Soundproofing between floors

8 years ago

Our teenage son's room will be above our bedroom.
What inexpensive methods are available to soften the sound between floors? (he likes to play music)
Builder sprays foam on the exterior walls. I was thinking of doing this to the floor above us. Maybe add some fiberglass insulation also.
Ideas..

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bry911

8 years ago

There are quite a few threads that talk about this. Insulation helps but not that much. You need mass and absorption (remember sound is vibration). Lots of people use serenity mat...In my home theater I used the same concept but different (cheaper and better) material.

Rubber mats which are glued down between subfloor attached to the joists and the underlayment. Something like this (blue layers are glue) it works really well. You get none of the home theater noise in the other floors.

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Comments (7)

treehuggergirl
8 years ago
last modified: 8 years ago
Make sure to approve the HVAC plan. In our old house, the return air ducts connected this same bedroom configuration and you could hear almost everything between the two rooms.
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So I am going to answer the question first and then explain the answer later. It would be very expensive to keep all the flooring the same height without adjusting the floor depth. Serenity mat in your entire house is not going to really do it, and the cost of full sound proofing the entire floor is quite high and unnecessary. Many of the solutions such as Serenity mat are largely made for retrofit applications. It is much cheaper and better to properly design your space than it is to buy stuff to put on it. Background: We are only concerned with limiting bass, highs will automatically limit as we limit bass. Bass waves do work. There are two ways to deaden bass travel. The first is to limit the work - this is what all absorption products do, any compressible material will work, you don't need to spend the money for serenity mat in fact a lot of people (myself included) use horse stall mats from Tractor supply as a cheap and easy alternative. The second way to limit bass travel is to increase the work required, simply add mass. The best solutions will use both. For the serenity mat to work well you really need layers that look like subfloor - green glue - serenity mat - green glue - 2 layers of 3/4 plywood glued together - flooring, also nails into the plywood shouldn't penetrate the mat. This creates a big mass over the mat and limits the absorption needed by the mat. However you are still going to have sound travel above the room and through the walls. Making sure you joists don't create sound travel channels and soundproofing the garage ceiling will be a lot cheaper than sound proofing the floor. You can get away with a Mooney wall type garage ceiling (with double drywall) and Mooney walls (with double drywall) in the garage and essentially eliminate the bass travel and spend a lot less than you would on the mat. To be fair attic and HVAC travel is going to be a lot more significant and likely than bass gain from a garage. I run two SVS PB 13 Ultras for Home theater and two Velodyne DD18+ for music. Occasionally I will throw them all on for a movie with a good soundtrack. I doubt your husband gets more bass than that. The only thing I use between our theater and the living room above it is 2 layers of drywall glued between the joists along with sound isolation clips with 2 layers of drywall hanging from them. With all 4 subs going you can barely feel it in the living room (during big explosions you can feel a very low deep vibration probably in the 20 - 30Hz range (which you are not going to get rid of.)) So back to your question. You are talking a lot of glue, serenity mat and plywood to get the floor the same height. It is just not worth it.
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The noise solution is usually applied from below (as in when the basement was finished). Usually this is the cheapest, easiest solution because you gain access to the floor joists very easily. With the basement ceiling open, you can STUFF the joist spaces with two layers of Roxall Safe N Sound (creates both a fire break and a noise break). If your noise issue still remains, you can then add decoupling products before you hang the ceiling. If done this way, the cost of renovation is kept quite low. If you have to do this from above, as in your case, the costs just went up. Securing the first layer of subfloor (the things attached to the joists) will be the first order of business. If this layer is old and dry and the product is starting to crumble (ie. the screws/nails are coming loose) then you may have to remove EVERYTHING to the joists anyway (pray to the gods of renovation that you do NOT have to do this). Assuming you can leave the subfloor in place, you can then use 1/2" cork in between the first layer of subfloor (the part screwed to the joists) and the second layer of underlayment (the nice plywood that will sit directly underneath your floor). You can glue the cork into place. Allow the adhesive to cure and then glue the second layer of underlayment down onto the cork. Do NOT pierce the cork with metal. Metal screws become a conduit for noise (aka. thousands of telephone wires). Once your 'cork sandwich' is in place, you can then start to rebuild your kitchen. Of course if you MUST get down to joists, then go ahead and STUFF the joist spacing with a double layer of Safe N Sound. It is relatively cheap and easy to use. Then lay your beautifully thick subfloor followed by another thick layer of plywood. Making sure everything is screwed into place. Remember: density/thickess/total mass kills noise.
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keywest230
8 years ago
Inexpensive methods that work: none.
bry911
8 years ago
There are many relatively inexpensive methods that work.

I run dual SVS PB13 ultras in my home theater I used the diagram of the floor above along with cheap fiberglass insulation a mooney wall type ceiling and two layers of drywall on the ceiling. The whole thing set me back $1,500 and you can't hear it in the bedroom above without putting your ear on the floor, more sound comes in the window than through the floor.

I doubt they need that much soundproofing.
bznbaker thanked bry911
User
8 years ago
last modified: 8 years ago
The cheapest method of reducing sound transfer (it will not be sound proof) after eliminating connecting leaks like utility and HVAC penetrations and put two layers of drywall on the ceiling, is to suspend the drywall ceiling on some kind of resilient system. The cheapest system is 1/2" deep resilient metal channels. I use this system on all ceilings below a habitable floor. Here is a link to resilient metal channels at Home Depot (the channel is shown upside down). Be careful to not screw the ceiling boards to the joists.

It also helps to use a rubber like resilient layer below the underlayment or finish wood flooring in the room above. Of course, wall to wall carpeting is also helpful not necessarily for music but the sound of foot traffic.

Filling the floor cavity with insulation absorbs some sound but more importantly it prevents sound from traveling horizontally from a crack above to a crack below. Any kind of insulation will have essentially the same effect but mineral wool would probably be the most cost effective if installed tight to the joists. Spray foam has the advantage of sealing cracks but I doubt it is more effective. If there are recessed lights in the ceiling the housings must be rated for insulation contact (IC) and the permitted lamp output may be reduced. Of course, recessed lights would be a ceiling penetration so you should avoid them altogether.
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bry911
8 years ago
What JDS said is certainly considered the industry standard. I am personally not a huge fan of resilient metal channel if there is a lot of bass. You can get a vibration of the channel again the drywall.

I used mooney walls instead of resilient channel with screwed and glued drywall.

Essentially I have 81 square inches attempting to vibrate 9,216 square inches of material without worrying about independent movement.
bznbaker thanked bry911
User
8 years ago
A teenager ages fast so he isn't going to be up there for very long nor is he likely to have state of-the-art equipment so there is no reason to design the ceiling like a recording studio. Resilient channels lower the ceiling by only 1/2" and are cheap enough that they can be used for all of the ceilings in a 2 story house.

Don't let him put the speakers on the floor and be happy he doesn't play the drums - that's what I had to live with. A quiet house is not all its cracked up to be.
bznbaker thanked User

Soundproofing between floors

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