Hello, I would like your opinions on the "perfect flooring material design". The room size is 12x17x10. The room is located on the second floor. I need the floor to be" sound proof", and still have great acoustics. I have working knowledge of sound transmission and isolation issues. The floor is striped down to the floor joist with hat track and 5/8 rock on the bottom. Looking foward to doing it right the first time. I have not seen any ideal floor design postings. Help! I'm spinning my wheels. Thanks, Tom

Read everything here: www.soundproofingcompany.com

That will get you on the right track. :)

I read a post (Just how crazy is this idea for ceiling sound reduction) 9.30.04. Mr. Ravanaas is a wealth of knowledge. I need to know if concrete is the right/best material to stop low frequency loss through the floor because, beneath that floor is my living room. My first concern is, how many inches would be sufficient to stop the low frequency? My 2nd concern is, how many inches of cork or rubber would be sufficient as a decoupling layer? My 3rd question is, is there a construction standard for sound proof flooring? I hope my questions are clearer then my first attempt. Thanks again, Tom

I am researching this subject for a personal project and this article is worth the time to read:

http://www.cdnarchitect.com/issues/ISarticle.asp?id=77538&story_id=142098145538&issue=01012003&PC=&RType=

Send a PM to Ted White and ask him to post in this thread (so we can all see the answer).

"perfect flooring material design" eh? ;)

Well, you need a concrete slab on the order of 6" thickness to get sufficient mass, truly floating over an airspace of at least 12" (haven't done the math recently, but it may be more like 24"+) and supported only by big metal springs or thick neoprene pucks. The fully loaded static compression should be such that the resonant frequency of the floor system is at least 2 octaves below the lowest audible. So for a 5 Hz resonance, you need the springs or pucks to statically compress by 1 cm.

That's the sad truth of it. :(

At Sound Proofing Company Inc., in Teds library he shows flooring options where this may be an option for some, however, I don't think this is aggresive enough to deal with my low frequency needs. From my knowledge concrete (dense mass) is the only option? School me other wise. Got to be a better way. Thanks, Tom

Okay pefect flooring was a little over the top. How about better than middle of the road floor design.

Mass is great, but will still conduct vibration. If you are isolating your needs to just airborne sound, your task will be easier.

The trick is to lower the resonance point of that floor as much as possible.

#1 decouple the ceiling below from the joists. If all you have is hat track and drywall, this is coupled. You would want clips + channel and double 5/8" rock

#2 install R19 fiberglass in the cavity

#3 Double 3/4" subfloor with Green Glue (or 3/4" + 7/16" + 7/16" amd two layers of Green Glue)

#4 Acoustik Mat (3/8") Can be ommited if carpet + pad is coming along.

#5 Finished floor

As Terry pointed out, this will reduce, but nothing will eliminate all sound. You will be cranking out frequencies down to 30Hz, maybe, and you can't build a floor system that will have a resonance point below that.

Also, you will have flanking through the walls that will enter the room below.

Ted, Are your suggestions based on standard construction that would have the same old flanking issues or is this just a great design ? Flanking............. A free standing 4-6" concrete floor w/walls and ceiling that are free from mechical ties (less 16 or so rubber mounts between floor and steel sub structure). Maybe 6" of free air space between walls open to a 2000 sq. ft. air pocket above ceiling. Would this curve the flanking problems ? If so , are your floor designs aggressive enough ? Tom

Terry, Truly floating over an air space of at least 12", would this air space have to be under the floor ? Is this just an air cushion , If this air space works on floors ,ceilings and walls could a common air space work ? Would this air space be based on surface area or cubic ft. of room ? Thank you ,Tom

Terry, Truly floating over an air space of at least 12", would this air space have to be under the floor ? Is this just an air cushion , If this air space works on floors ,ceilings and walls could a common air space work ? Would this air space be based on surface area or cubic ft. of room ? Thank you ,Tom
The idea of a true floating floor (or entire floating room) is that the floor/room is entirely supported by compressible elements such as springs. These elements compress, giving the entire system a natural resonant frequency which is low. This resonant frequency has a simple numerical relationship to the amount which each element is statically compressed by.

Once you get above around 1.6 of this frequency, vibration begins to get isolated from the structure, and vice-versa. The higher above the resonant frequency, the more isolation. Hence the 2 octave minimum.

The rub is that between the compressible elements there is entrapped air. This causes the resonant frequency to jump up much higher than predicted, because air is pretty stiff. The isolation is rendered much less effective. So you need to make this air layer very thick so it forms a very soft cushion that does not interfere with the element compression resonance. The springs or pucks would typically be supported on piers. This is pretty impractical for residential construction, but not so for some high-performance pro sound studios.

- Terry

Ted, Are your suggestions based on standard construction that would have the same old flanking issues or is this just a great design ? If so , are your floor designs aggressive enough ? Tom

Tom, you are seriously limited in the extremes you can pursue. As already outlined (see Terry's excellent posts #6 and #12), the key is to get the partition's resonance point as low as possible. This is (only) done by adding mass and air cavity volume, assuming you have already decoupled the leaves of the partition and have absorption (insulation) in the cavity.


