Sound isolation panels over existing drywall idea

[pianomidget]

I am working with a home studio. My goal is to isolate sounds of loud vocals and electric guitars to the point of not disturbing others ' sleep. A "turbo" fan will be on in the rooms of sleepy bears as white noise.
I'd rather not modify and reconstruct my existing walls. So here's the idea. Imagine (placed over the drywall) a plywood layer with padded carpet on one side and vinyl tile on the other with fiberglass insulation fastened to the back with shrink wrap. These will be held to the wall by wires pulled tightly and anchored to the drywall by toggle bolts (picture the wire NOT connected to the plywood; it runs along the ouside face). Why vinyl tile? Auralex is advertising a vinyl material for sound isolation.

WALL MAT'L SUMMARY (from room to drywall):

carpet > padding > plywood > vinyl tile > fiberglass insulation

I have also been thinking of placing a layer of cork between the plywood and tile.

This concept has been on my mind bearing in mind the following:

1) Funds are limited

2) Hardworking individuals can save via do-it-yourself

3) I desire to keep as much space as possible in this bedroom-sized studio (about 10' x 11' x 8').

Is this the dumbest idea ever or what? I'm new to this world of studio know-how and looking to build a space-effective, cost-effective way to sing privately as well as to keep sleepy bears dreaming.

Thanks,

David

[Sword9]

Seems to me that more layers of drywall would be cheaper and more isolating than carpet. Not to mention the fact that vacuuming walls is no fun.

If it's not air tight though, isolation is not going to be much better either. So you should look for solutions for ceilings and floors too.

The experts on here will be able to give a better help probably, but I thought I'd chime in a bit since I saw your post. You might be better off with a vocal booth of some kind. HTH.

[cadesignr]

Application of carpet and padding to vertical surfaces is a fire hazard. It also offers very little in the way of sound loss, but will absorb high frequency to the extent your recordings will sound dull and lifeless. Application of plywood and vinyl tile, while appearing as a cheap solution, in reality, especially the method of atta barriarchment, will actually REDUCE your sound transmission loss, as you are puncturing one leaf of the assembly, with NO way to seal it.
Here is the reality. Many people try to circumvent tested solutions with what they THINK will beat years of experience and proof via tests. Bottom line, gypsum board mass is the CHEAPEST and easiest way to improve transmission loss PERIOD!!!!!! What you are saying, is in your limited exposure to the science of sound transmission, you have come up with a way to improve the experts solutions. Wrong. You are only fooling yourself, and will waste time and money. I suggest you read everything you can, and then some, BEFORE you do this. Last, your solution at best, will also REDUCE Low frequence transmission loss, by ADDING more leaves to the existing assembly.
If you TRULY want to succeed at this, my suggestion is this. For the size of this room, compared to the price of carpet, padding, plywood, vinyl tile, and all the work it would take to assemble this and HANG it, you could purchase TWO layers of drywall AND Resiliant channel. Since you are already predisposed to drilling HOLES in your existing drywall, I would suggest this. For Resiliant channel to be effective on a TWO leaf assembly, there MUST be insulation in the wall cavity. There also needs to be as large an airgap between the two leafs as possible. Therefore, this is what you would need to do. IF there is EXISTING insulation in the wall cavities, you could get away with mounting RC directly OVER the existing drywall, but ONLY if you drill a few 5" holes through the existing drywall at EVERY wall cavity. This allows for the assembly to REMAIN a two leaf assembly once the new drywall is installed. However, IF, there is NO insulation in the walls AND ceiling, you need to REMOVE ALL OF IT and install batt type insulation. THEN, apply resiliant channel directly to the studs and apply TWO layers of 5/8" drywall. However, there are many details to this solution which MUST be addressed for it to be successfull. They have been addressed many times here. Door jambs, doors, windows, HVAC ducts, electrical and other issues are but a few. Each requires attention to detail, not to mention the actual application and installation of the RC/drywall themselves.
Also, the issue of structural transmission may have to be addressed. Structural wood floors act like a diaphram, and transmitt to other structural elements accordingly. And if there are floors above, well, now we are talking other elements to be delt with too. You have told us very LITTLE, so at best, one can only guess at your conditions.
I hope this doesn't dishearten your attempt at economical STL design. Many have attemped to do the same, only to discover the realitys of isolation construction. Believe me, this stuff is NOT intuitive, and sometimes seems contradictory to common sense. However, I assure you, physics doesn't give a damn what you THINK, regardless of your common sense. If you are still interested in pursuing this to a successfull conclusion, tell the forum EXACTLY what your room is comprised of, the type of existing construction and wall/ceiling materials, doors, HVAC etc, and I am sure you will recieve excellent advice on how to proceed. This may NOT be as economical as your budget allows, however, I guarantee, IT will not waste your time or money as your intended solution will. Not to mention the detrimental acoustics. That is a WHOLE 'NUTHER ANIMAL!
fitZ

[pianomidget]

Thank you for your input, cadesignr. FYI I seek to STL treatment to only two walls in a single-level home with a carpeted floor on a concrete foundation.

