Floor Treatment

Hello friends, In finalizing my attic studio plans, I'm a bit concerned about sound leakage through the floor itself. I am unable to treat the floor from below. It's hard to tell how much sound transmits through the floor and how much is going out the sides and roof, since I haven't yet built the interior acoustically-treated walls. I own the apartment below the attic, so I'm not concerned about disturbing myself. However, I am slightly concerned about how much sound might reach the apartment below mine from the attic above. I played music through an amp at live-band volume up there and while it wasn't oppressive, you could hear the lower frequencies in the apartment below mine. It'd be nice to have just a bit more isolation, though, again, I'm not sure how much was coming out through the roof and down the exterior walls of the building. The floor is currently very old tongue-in-groove hard wood. It's far from air tight. I was wondering how much some kind of self-leveling gypsum concrete might help with cutting sound transmission. Any advice? House is framed in oak and solidly built. I'd get a structural engineer to verify it, but I'm sure the floor could handle a good deal of weight. If I do use gypsum concrete to seal and level the floor, should I do that before or after I construct the walls? Thanks in advance for your thoughts on this. -- Nick

After further research, I'm now leaning toward simply applying two layers of subflooring (plywood) with layers of green glue.

I'm not totally sure what you mean. If you intend to make music noise at live levels in whatever coupled building blocks, I just think this cannot happen. You say the sound isn't disturbing, but.... Come with a detailed drawing and a precise description of the building technical stuff. And I might be able to give some founded advice.

I too am not certain what you want to accomplish ... but would like to mention that one of the esteemed designers here had posted a model for decoupling a drum kit via a 'floating' platform. Maybe something to consider as we learn more about what you are doing.

Oh sorry. Here are some details from previous posts. House is 112 years old and built solidly -- framed in oak. My apartment is between this studio space and the apartment below. So that's additional insulation from the sound. The drums will be V-Drums. Drummer will generally use head phones. The only live part of the drums will be hi-hat and ride (maybe the snare, though rarely) . I was planning to put the V-Drums on some kind of thick rubber matting such as the type used under weight-lifting apparatus in gyms. In general we don't play very loudly, thanks to the use of the V-Drums. The typical TV set can go louder than we will ever play. We typically play at a volume where we can still talk to each other without mics and without screaming. Vocalist does not need a mic to be heard for example. Hope this gives you enough information. So far I've put all the planning into the walls and ceiling. Only now have I started thinking about the floor. I do believe some sound attenuation is in order. Salesman at Trademark Soundproofing believed two layers of plywood with two layers of greenglue would suffice for my needs. I initially thought adding a layer of soundboard would be needed, but he didn't think I would get much bang for the buck with that given my needs. I always like to check here with objective experts. I'm almost ready to start building I think. Thanks. --Nick

I was planning to put the V-Drums on some kind of thick rubber matting such as the type used under weight-lifting apparatus in gyms.

That probably wont work to well. It will only work if the rubber has the right properties to "float" the weight of the drum kit plus drummer. If the drum kit is too light or too heavy, then you won't get the effect you are hoping for. The problem here is mainly the impact noise, created by stomping on the kick and hi-hat pedals. Search the forum for "drum riser", and you should be able to find the examples that RJ was talking about.

I was wondering how much some kind of self-leveling gypsum concrete might help with cutting sound transmission. Any advice?

The advise would be: DON'T DO THAT! At least, don't do it until you check with a structural engineer to make sure your floor joists can take that large extra load, and that your local building code allows you to do that.

I'd get a structural engineer to verify it,

Absolutely yes! But even then, this might not be a good idea. Isolation is an "all or nothing" issue. Just isolating the floor won't stop sound from flanking around that through the walls.

Salesman at Trademark Soundproofing believed two layers of plywood with two layers of greenglue would suffice for my needs.

But what exactly are your needs? How much isolation do you need, in terms of decibels? Without knowing that, neither the salesman nor anyone else can tell you what you need to do to isolate. - Stuart -

Hi Stuart! Bottom line, I need to mitigate background street noise of just a bit over 50 db. STC of 50 to 55 would suit my needs. After more research, I'm now looking at QuietGround 500 Rubber Underlayment to put under laminate flooring. The walls I'm installing should give me 55+ STC. The floor is the question mark, but it looks like the QG rubber should do the job. --Nick

Bottom line, I need to mitigate background street noise of just a bit over 50 db. STC of 50 to 55 would suit my needs.

I'm not sure I understand: Are you saying that the ambient level outside your studio is around 50 dB, and you want to get that down to zero?

The walls I'm installing should give me 55+ STC.

