Noise Reducing Drywall

Hi Glenn,

I've no experience with this material, but surely they must have some data that compares it with other standard installations.

The issue of noise control is very multi-faceted, and what is being controlled: transmitted sound, reflected sound, low-frequency, high-frequency ... all have different requirements.

Comments here might just serve to confuse more than enlighten (and sorry in advance for that), but I can give you two vague comments about the subject. (1) an associate rebuilding a 'sound room' used a trademarked drywall material (I don't know the brand) and was not well pleased with the results. The cost of the 'special' drywall was apparently 'extreme', and according to him, the results weren't noticeable. (2) I've built rooms / walls specifically to lower transmitted sounds, both high and low frequencies, by actually building (how to describe) two stud walls that interfaced, so in effect, there was one wall, twice the studs, and every other stud was staggered forward and back. Effectively, wall side A was not directly connected to wall side B except at the floor and ceiling. Additionally, it's possible to simply cover the studs with strips of a damping material (there's a commercially available material called Dynamat

http://www.dynamat.com/

that works great, but you pay more for the name, and possibly there are alternatives), then simply secure the drywall to the studs with this material acting as an acoustic insulator. I've had good success with both these methods.

Again, Glenn, sorry if I've added more confusion than clarity ... just some thoughts.

Kind regards ...

_________________Dennis

I have not used "supress" drywall myself in any of my installations thusfar, although it has great STC ratings (50+ per sheet even 1/2") as opposed to standard drywall or plywood, etc. You can also look into Quiet Rock too.

But the most important thing here is the actual installation. If not executed properly it will be an expensive nightmare ! I have had my own people rip out a wall they got lazy about while I wasn't on site, skirting on my "csoulpro" protocol which involves the right materials in conjunction with each other and the right caulking and overlay process.

Insulation between walls is key also, and not your standard insulation will do. It is not about the "R" rating here.

A blend of density and space is the usual way to combat the beast of noise. We call "floating" a way of separating the contact between walls, floors, and ceilings. A layer of space acts as a beneficial layer in soundproofing because it dissipates sound waves as well.

The biggest problem in soundproofing is the amount of soundproofing you need and the actual space you have, meaning, if you have a small room to start with, then soundproofing properly is harder b/c it makes you reduce the room greatly.

Layering dense materials is the key, but all of this depends exactly what you intend to do in any given situation.

Are you trying to keep sound in or out ? What type of noise/sound is involved here and at what levels are you trying to inhibit ? How much of that is low frequency ? Do you care about losing space in the room ? Which walls are more important (are they adjoining walls to neighbors, etc.) ?

Soundproofing certain frequencies are easier than others, and isolating VIBRATION is literally another, as a subwoofer for instance in a 5.1 surround system is going to send that low freq vibration right through the floor, transfer into the cement/beams of any edifice.

"Soundboard" will not suffice in any situation, and materials like Supress drywall are superior but you must use these materials in the right configuration or else you will still have problems.

Sorry I am rushing through this, but if you need more help, reach out to me here or through my website, www.csoulpro.com. The one thing you want to do is soundproof effectively the FIRST time.

Several years ago, I decided to build a "jamroom" in my garage to be a place where I could play my electric guitar loudly enough to cause hearing loss, at any time of the day or night, without disturbing my neighbor. (I wrote about it a great deal on here and had a lot of input from others, but a search didn't find the thread???) The corner of my neighbor's bedroom was about 8 meters (I'm still trying to think in metric) from that area of my garage. I started with a garage that had only external fiberboard walls and the inner walls and the roof were unfinished with just bare studs.

The key principles that guided me were as follows:

M. MASS--Sound is dampened by having to pass through mass, thus the more mass, the more the dampening.

I. INFLEXIBLE--Sound is more efficiently transmitted through rigid structural elements, thus, avoiding a rigid structure, wherever possible, was a good idea. I considered the structural elements that might transmit mechanical energy and the directions of propagation, and sought to ensure that the energy would get dissipated as efficiently as possible or propagated into adjoining structural elements as inefficiently as possible.

L. LAYERING--In general, mechanical energy is less effectively transmitted when it has to propagate from one structural element through another structural element of a dissimilar material.

F. FREQUENCY--The mechanical energy has to go somewhere, but by maximizing the number and range of the natural harmonics of the many, disparate structural elements, I could maximize the degree to which the mechanical energy absorbed would be dissipated within the structure via destructive interference.