[cadesignr]

Hello David. Ok, first off, I want to make something clear. I am no expert at this stuff. Just a somewhat enlightened enthusiast myself. It is in that context that I offer what I know. I just hate seeing people waste their hard earned money and time on things I feel will not work. Maybe someone else will disagree with my evaluation of your intended solution. Untill someone does, I firmly believe I am correct. And now, you have offered some new information. But actually, there are some things you need to understand.
Isolation is a wierd thing. One mans interpretation of what is "good enough" may be another mans "sucks". In that context, your statement:
"My goal is to isolate sounds of loud vocals and electric guitars to the point of not disturbing others ' sleep.
tells us very little. For instance.

How loud is "loud"? Electric guitars have an extremely large dynamic range. That is the problem. One mans loud may be another mans quiet.
And where are these people sleeping? In an adjacent room? Two rooms away? At the other end of the house? Are the HVAC ducts common to these rooms. Are they connected by a hallway? Are there doors connecting these sleeping areas to the space in question? If they are adjacent, what are the existing walls made of? Are the ceiling joists common to both rooms? How about electrical outlets, any common outlets to one wall cavity between this space and an adjacent room? Any exterior walls? Are you concerned about sound transmission to the outside world?
Any insulation in the attic crawl space?
These are SOME of the type questions that must be addressed to fully understand your conditions. Simply piling mass on to the two walls you mention, MAY do absolutely nothing, as structural transmission via the other walls and ceiling and floor may totally negate that type of solution. In fact, I'd bet money on it. Not to mention common HVAC ducts between rooms if they exist. So, the best thing I can advise at this point, is to tell us as much as you can about your conditions. Otherwise, you are asking people to simply approve or disapprove of your ideas. I tried to offer another solution, however it was spitting in the wind without knowing what you are really dealing with.
fitZ

[pianomidget]

Since I am still two weeks from moving in to this house-- here's what I can tell you at this time:
By "loud" I mean screaming volumes (i.e. go into that room and scream for me, please). The sleeping areas are not in adjacent rooms. One will sleep in bedroom two, which is down a hallway (about 12'). A bathroom separates bedroom two and the studio. Bedroom two and the studio doors open into the hallway, facing each other (about 12' apart). The master bedroom is on the other side of the kitchen and family room (split floor plan). I believe the HVAC ducts are common to the bedrooms, as this is single-level 3 bd, 2 ba. Primarily I'm concerned with STL on the two interior walls (other two are exterior). I don't believe that the ceiling joist are common to br 2 and the studio (I did look up there, but not for that reason). Blown insulation is present in the attic crawl space; I will be adding more insulation to maximize energy efficiency.

Thanks,

David

[cadesignr]

Primarily I'm concerned with STL on the two interior walls (other two are exterior).

Hello David, thanks for the info. Well, as a person who deeply understands budget restraints, I also have been forced to try things that common sense told me would work. However, outwitting physics is an exercise in frustration, to say the least. So, this is a brand new home, which I assume has FINISHED walls in the studio, so the thought of tearing off brand new sheetrock is probably irritating. And I don't blame you. But you need to make a choice. Either to guarantee success or take a chance on half baked solutions. There are no other options. However, taking a risk on failure is both expensive and time consuming if indeed it fails to meet your goals.
In my opinion, to guarantee you meet a target STL, you have to bite the bullet and use solutions that are tested and classified to meet it. At this point, it would be difficult at best to outguess flanking paths via the structural transmission through the ceiling and exterior walls, so my best advice would still be to de-couple all wall and cieling membranes via RC, and 2 layers of drywall. I already told you what this would intail though. Not an easy bullet to bite.
Even then, it only succeeds at a RATED STC if every detail is painstakenly addressed, and all the weak links are matched to this RATING, like doors, electrical, ducting etc, which in reality may STILL not be enough. That is the problem. Without MEASURING the sound level in both the studio and the bedrooms while playing and singing at the levels stated as "loud", and THEN, guessing the db threshold that an individual will be woke up, you have no way of determining exactly what level of transmission loss you are trying to attain. That is why only you can determine this! Ultimately, to absolutely guarantee containment, the usual method of choice is floating room construction with massive membranes, as this is total decoupliing of the space from the adjacent structure. However, it is EXTREMELY expensive.

The ONLY other option is pure conjecture. That would be to simply add mass, which in my mind would imply at LEAST 2 more layers of drywall to these existing two walls. It would do no good to open these up and use RC as you would be wasting your time. And it could feasably turn out that this will NOT achieve your goal. Who knows though. Only you can determine if it succeeds. I believe you will need to address the doors though too. Usually, these are hollow core, which are excellent sources for sound transmission. If it were me, I would change BOTH doors to solid core, and at LEAST use weatherstriping on the studio door, if not rubber seals, AND a threshold with a seal on the bottom of the door. If possible, I'd even sheetrock the ceilng too. But again, this may not be enough. Hence guesswork vs guaranteed STC via measurement of source levels in the spaces you are trying to isolate.
Well, I hope this helps illustrate what you are up against in this quest. It is not easy to contain high SPL under the best of circumstances. Even more difficult if you only have a limited budget among other restraints. But again, this is ONLY my .02.
fitZ[/quote]