What walls are you installing? Do you have a link to the manufacturer, or maybe you could describe how they are built? Also, I think I said this before, but isolation involves the entire room: It is pointless to install STC-55 walls if your floor is only STC-40 and your windows are STC-35. You would be wasting a lot of money like that. Besides, STC is pretty useless for rating studio walls. STC is fine for houses, offices and shops, but tells you nothing useful about a wall for a studio. STC does not consider any low frequencies at all, so it is no use for telling you about how well a wall isolates drums, bass guitars, keyboards and that kind of thing, where much of the energy is in the low end of the spectrum. You should be looking at TL, not STC.

The floor is the question mark, but it looks like the QG rubber should do the job.

I VERY much doubt that a layer of rubber is going to give you STC-55!!! :shock: :!: Sorry, but that just isn't believable. According to their own website: "Adds about 5 STC ... in wood or concrete assemblies. Ratings will vary depending on overall assembly." Even that is probably optimistic. I very much doubt that your current floor is giving you STC 50, so it is extremely unlikely that you will get to STC-55 for your floor with just that product. In fact, if you take a close look at IR-802, RR-169 and IR-766 you'll see that for rubber mat with laminate flooring most likely there will be no improvement at all below about 400 Hz, in the absolute best case, and there is a distinct possibility that you could even lose isolation in the region below 400 Hz. in the worst case. So you could end up making matters worse for low frequencies. That is hard data from independent laboratory testing. - Stuart -

Soundman2020 wrote:

Bottom line, I need to mitigate background street noise of just a bit over 50 db. STC of 50 to 55 would suit my needs.

I'm not sure I understand: Are you saying that the ambient level outside your studio is around 50 dB, and you want to get that down to zero?

The walls I'm installing should give me 55+ STC.

What walls are you installing? Do you have a link to the manufacturer, or maybe you could describe how they are built? Also, I think I said this before, but isolation involves the entire room: It is pointless to install STC-55 walls if your floor is only STC-40 and your windows are STC-35. You would be wasting a lot of money like that. Besides, STC is pretty useless for rating studio walls. STC is fine for houses, offices and shops, but tells you nothing useful about a wall for a studio. STC does not consider any low frequencies at all, so it is no use for telling you about how well a wall isolates drums, bass guitars, keyboards and that kind of thing, where much of the energy is in the low end of the spectrum. You should be looking at TL, not STC.

The floor is the question mark, but it looks like the QG rubber should do the job.

I VERY much doubt that a layer of rubber is going to give you STC-55!!! :shock: :!: Sorry, but that just isn't believable. According to their own website: "Adds about 5 STC ... in wood or concrete assemblies. Ratings will vary depending on overall assembly." Even that is probably optimistic. I very much doubt that your current floor is giving you STC 50, so it is extremely unlikely that you will get to STC-55 for your floor with just that product. In fact, if you take a close look at IR-802, RR-169 and IR-766 you'll see that for rubber mat with laminate flooring most likely there will be no improvement at all below about 400 Hz, in the absolute best case, and there is a distinct possibility that you could even lose isolation in the region below 400 Hz. in the worst case. So you could end up making matters worse for low frequencies. That is hard data from independent laboratory testing. - Stuart -

See design diagram for layout. Walls will be wood studs, Whisper Clips and 7/8 .25 gauge Hat Channel, fiberglass batts, and two layers of 5/8" drywall with Green Glue between. There's only one window (control room) and I intend to cover that with another window, perhaps from Soundproof windows. Doors will be heavy, solid core and sealed. There will be double doors between control room and studio. I may make the outer door extra heavy as described in Rod Gervais book or insulate exterior wall and windows. Not sure yet. Most of the 50 db street noise now is definitely coming in through the exposed, uninsulated roof. That will be covered with insulation, the double-dry wall, clips and green glue, same as the walls. It's very hard to say how much transmits through the floor. I do have my apartment below the studio and I live alone. So there's a whole dwelling down there to cut sound transmission as well. The floor is currently hard wood (see pics). According to the manufacturer of the rubber underlayment: "The QG 500's STC rating is anywhere from low 50's to low 60's depending on the type of sub-floor and type of finish floor." That claim is what got my attention. If this is wildly inaccurate, then I guess I'm still deciding what needs to be done. What do you think, Stuart? I value your suggestions. -- Nick

I spoke to a structural engineer today. Cost of evaluation would be $800 to $900. Ouch. But better safe than sorry I guess and it'll be good to know how much weight the floor can handle. Maybe self-leveling gypsum concrete is a good option. In any case, I'll find out what the structure can bear.