NOTE: Though maybe not obvious from the foregoing, it is imperative to avoid holes and gaps, because sound will find them and pass through.

Thus, by scrupulously applying the above-referenced MILF principles to the maximum extent, the main elements were constructed as follows:

1. FLOOR--I determined that I needed to isolate the inner floor from the slab. There are a variety of ways to do that, but here's what I did. I had 5-7 gallons (er, 19 to 25 liters) of unneeded latex paint, so I mixed it with some unneeded popcorn ceiling texture, put down a perimeter of wooden studs, and poured the paint on the floor. When the paint had cured enough to walk on, I put down a grid of wooden studs, without connecting them to each other or to anything else. On the tops of the studs, I ran a thick bead of latex and let it set. Then I put down a subfloor of 19 mm plywood flooring, with each sheet separated by a 3 mm gap and the perimeter free. I filed the gaps with a bead of latex.

On top of that, I ran a 6 mm layer of cork sheeting, a layer of dense, premium carpet foam padding, and finally a good quality carpet on top. When finished, the floor supported walls on three sides, with each of those walls being inner, floating walls. The back wall, facing away from my neighbors and out toward the undeveloped woods along Buffalo Bayou, was less critical, and I did not build an inner wall there, but did take other measures. Even there, my floor was not structurally connected to that wall. Thus, between the concrete slab and my room, sound waves had to pass through thick carpet, thick foam pad, 6 mm of cork sheeting, "floating" sheets of 19 mm plywood flooring, a layer of latex, a wooden stud, and a thick (3-5 mm) layer of latex paint.

2. INNER WALLS--the room had three inner walls that were built upon my elaborately constructed floor. Each of these walls was made using sheet metal studs, because they resonate less efficiently than wooden studs. The bottom horizontal run was placed right on top of the carpet of the floating floor. I left a 5 mm gap between the top and the ceiling structure. Also, I did not allow the vertical studs to bottom out into either the top of the bottom horizontal channels. That is, I left an 8 to 12 mm gap at each end of the vertical pieces. I then glued strips of 6 mm cork sheeting onto the vertical studs and attached horizontal strips of sheet metal over the cork using sheet metal screws into the metal studs.

The wall that faced my neighbor's yard was set up so that it would be about 1 cm per 30 cm off of parallel from the existing garage wall. Also, the longer wall at the front was similarly built to be off parallel from the back garage wall. The two non parallel walls were intended to reduce reverberation between opposite walls inside.

After that, I attached a layer of moisture resistant 16 mm sheetrock (the moisture resistant sheetrock is also a bit more dense and seemed like it would resonate less efficiently) with sheet metal screws screwed into the horizontal sheet metal strips, halfway between the vertical studs. I left a 12-15 mm gap between the bottom and the floor and top and the ceiling. Then, I ran thick vertical beads of latex, attached strips of the 6 mm cork sheeting, and then a second thick bead of latex along the cork. Before the latex set, I lightly pressed on a second layer of 16 mm moisture resistant sheetrock, perpendicular to the first layer, and used a few screws to tighten it up enough the spread the latex a bit, but not enough to squeeze it out. When the latex had set, I removed those screws. I left a 3-5 mm gap between each panel of sheetrock and filled it in with latex.

Thus, sound waves from inside the room absorbed by a panel of sheetrock encountered a rigid sheet that had a rubbery, latex border all the way around the edge, thus not likely to efficiently propagate mechanical energy to adjacent sheets of the same layer. Also, because they were not rigidly connected, the resonances would be slightly out of phase, partially cancelling each other out. Also, to propagate through the wall, the panel would have to conduct absorbed energy through a 1-2 mm thick layer of latex, 6 mm of cork, another 1-2 mm of latex, a horizontal strip of sheet metal, the vertical metal studs 12" to either side of the point of contact, and then the same elements in reverse on the other side of the wall. Thus, my inner jamroom walls had 4 layers of 16 mm sheetrock--2 on each side, each layer perpendicular to the other, and a lot of flubbery stuff in between the facing flat surfaces and around the edges. I filled the gap at the top, where it approached the ceiling, with a thick bead of latex on each side. Also, on the inside, I put 10 cm thick batts of fiberglass insulation. All adjoining rigid elements were connected so that sound that mechanical energy would have to travel a maximum distance, propagate through layers of flubbery stuff, squeeze through minimal points of contact and then repeat before vibrating the adjacent piece. Also, the overall effect was to multiply the natural harmonic frequencies and maximize destructive interference.

