly to your bedroom ceiling. If you do all those things, don't expect miracles.

If you installed the resilient channels (which in effect allow the ceiling to "float" under the joists), you would achieve maybe 60% sound reduction by that step alone. Then you could also insulate, and replace your ceiling with 5/8-inch gypsum board, plus install the plywood, cork and carpet above. Then your sound reduction will be probably somewhat over 80% or more.

Rather than replace the ceiling with 5/8" rock adding a second layer would achieve additional noise reduction, with the channel even more. I wouldn't tear out a perfectly good ceiling creating a huge mess and disposal problem when I could leave it in place and add a layer for more sound reduction. Adding a 1/2" to the current 1/2" would give you 3/8" more than the 5/8" Richard is recommending. Getting it off of the floor joists and on to the channel would reduce the sound transmission more than just applying it over the existing sheetrock.j

you may want to check this web site out. I have had some work done in a recording studio with this stuff and it works great.

http://www.quietsolution.com/index.html