Dampening? or Isolating? Sounds in a pre-built room

There may be plenty of topics on this. I haven't gone past the first page, and am still doing ALOT of reading. Ive been googling as well (which is how I got here). I'm looking at purchasing my first home within the next few months. I'm no sense what-so-ever a carpenter, (my common sense pretty much ends at computer-troubleshooting, and a bit of financial management). I'm going to be renting out atleast one room to my younger brother. He and I both passionately enjoy music, however not always the same genre, nor at the same time. The houses im considering are single story, probably a 3 bedroom (assumingly all built parallel to eachother). He has a 450w 120w surround stereo sound system. In previous situations, we've literally had sound wars (who can go the loudest) as one of us tries to drown out the other. I'm greatly trying to avoid that scenario again. I'm trying to find a solution not to deafen his room, but make it "quieter" so that we both can enjoy our music at higher volume levels. My first thought was to use what I'm referring to (albeit probably incorrectly) as soundboards. What i'm actually talking about is the boards, covered in fabric, that I've seen used in auditoriums and church theaters). My idea was just to cover the walls with these boards, but having never done anything of this nature what-so-ever, I don't know if that will even begin to be adequate. I'd like to keep the budget "around" $500 at most, however, I understand that material is expensive, and would be willing to go to $1000 if need be. The room would start off empty, the size being 8x10 or 10x12. After whatever measures taken the room would accommodate a business-desk (4ft x 8ft), a twin size bed, a chest of drawers, and the stereo system. I'm currently reading: viewtopic.php?t=1589 http://www.homerecording.com/bbs/showth ... adid=88275 oh, and the "read this before posting" thread links to: profile.php?mode=editprofile, which I got a 404 on, but I was able to find the option @ ucp.php?i=164 EDIT: 02-13-09, corrected wattage on stereo system

Hi there, CJTE, and welcome! Do you want the good news first, or the bad news? :) OK, I'll try to do both at once, by answering some of your points directly:

He has a 450w surround sound system.

Ouch! Bad news! Assuming those are real RMS watts (and not fake "PMPO" watts), that's a lot of potential power. If he cranks that thing all the way up, you are definitely into triple digit decibels, which is not a simple matter to stop. Especially if he likes heavy thumping bass in his music.

I'm trying to find a solution not to deafen his room, but make it "quieter" so that we both can enjoy our music at higher volume levels.

Good news! It can be done. It is possible.

My first thought was to use what I'm referring to (albeit probably incorrectly) as soundboards. What i'm actually talking about is the boards, covered in fabric, that I've seen used in auditoriums and church theaters)

Bad news! That wont work. This is illogical and counter-intutive, but absorbing sound does not stop sound. As you point out in the title of your post, you already know that "damping" and "isolating" are two different things. In fact, they are pretty much opposite of each other. The materials you use to "damp" the sound inside a room are really lousy at "isolating", where "isolating" means to stop the sound getting out of the room (which is the same as stopping sound getting in). Conversely, the materials you use to isolate a room, are really lousy at damping it. The "soundboard" materials you are talking about, that you see in movie houses, theaters, churches, auditoriums, etc. that look like "carpet on wood" are not part of the room isolation: they are part of what you refer to as "damping", which is more correctly just called "acoustic treatment". The reason you can see those "soundboards" is because they are inside the room, where the sound is, and they are treating it! What you CAN'T see, is what is behind them, which is the isolation that stops sound getting in and out. You "damp" sound (acoustic treatment) with materials like that: thick fluffy things, like fiberglass, sheet rock, cotton batts, etc. But that does not STOP sound. There are only two ways to stop sound: One is with a vacuum ("In space, no-one can hear you scream"), and the other is with mass. In other words, very heavy, massive, dense things. "Fluffy stuff" is the exact wrong thing to stop sound. Concrete, bricks, drywall, thick glass, steel plate, lead plate... that kind of stuff will stop sound. But not carpet on paneling. To stop sound, you need mass, and lots of it. The louder the sound, the more mass you need.

My idea was just to cover the walls with these boards, but having never done anything of this nature what-so-ever, I don't know if that will even begin to be adequate.

