Best way to sound dampen and setup new building

Discussion in 'Home Theater Projects' started by Brian Beecher, Apr 21, 2006.

  1. Brian Beecher

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    Hi everybody. I have a garage that I am closing up and finishing the inside for some workspace/officespace. There is a wooden building connected to the garage that I am also planning on finishing the inside for use as a theater room. The room is 17 1/2 x 11. It is actually not built on a concrete slab, it's off the ground a little bit. I know some sound will go through, but I want to keep it as muted as possible outside the building. There is only one neighbor and they're a pretty good distance away, but I'm more of a night person so I don't want people to be bothered by sound at midnight. Does using thicker drywall or any special insulation help at all? As for the flooring I have some left over laminate wood to use. Is there anything additional I can put under the laminate besides the pad to dampen sound a bit? I have a pair of Rocket 750's up front and I'm working on the rest right now. Thanks for any input you can offer. I'm sure I'll have a couple more questions before I get started, so thanks a lot!

    Brian
     
  2. Jay Mitchosky

    Jay Mitchosky Producer

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    The best way to isolate sound is by building a room within a room. Separate joists on an inner frame that do not make contact with the outer structure (with the studs offset compared to the outer structure). The ceiling joists are hung from the inner frame and sit between those in the outer structure, again without contact. This eliminates (or dramatically reduces) vibrations being transmitted from outside the theater proper.

    For drywall use two layers of different thicknesses with the seams offset. Some sort of acoustic caulking should be used at the joints. You may also opt to use resilient channel to further isolate the drywall from the studs. Both the inner and outer frames are stuffed with insulation, leaving an air gap between. You may also use a product called Acoustibloc which is a heavy lead-like sheet (available in rolls) that you run between the inner an outer structures.

    For flooring you can by acoustic padding that would lay under the floor proper and isolate vibration. The floor itself would not make contact with the side walls again so vibrations aren't transferred. You can also buy 4x4 tongue-and-groove plywood flooring squares that have a rubber base at the bottom. Like putting together a big checkerboard and this will provide some cushion to absorb sound. It will also add somewhat to the surround experience as the floor will have movement from the low frequencies. Again, don't connect to the side walls.

    All openings like lighting cans and gang boxes need to be sealed with acoustic caulk. All of the above will be compromised if you have little nooks leaking sound.

    The biggest hole - the door - will be your weakest link. You'll be looking for heavily insulated to help limit sound transmission. But all of the above will dramatically reduce any sound transmission in or out of the theater. Will be quite expensive and time consuming but that's your starting point for isolation - work backwards as time and budget allow.
     
  3. JeffCar

    JeffCar Agent

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    Jay,

    Not trying to hijack the thread, but you mention something amongst the typical recommendations for "soundproffing" a room.... the doors. I began with the above recommendations in mind, and not so quickly came to the realization that doors are probably the weakest point of ANY room. I scaled back my room plans when I realized the high chance that resilient channel is defeated either in construction with an errant nail (or shortly after when I inadvertantly have a nail contact a stud rather than the RC). I also looked into the option of something like QuietRock, which seems to be an excellent product, but is a significant investment in and of itself, and the doors still were a problem. I have yet to hear much conversation about what I believe is the WEAKEST LINK in the room... the doors. I think I have done a reasonably good job at isolation (2x6 staggered stud with a layer of 5/8" and 1/2" glued and screwed). I did not go with a room within a room as it just takes too much of the available space, as well as makes construction very complicated. Again, without spending thousands on doors, is it really worth that kind of construction technique?

    Just some random thoughts... again, Brian, I did not mean to hijack the thread. Just make sure that you realize that you must look to your weakest link before you beef up your defenses and increase your costs dramatically in one area of your room.

    Jeff
     
  4. Jay Mitchosky

    Jay Mitchosky Producer

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    Jeff

    Great question and observation: Is it truly worth it? When going down the "path of isolation" you need to keep these things in mind. I'll relate the same story I've used several times in this forum: Widescreen Review's HT lab at their office in Temecula, CA. This is an example of what you can achieve when all the pieces (including the door) are in place. We were there on an HT meet a few years back and the experience still stays with me. Gary Reber (editor-in-chief) was demonstrating Air Force One (among other titles) in the reference room. I left for a pitstop, right around the scene where the fighter plans intercept AF1. All hell was breaking loose in the theater, but when I closed the door there was nothing on the outside. I've compared the most EXTREME low frequency impacts during that scene to be little more than a balled up sock dropping on the floor when outside of the room. And this was at reference level. Astonishing. Now the caveat: their door is about a foot thick. Spec'd for recording studios and such. Cost: God knows what.

    So total isolation is available but you need the budget and expertise to afford it. Beyond that you need to choose what's important and just how quiet you actually need. If you're not willing to go all the way then many of those isolation techniques will be limited in result as the weakest link will always prevail. There will be incremental improvements but to manage expectations one always needs to consider where sound is going to leak out. At the end of the day an quasi-isolated room with a standard insulated door will be quieter than when similar techniques aren't employed.

