Sound Proofing

[Begle1]

I am moving into a new house and would like to sound-proof a study/theater room. Any body have any ideas as to go about this? The main limiter is the cost of the soundproofing and the fact that the soundproofing must be applied on the exterior of the wall. Thank you for any help.

[Troy]

Take a look at these articles and let us know what you think:

http://www.soundonsound.com/sos/feb98/articles/soundproofing.html

http://www.soundonsound.com/sos/mar98/articles/soundproofing.html

http://www.soundonsound.com/sos/apr98/articles/soundproofing.html

http://www.soundonsound.com/sos/may98/articles/Soundproofing.html

You should also check out absorption levels of different kinds of insulation. Anyone know anything about that? Drywallman?

Sounds like a fun project, keep up posted!

[Begle1]

So the cheapest and best thing to do is to layer an inch of plasterboard to the existing walls, then put shutters over the windows and doors? That would work, but I would have to put panelling over the plasterboard to aviod it from looking like sin. Maybe I could put some of that egg-container stuff over it. I could put regular fiberglass insulation above the room in the attic...

Thank you. Have to have an idea quick.

[Drywallman]

http://soundproofing.org/infopages/channel.htm

Here is some information that I would recommend you read.

If you have any interior walls, that are not insulated, I would suggest calling your local insulation company and have them blow in insulation between each stud.
Nail your resislent channel to the existing drywall and hang with sound board.

Any other questions please feel free to eamil me at JASDRW@AOL.COM

[Fix-it]

Sound absorption requires lots of mass. The big prob. is the bass freq.'s traveling thru the foundation. Insulate the walls heavily and keep your sub on the floor on a padded footing.

pm me directly if you have more questions. I do this stuff all day long.

[NPBSurfr]

There are a bunch of factors here.

First off, if it’s a second floor, I would recommend putting ¾”-1” cement subfloor. Check your building plans, and measure the capacity of your building if so.

Second of all, there are so many methods out there! Here’s what I’ve done for stacks in 3 – ½” stud walls; I’ve placed soundboard 3’ - 6” from floor, then place 5/8” gypsum 4” from floor on top, filled the void with insulating foam, then another piece of soundboard 4’ – 6” to the ceiling, drywall from there to the ceiling, poked a few holes to fill with foam, and walla!

In your case, I would just fill the walls with solid insulating foam, soundboard, 5/8” gypsum, then a good heavy, thin and stylish carpet over that for absorption and reflection.

It’s a lot of effort, but well worth it. Best of luck!

[Ted White]

There are high performance ceiling applications that are particularly good for footfall noise as well as airborne. Generally they will involve these elements:

Decoupled framing
Absorption (insulaton)
Mass (standard 5/8" drywall)
Damping

Your best success will come from using all 4 of these elements.

[Sensible]

More on soundproofing and sound control

The others have covered the subject well, and hopefully you've long since built yourself a lovely home theater by now, but one thing in your initial follow-up is concerning:

> layer an inch of plasterboard to the existing walls,

As others replied, try to avoid attaching anything rigidly to anything (while respecting the need for structural soundness, of course). Soundproofing comes down to a combination of mass and isolation. Even a small airspace helps. Ideally, make a "room within a room" by elevating the floor on cushioned studs, hanging the ceiling, and building detached interior walls. (If you were building the wall from scratch, you'd want to use two sets of studs -- one for this wall, one for the other room.) However, I'm not sure what fire and building codes have to say about this. It might be that "hidden" spaces pose some concerns.

Then, while dense insulation may provide some additional mass, its main purpose is to stop reverberation within the wall -- so that any sound that gets in is quickly squelched. Rigid insulation might even be hurtful, I'm not sure.

If possible, the rooms' wall outlets should be staggered, so that sound can't flow from one room to the other, and seal the tiniest holes. Use the minimal number of attachment points and fasteners (again, be consistent with sensible constuction practices) -- each solid connection is a path for sound to travel.

And if possible, incorporate non-parallel surfaces. (The perfect room is not necessarily a square or rectangle.) That reduces the reinforcement of one particular frequency. If your neighbors are so noisy (or sensitive) that you need to treat your windows, an old trick is to include a third pane of glass between two others, angling that interior pane so all three aren't parallel.