You have a wood joist system that will only hold just so much weight. You can't look at 100 lbs per square foot of cement.




You can make the ceiling cavity as deep as practical for you, but that won't likely be much deeper than your current joist system.

Even if the floor were 100% soundproof (an impossibility considering the low frequencies you anticipate) you would still have sound travelling down via flanking pathways.

So this isn't a matter of lack of aggressiveness. It's a matter of pure practicality. If you want that level of isolation, you need a separate building.

If you want that level of isolation, you need a separate building.

Magnetically levitated in a vacuum...$3.4 billion in today's dollars. Cheap at twice the price. :D

................I've read blog after blog where HT DIYers settle for a less then adeqate floor system and spend thousands on equipment . I live in a resort town where tourist play car stereos at alarming levels w/ massive bass that rattle my teeth and I'm inside the house! With an ocean breeze we contend with boardwalk announcements ,and lets not forget that damn helicopter flight path right over the house. Yes I currently have wood floor joist , but a 15000# concrete ,pan deck ,I beam & column system isn't out of the question for me. I need to get as much input as possible. My thinking here is start with a great floor and move forward. Maybe I'm asking the wrong questions ? Any input ? Thanks Tom

My thinking here is start with a great floor and move forward. Maybe I'm asking the wrong questions ? Any input ? Thanks Tom
Maybe you are, Tom. When designing for sound isolation, one cannot just pick one component, like a floor, and start there. It's not at all like choosing the components in an audio system. You have to engineer the system as a whole.

For really high performance sound isolation, this is not an easy task. You could spend years learning all that you need to know. Not that I am saying that you necessarily shouldn't do that. But do not expect a suitable design to emerge from a single forum thread.

Regards,
Terry

Maybe I'm reaching a little bit (Ya Think?) I'll take a couple of photos and post them. Its a old house, however, it's not typical contruction (suprise). Maybe you could spot some problem areas before I build or, suggest a better way. Thanks for all your input....................... The porsha handles great. The ford will get me there. I definitively don't want a 3 wheeled VW.

......Hello ,I'm looking at stc values of different wall types and I see steel stud wall assembles provide good numbers. Stud gauge isn't listed but I'm shore it matters ? I'm assuming heavier is better ? .............. If this is right would tube steel have even better numbers in a double wall assembly were 1 1/2"x1 1/2" steel is used in place of wood 2 x 4 s. This could provide an additional 4 inches of air space between studs , or do we measure " air space " from between sheetrock ? Anyone know of any draw backs to using tube steel ? Thanks, Tom ............. Still working on the photos.

Steel studs are more flexible than wood. This results in higher transmission loss. This is only beneficial in a coupled wall system (single stud wall)

Once the system is decoupled by means of double or staggered framing as well as resilient clips & channel, the benefits previously seen from the flexible steel are gone.

Additionally, a decoupled system does not benefit from further decoupling efforts. A staggered stud wall will not benefit from the addition of resilient clips (other than the side benefit of providing a deeper air cavity).

http://i657.photobucket.com/albums/uu291/ceilappeal/pretheater001.jpg

http://i657.photobucket.com/albums/uu291/ceilappeal/pretheater002.jpg

http://i657.photobucket.com/albums/uu291/ceilappeal/kevenyoung003.jpg

http://i657.photobucket.com/albums/uu291/ceilappeal/kevenyoung001.jpg

http://i657.photobucket.com/albums/uu291/ceilappeal/easter09045.jpg

Here is a better view of the room .On monday I go to see the space planner. Can't wait to see what he came up with................ http://i657.photobucket.com/albums/uu291/ceilappeal/pretheater005.jpg

There are many levels of sound isolation and acoustic quality. I'm searching for solutions to remodel this room to a sensible , well balanced combonation of size and sound...... The current floor joist are weak and have flanking problems. The floor must be replaced. This is where I,m weak ! I can achieve 6 inches of air space on all 4 walls ,This would give me a mere 11'6" width ( This is my starting point ). Ceiling air space isn't a problem . With these air space values could a raised concrete floor / room system be considered ?.........................WELL BALANCED ROOM = 6" AIR SPACE IN WALLS + ___ " THICK CONCRETE FLOOR + ___ " AIR SPACE UNDER FLOOR . 12" of air space under the floor would be fairly easy , Any more could be a challange.......... Has anyone come up with an equation or chart for matching these component values ?

Installing framing members sufficient to sustain huge weight loads in the ceiling, walls and floor would certainly give you an isolation advantage.

You would need a (local) engineer to sign off on the plans, though.