I had to put the doorway in the wall facing the garage door (it would just have been silly to put it anywhere else), but I used techniques similar to those described above to make the connection between the doorframe at the other structure sound without being exactly rigid. Also, I installed a foam filled metal door.

3. CEILING--Here, I had to compromise a little bit, as I wanted to retain as much height as possible without having to rip out the existing joists. Thus, I latex bonded cork strips to the wooden joists and ran strips of sheet metal over that and perpendicular to the joists. I then ran a thick bead of latex over the cork before attaching a layer of the 16 mm sheetrock to the strips using self-tapping sheet metal drywall screws, taking care to put the screws through the sheet metal strips between the joists and avoiding screwing the sheetrock directly into the joists. Again, I left 3 mm gaps around each edge and around the whole perimeter, which I filled with latex.

After that, using the latex, I attached a grid of 6 mm cork squares about 60 cm apart, added latex to the cork, and then squeezed thick humps of latex in a grid across the ceiling sheetrock, and in between the squares of cork. Before the latex set, I screwed another layer of 16 mm sheetrock onto the first one and perpendicular to the first. In doing so, I took care not screw the sheets together too tightly, just snug enough to squish the latex a bit. When the latex had had time to set, I removed the screws.

Thus, I two layers of sheetrock joined and held separate by latex and cork. Those two layers were attached by screws in between the joists to sheet metal strips perpendicular to the joists.

On top of that, I took rolls of tough, nonwoven fiber fabric, intended as a weed barrier for ground cover, and draped it over the joists. I let it hang between the joists so that it wouldn't quite reach the sheetrock. I then put down a plywood floor on top of the joists (getting some extra attic space) and blew in as much cellulose insulation as I could pack in using a rented blower. Thus, I had some dense insulation above the ceiling without any appreciable direct contact or weight on top of the sheetrock ceiling.

4. OUTER WALLS—Along the side of my garage that faced my neighbor's property, I insulated the bare stud garage walls with fiberglass batts, added a thick bead of latex to the wooden studs, and attached a layer of sheetrock with screws. Then, I glued another layer on with latex. I left an airspace gap between this outer wall and the adjacent inner wall of my jamroom. The gap varied from 2 cm (at the back of the garage) to 15 cm (at the front). Thus, there was no direct, rigid physical connection, through the concrete slab, the walls, or the ceiling, from the inside of my room to the outer wall. The reason the airspace gap varied from 2 to 15 cm was so that the inner wall on that side would not be parallel with the opposite inner wall. This was done, as I mentioned previously, to lessen reverberation between the opposite ends of the room.

Along the front of my jamroom, I built a load-bearing wall (to better support my new attic and to keep the ceiling from sagging down onto my floating jamroom). Here, I used wooden studs, attached conventionally, but also insulated between the studs with fiberglass batts and added two layers of sheetrock on each side. As with the side that faced my neighbor's yard, the front outer wall was about 1 cm per 30 cm off parallel with the inner wall, but was square with the outer garage walls. Thus, for sound to get out of my jamroom, it had to pass through the four layers of sheetrock on the floating wall, transit an air gap, and then pass through an additional four layers on this second wall. Even then, it would still be in an area inside my garage, as the jamroom took up only the back two-thirds of my garage.

On the side of my garage that faced away from my neighbor's yard, the inner wall was a non load-bearing wall made of sheet metal studs and four layers of sheetrock on top of the floating floor. This wall was about 100 cm away from the outer garage wall. I insulated and double sheetrocked the outer side wall and the back and put in a door at the front, to create a 1 meter by approx. 4 meter storage closet—another benefit of my project, in addition to the new attic.

5. GARAGE DOOR—My existing garage door was uninsulated sheet metal and in poor condition. Thus, I sprung for a new sheet metal door with foam insulated panels and sheet metal on the inside, as well.