Then, within your room, again you should control reverberation by using soft materials, but don't overdo it. You're building a theater, not a sound studio. And even those differ from one another in their needs. If the room is "boomy," some upholstery (or a bit of carpet rolled up) in the corners (where walls meet ceiling or floor) will help control bass frequencies.

Back to "attaching" wallboard. If building an actual interior wall is not an option and you must attach directly to the existing surface, Google something called Green Goo, which purports to be a sound-dampening adhesive you apply from a caulking gun. There are also special metal (somewhat springy) hangers made for this purpose. And there is a type of wallboard especially made for soundproofing: quietrock.com It comes in various grades, and sorry, none is cheap.

Here's some more background on the principles of sound control:

acoustics101.com

It's provided by a company that makes that sound-absorbing "egg crate" foam you mentioned. That stuff's not cheap either, and you don't need it for a home theater. Hanging some heavy drapes should do fine, if anything.

[Ted White]

As you stated, standard insulation is all that is needed. Higher density insulation is geat ON a wall, but not IN a wall.

Using clips and channels on a wall or ceiling is great decoupling, however they are designed for use directly on the stud or joist. These are not effectively deployed on existing drywall or plaster.

For in-room acoustics, non-parallel walls are seen. For pure soundproofing, the angled walls are not a factor.

[Sensible]

Agreed. So many people confuse soundproofing and sound conditioning or sound control. Two totally different things.

I was assuming that the hangars could be attached through the existing wall into the stud. But I've never used any of these products (am planning to), so don't go by me on that.

While I'm at it, I left out something -- the door. Use a solid-core door, suitably weatherstripped. In my studio, I even have two doors in the jam, with acoustic tile on one (facing the other), and the doors close against closed-cell foam. (Tip for novices -- the door should just barely compress the foam, or you won't get it closed!)

That leaves ventilation. The room of course needs it, but it's a great path for sound to travel, not to mention the sound the HVAC system itself makes. That's a whole other topic.

[Ted White]

I'd post a link to an image of s sound isolated soffit for ventilation, but I need 15 posts to include images / links, etc.

Anyway, the reason you can't use clips or channels on an existing drywall surface is because of the problematic air cavity that you are creating between the old drywall and the new drywall.

Your discussion of double doors is great. When closed, they create an airlock.

[mrcaptainbob]

sound control...

Great dialogue here. Am learning a lot. Thanks....

[Sensible]

When to use resilient channel, and when not

I've learned something, too. As you probably see in my reply to Ted White, I thought the problem in using Resilient Channels (springy metal strips between the studs and the drywall) was one of attachment. But the tutorial at Quietrock.com says that for the RC to work, it needs the depth of the wall cavity to work. I know any airspace is helpful, but apparently greater airspace is more helpful. And, now that I think about it, the channel would be resting fully against the old drywall, which probably transmits a lot more vibration to it as opposed to it contacting only the studs.

Quietrock.com states:

It should be noted that adding resilient channels to an existing wall (over the existing gypsum) will not increase STC values. There is not enough space between the old and new gypsum for RC to work effectively.

It's a long page about RC technology, claiming that the RC approach is fraught with opportunities to make mistakes that will negate virtually the whole effect. Overstated or not, RC does look like it takes a lot of care to do right.

There's also a section there specifically on home theater.

Of course, bear in mind that the company is selling its products, so who knows -- other solutions might serve well enough in a marginal situation.

When in doubt, do the numbers.

[Ted White]

Of course, bear in mind that the company is selling its products, so who knows -- other solutions might serve well enough in a marginal situation.

When in doubt, do the numbers.

Very sage advice.

The most common reason Resilient Channel is brought into litigation (quite common) is incorrect installation. The small air cavity per say isn't the problem, so much as there are two air cavities now. Both cavities resonating, and reinforcing each other. You only ever want one single air cavity. Better to remove the original drywall, then decouple to create only one air cavity.

[TransformStuff]

Sound is an invasive thing. The only way to get a really good job is to get very good insulation and design the room well for sound which sounds it is out of your possibility realm. There are tips like have been mentioned however, they won't truly nip it in the butt in my opinion.