Bad news! Nope, it wont. If you did that, then you would end up accomplishing two things: 1) The room would sound lousy, like a clunky dead cave. 2) You would annoy your brother with the level of sound still getting through to him.

I'd like to keep the budget "around" $500 at most, however, I understand that material is expensive, and would be willing to go to $1000 if need be.

Bad news. That may not be enough to do what you want to do. Especially if you have to hire someone to do it for you.

The room would start off empty, the size being 8x10 or 10x12. After whatever measures taken the room would accommodate a business-desk (4ft x 8ft), a twin size bed, a chest of drawers, and the stereo system.

"Starting off empty" is good news! Because in order to do what you want, you are going to need the room empty, as you will HAVE TO do some stuff that you probably will be horrified about, and you do it much easier with an empty room. And when you read the words, you are going to think something like "What!!!??!?! Are you NUTS??!?!? You want me to do WHAT?!!!?". Unfortunately, what I'm going to write here is NOT what you want to hear, but it IS the truth. It is the ONLY thing that will do what you want at a reasonable cost. The only other alternative is to build ten-inch thick concrete walls, and my guess is that you would be even less inclined to do that! OK, so here goes: With your empty room, rip off all four of the walls, and also the ceiling. . . . OK, are you still reading, or did you walk away? I hope you are still reading, because I'm still writing! What I mean is, you need to remove the drywall (also called sheetrock, plasterboard, gypsum board, and other things, depending on where you live) from the studs, on all four walls and the ceiling, and do it carefully, because you will have to re-use it, in order to save money (I guess you want to save money?). So don't attack it with a hammer! Cut it carefully with a drywall saw, at the edges of the studs, and save it. The reason you do that is because you need to get inside the wall, for two reasons. One is so that you can add more mass to it. The other is so that you can "decouple" the two sides of the wall. The reason why you end up in "sound war" battles with your brother is because of the studs: the sound from your stereo makes the drywall vibrate, which makes the studs vibrate, which makes the drywall on the other side of the wall vibrate, which makes the air vibrate, and of course "vibrating air" is what we call "sound". So to stop the sound going through the wall like that, you have to "decouple" the two sides, which means that you have to break the connection that the studs are making at present. OK, so you got to the point where you took the drywall off your side of the walls. Now, remove the insulation inside the walls, and you will be able to see the drywall on the other side of each wall. Take the pieces of drywall that you saved, and fit them back inside the walls, between the studs, up tight against the drywall on the other side. Hold it in place with cleats. Caulk all around the edges carefully, to get an airtight seal. this is called "beefing up" the wall. You are adding mass to it, so that it blocks sound better. Now put the insulation back inside the walls. If there was no insulation in there originally, then buy some mineral wool, and put that in. You must completely insulate the entire wall, thefull depth of the studs, floor to ceiling. Now buy some stuff called "resilient channel", which looks like long bent metal strips with holes or slots in the sides. Screw that across the studs, horizontally. The purpose of the resilient channel is to decouple the walls. DO NOT buy something called "hat channel" by mistake! It looks the same, it is cheaper, but it does not work. It MUST be true resilient channel. Now, buy some 5/8" drywall, and screw it to the resilient channel, but be careful that your screws ONLY go into the resilient channel ("RC" for short). THIS IS VERY IMPORTANT! You do NOT want any of your screws to go into a stud! Now caulk all around all of the edge, including down to the floor, and in between the joints. Once again, it must be air-tight. Tape and mud. Now buy some more 5/8" drywall, and also buy some stuff called "Green Glue" (which is not actually glue at all, but it is green). You are going to attach a second layer of drywall on top of the layer that you just put up, but you are going to put a layer of Green Glue in between the two layers of drywall. Green Glue ("GG") is a special acoustic treatment that helps a lot to "dampen" the walls. There is NO SUBSTITUTE!!! Do not be fooled. It is expensive, but there is nothing else that even comes close. Don't let any quick-talking salesman tell you otherwise. You also need a lot of it: About three tubes per panel of drywall. (You can do it with just two tubes per panel if cost as an issue, but it won't work as well. Your call.) Stagger the joints on the two layers of drywall, so that the second layer of drywall does not line up with the first. Caulk, tape, mud, sealed airtight, just like the first layer. Once again, when you are screwing the second layer to the first, by VERY careful that your screws only go into RC, not into studs! If you get even ONE screw that touches a stud, then you did all of this for nothing, because that screw will couple your wall again. And you went through all this torture to decouple it! So be very careful about that. Now do the same for the ceiling: RC across the joists, many inches of thick insulation above and between the joists, two layers of drywall screwed to the RC, with Green Glue in between, staggered joints, no screws touching joists, everything caulked up airtight, tape, mud, paint to taste. Do not cut holes in your new walls and ceiling for lights, cables, plugs, etc! Only use things you can mount on the surface, such as track lighting, surface-mounted cable ducts and plugs, etc. Any hole you make is a path for sound to get through. No holes. Or if you just HAVE to have a hole for something, then seal it extremely well with acoustic putty. Thick. Now replace your ordinary door with a thick, heavy solid-core door, and install the best quality, heaviest duty weather strip seals that you can find, all around the edges of the door. Use two sets of seals. And make sure you get them airtight. Now repeat all of the above steps in your brother's room. Of course, if his room is right next to yours, then you don't need to treat the wall that is in common between the two, since you already did that from the inside. But if he is two rooms over, then you need to do it. Both rooms must be isolated like this, all four walls, and the ceiling. Just doing the common wall in between you will not work, as sound will get around it, through the other walls and the ceiling. If you do it all correctly, then you have now finished your ISOLATION. Now you can start with your acoustic treatment, if you need it. The isolation I outlined above should give you an STC rating of about 55 or so for your walls and ceiling, rather less for your door (and we didn't even talk windows there!). That should be enough to keep you both happy. Unless, of course, you both have wooden floors in your rooms. I'm assuming that you both have concrete floors. It there are wooden floors, then you have a much bigger problem, and the solution to that is way outside of your budget. If you have wooden floors, above will still help, but there will be "flanking" through the floor, so it won't be anywhere near as good as if you had concrete floors. OK, I hope you are still reading! I'm sure the above is NOT what you wanted to hear, but unfortunately it IS the only way to do want you want on tight budget. Even then I don't think you can do it for US$ 500: Just the Green Glue alone will probably cost you that much. And since you say that your carpentry skills are probably not up to this kind of work, then you might need to hire someone to do it for you. Anyway, you did ask, so there it is. If you want decent isolation between the rooms, you need to treat BOTH of them like this. Then, when all of the above is done, if they sound lousy inside (they probably will), then you can think of what type of acoustic treatment you need to install. But that is a whole different ball game... I hope I didn't scare you too much! - Stuart -