Engineering isn't a problem, I've got a local on the hook. Steel and concrete construction are right down my ally. I'm confident my flanking concerns could be redued to a hand full of hockey pucks. In order to take this theater to the next level the peramitors need to be dailed in, so my engineer has specific guidelines to work with. .... Post #6 mentioned sufficient mass over 12 to 24 inches of air space would be needed, (Depending on concrete slab diameter and weight) approxamately 19" could be obtained with relative ease. Wow, a 6" slab weighs about 15,000 lbs without the added weight of the floating room. Could we tighten these numbers up? A 4" slab is 5,000 lbs lighter. We need some of your expert number crunching here ....Yes a 20,000 lb. floating theater could be a life safty issue. This is a job that needs to signed off on.

You may find that you need new footings for this unusually high new load.

Without a doubt, I'll need footings. In order to determine the size footing needed, I'll first need to know the weight of a properly proportioned structure.

Just curious, maybe I missed this earlier in the thread. You are going to build a room in the back of the building photographed? Away from the glass?

a 4-6" ceiling slab, similar slab walls and a slab floor won't let much light in.

http://i657.photobucket.com/albums/uu291/ceilappeal/ted-1.jpg

Let me give you a little background. The queen and I decided we realy don't need five bedrooms. Permission was granted to turn the second floor into a modest master bed/bathroom and playground. The room pictured in upper link was used as a sitting room which featured a full view of an open lot and a couple quaint houses. Since the sixplex was erected in the lot we then had view of our six new neighbors. Removing the windows is no great loss.

Ideally, you would build a room within a room. The 4 walls, floor and ceiling would be independent and held up with 4 corner support columns within this space.

I'm not sure you could remove the existing floor system, considering the fact that the second story framing is sitting on top of it. Maybe you have balloon framing.

The building is a 100 year old brick building. The floor joist sit in wall pockets. The floor is comming out. The construction means and methods aren't a concern of mine. My current design thoughts include 6" air space in walls and ceiling anchored on a floating concrete floor. Not having a higher level of acoustic knowledge, I'm unsure of pad diameter in relation to available air space. For example, Would 19 inches of air space warrant 6 inches of concrete and 12 inches of air space require only 4 inchs?

You want to max both parameters of space and mass. There is no desired ratio. Any decoupled system will benefit from added mass. Any decoupled system will benefit from added cavity depth.

If the joists can be removed (thanks for that description of the building construction) then a complete free-standing room would work. Held up by 4 corner columns. Like a kids fort in the backyard

With my room diamentions a 6 inch slab weighs 15,000 lbs., where a 4 inch is 10,000. At what level do the benefits of mass tapper off?

With your goal of extreme low frequency isolation, the benefits do not taper off.

If you want to significantly isolate 30Hz soundwaves, you will need to get the resonance point of that floor to below 20Hz.

Offhand I'm not sure you can do that even with a 6" slab and a 12" air cavity. Terry has a program, maybe he could tell us.

You may find that you need new footings for this unusually high new load.

Well, actually, this could be beneficial. We added a room in an attic space. Sound isolation was critical. At the same time, the added weight required additional foundation supports and pilings. In the end, the pilings were designed to support the addition...the effect was to support this addition independent of the existing structure improving our sound isolation.

Terry, We would appreciate some of your expertise to clearify what will be the better combination of space and mass.

I suggest you contact Terry and retain his professional services.

You're dealing with a complex problem with a complex set of circumstances plus your own level of expectations. I believe you're beyond the "concensus of conflicting opinions on a free public forum" stage. Further, to do this correctly, someone has to spend some time and get into the engineering and architectural plans.

Dennis, Thank you for your input. Complex problem, okay. Complex circumstances, I don't necessarily see that (still gathering ug information), as for level of expectations I'm just looking for a sensible well balanced combination of sound x size (size being 12 x 17ish). I think it would be wise to have a better feel of possible job parameters, without a doubt this would stream line the engineering (structual, architectural, and sound) designing process. Maybe I'm still asking the wrong questions? What caliber of Quaility should be achieved in a small theather?

I don't believe you're asking the wrong questions. The issues are the lack of a complete picture (architectural plans and the like). By the same token, I suspect there's a lack of understanding on your part of all the issues, twists and turns that something like this entails (but you're learning!).

Dennis, I just read Theater through the roof (Ash Sharma theater). Nice job. I see you had 18" of air space, rubber pucks, standard subfloor, acoustik matt, 3/4" wood, gg, 3/4" wood, carpet pad and carpet. Acording to the article sounds like you came up a great system. Sure beats a concrete floor system from a means and methods stand point. I'm curious what is the perfered wood subfloor material?

OSB or other fiberous manufactured board ... not plywood. It doesn't like to lay flat.

There's a point which didn't come through in the article. To support the additional weight of a finished space, we had to add additional pilings (6' deep). The majority of the weight of the new area was therefore supported on a foundation separate from the house itself. (Since we had to do it anyway, we took advantage of the opportunity.

Excluding the theater floor what is the standard of floor sound treatment used in todays world? Currently I have 2x10 joist insulated with 9" of glass under 3/4" plywood. The 5/8" rock below isn't decoupled. Can I get away with just gg and 3/4" OSB, or is this not enough to support 3/4" T&G hardwood floors?