6. CLIMATE CONTROL—By now, you might be wondering what measures I took to control the inner climate. Well, Johnny Jim, I'll reveal that, as well. I discovered a cooling/heating system known as a "split system." It's like a central a/c and heat unit, but without any ducts. The condenser and compressor portion sits outside and the evaporator, blower, and controls—in a unit the size of a big city Sunday paper—attach to an inner wall. Between the two units, you need only make a 6 cm hole for the two copper refrigerant lines, the power wires, and a drain hose. It's a beautiful thing! I didn't want to use a window unit, because a large hole in the wall would have defeated much of my effort to contain the sound. Also, a window unit includes the noisy compressor right in the room with you. I wanted to get loud in there with my guitar, but I didn't want other sources of noise. I found a ¾ ton (not sure what the metric equivalent is) system on Ebay for about $745 shipped and including all required parts—even a remote control. I believe that it was made in Israel. Other than the fact that the universal symbols on the remote are non obvious and the word "clock" is spelled "colck," I am extremely pleased with the system.

In fact, because my jamroom is so thoroughly insulated (I could probably have kept it cooled with a large glass of iced tea) and only about 60% of the area recommended for the unit, it is too efficient. That is, it doesn't run long enough to adequately dehumidify. Thus, once I noticed water condensing out of the ceiling and dripping onto the carpet (possibly mostly from water vapor outgassing from the huge quantity of latex I used), I ran out and purchased a dehumidifier.

7. INTERIOR—Once I had the room built and painted, it was so effective at containing the sound, even despite the non parallel opposite walls, that a sharp noise took over 10 seconds to decay. To address the inner acoustics, I draped heavy cotton moving pads on one end and one side wall. I bought cylindrical bass traps to put in each cornet at one end. I added dense foam corner treatments to each upper corner at one end. Beyond that, I brought in book shelves and filled them with guitar, amp, and music books and magazines, brought in a futon, added a wrap-around work table at one end, and brought in additional sound absorbing clutter and other leftovers from my pre-marriage days that my wife wanted out of the house anyway (including boxes of pictures, homemade video, and other memory-trapping materials that pre-dated our relationship).

RESULT—The room I designed and built performs great. Only my very loudest amp has enough oomph to be heard by my neighbor inside that closest room. Even then, it is only barely audible and only when it's volume is maxed. That amp, by the way, I built mostly from scratch and named the "Twin FrankenVerb," because it is based on a 60's Fender Blackface Twin Reverb, but with some differences that make it probably 10 db louder (e.g., a much beefier PT, excess filter capacitance, more efficient speakers, etc.). In fact, my ears are still ringing from a brief test session I did three years ago. Say what?? No, really, say what??

In retrospect, I probably overengineered the room by about 4,700%. Really, I could have gotten away with much less overkill and spent much less money, if I'd just persuaded my neighbor to let me pay to have good-quality, double paned windows put in that part of their house. It was a lot of fun, though, and kept me off the streets for most of a year. I only hired help to bring guys in to tape and float the inside, because I hate that finish work. All the rest, I did myself with the help of two of my brothers. Actually, I one of my brothers was between jobs and I paid him for one week's worth of work on some of the construction. That worked out well for both of us.

COST—Yikes, I hate to think about that. Though I started a detailed spreadsheet to track the cost, I gave it up after awhile. I would estimate that, all told, I probably spent $8,000 to $9,000 for a super cool 3.75 m X 5.5 m insulated jamroom, a handy, secure storage closet, and a new attic. The spiffy new garage door doesn't really count, though, does it?

BENEFIT—I still can't play the guitar very well. Mostly, I play quietly inside the house (or relatively so, depending on how willing I am risk--or how much I intend to—annoy my wife and kids). I play guitar in my jamroom occasionally, usually during the evening, and not usually all that loudly. Thus, it might appear to have been a largely unjustified construction. However, my 12-year-old seems to want to play the drums (I put a Roland electronic set out there) and my 6-year-old likes keyboards, drums, and guitars. Between the two of them and their friends, the room with likely spare me much of that noise. Hey, maybe they'll even invite me to join in from time to time.

CODA—(From a future news broadcast) In recent news…local authorities are bewildered by a strange and bizarre event underway in the suburbs. Apparently, one local man's effort to install a jamroom in his garage involved such vastly and densely detailed and exceedingly overwrought analysis that the effort and resulting thought pressure that has propped it up all this time has finally given way with disastrous results. The room has begun to implode upon itself and experts cannot give any reason to expect that the process will stop before it reaches singularity and have expressed concern that it may inevitably consume the entire universe. Meanwhile, in other news…