    You can start trimming the specs with single wall but double drywall, or single wall/single drywall plus Acoustibloc, etc. Every little bit helps.
     
  5. Brian Beecher

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    Thanks for the info Jay. My problems are a limited amount of funds for the room plus the size of the room is a bit tight. Being 11 1/2' wide, the room is already a little tightfor the syuff going into it. Doubling the walls will cause me to lose space that I am already short on. The room also has an open hallway about 30" on the back wall off center a bit. I know it is certainly not ideal at this point, but what would you recommend to make it as solid as possible with my limitations? Is the acoustic padding easy to find at a local hardware store or do you have to order it? This room will have plenty of sound that escapes, but if I can do a little bit better than just drywall and regular insulation I'd like to do it. Again, thanks for the help.
     
  6. JeffCar

    JeffCar Agent

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    Brian, it sounds like you are in the same boat as a lot of us folks.... want to do the best you can but have certain limitations. My focus would be on building mass. I would go with two layers of drywall (you only lose 1/2 or 5/8 depending on your choice of thickness) with a product called green glue in between. The green glue dries to form a sticky elastic bond and creates a bit of separation between the panels of drywall which helps with sound dampening. The product Jay refers to above is one of a number of mass loaded vinyl type products..... they are relatively expensive and are less than easy to install for the typical DIY person. The product is both heavy and difficult to handle without help IMHO. There are products out there that actually have the viscoelastic layer built into their product (Quietrock is one that pops to mind). They are very effective and install like regular drywall, but you will have to remortgage the house to afford it. I would go with the though process that density is your friend, and you won't go wrong. Good luck!

    Jeff
     
  7. Brian Beecher

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    Thanks Jeff, that sounds like it's more in the realm of my budget right now. That should do a better job with the walls, but the floor is probably the weakest area. Right now it is plywood and the building is about a foot off the ground. Would something like this work- Seal every joint in the existing plywood, add some type of acoustic padding, a thin layer of plywood over the padding, then the laminate padding over that with the laminate wood flooring on top?

    Any suggestions on a good cost effective brand for the padding?

    Thanks again,
    Brian
     
  8. chris_everett

    chris_everett Second Unit

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    There are three keys to soundproofing

    1. Airtight
    2. Dense wall partitions
    3. Accoustic Separation

    Airtight is fairly obvious. If the room is not airtight, sound will escape. This is also the first step toward soundproofing.

    Dense wall partitions can be accomplished with mass-loaded vinyl, multiple layers of drywall, and so forth. Heavier walls take more energy to vibrate, and are more soundproof as a result.

    Accoustic separation is things like double wall construction and resilient channel. Be separating vibrating components from non-vibrating components, soundproofing increases.

    An ideal room will utilize all of these techniques

    Doors:
    As already pointed out, doors are the weak spot in most any soundproofing project. For those on a budget, I recommend a solid core wood exterior door, and a good threshold. This is reasonably inexpensive, and more effective than you might think. Make sure and caulk the heck out of the door jams, and make sure that the threshold is good.

    Soundproofing is an incremental job. In my theater, my wall sandwitch is as follows

    Inside of room
    1/2" drywall
    1/8" Mass loaded vinyl
    5/8" drywall
    Foam tape on studs
    2x4 studs/Normal thermal insulation with mineral fiber insulation in room weak points
    1/2" drywall(or plywood on exterior wall)
    Outside of room

    My door is as I described above. In spaces immediately adjacent to my theater (outside, my garage, a closet and a bathroom) you can hear loud noises in movies. Beyond that, it's dead quiet. I have about a 45db reduction in volume, which is more than adequate for me. Depending on where your theater is located, you may need more or less.
     
  9. JeffCar

    JeffCar Agent

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    I don't have a suggestion for padding under the laminate flooring, but be careful getting too think a pad under there... laminate floors don't like a base that moves, although it is certainly more tolerant than tile. There are a couple of potential approaches for the floor....

    You could lay sleepers (2x3s or similar), insulate the floor with rock wool or something (rigid fiberglass?) and lay another layer of plywood (3/4) all sealed up nicely over the top. Same concept as the walls... more mass is better. Even if it is only another layer of 3/4 plywood put down over the existing floor which you seal up tight, you are ahead of the curve. Hope this helps!

    Jeff
     
  10. JeffCar

    JeffCar Agent

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    I don't have a suggestion for padding under the laminate flooring, but be careful getting too think a pad under there... laminate floors don't like a base that moves, although it is certainly more tolerant than tile. There are a couple of potential approaches for the floor....

    You could lay sleepers (2x3s or similar), insulate the floor with rock wool or something (rigid fiberglass?) and lay another layer of plywood (3/4) all sealed up nicely over the top. Same concept as the walls... more mass is better. Even if it is only another layer of 3/4 plywood put down over the existing floor which you seal up tight, you are ahead of the curve. Hope this helps!

    Jeff
     

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