Stuart: THANKYOU! I did keep reading :) Now its time for me to print that to hard copy, slowly buy the material, and then some day get to work!! Thankfully, I have a few months before I actually purchase (any) home, so that'll give me time to save, and talk with my friends (I know plenty of people in the construction business, but, One of the posts I read yesterday said that CONSTRUCTION experience means almost nothing when it comes to SOUND ISOLATION...) The only question that I have for now is, is a 'drywall saw' essentially a sawzall?

You are welcome! When the time comes, please do drop in again. My bet is that you'll have many questions around about then, and it would be much easier to help you if you can give us actual dimensions, existing construction materials, sound levels, etc. So when have bought the place and are about to get started, drop in again and post a diagram of what you have. I hope you noticed one thing I mentioned in there about floors: If you have normal wooden floors, all bets are off. If you have a choice, try to buy a place that has concrete floors. For starters, a place with wooden floors might not be able to take the extra load of all that sheetrock you need to add! We are talking several hundred kilograms, at least! (depending on room dimensions). Of you have a place with a good concrete slab poured on grade, then there is most likely no problem. It can take the weight. And it also gives you MUCH better isolation to start with. Sound travels through wood very well, so even if you build fantastic walls but have a lousy floor, the sound will still get there. Fixing wooden floors is much harder (and more expensive) than fixing your walls and ceiling. So if you can, get a place that has concrete slab floors.

One of the posts I read yesterday said that CONSTRUCTION experience means almost nothing when it comes to SOUND ISOLATION...

You certainly got that right! For builders who have never done a studio and have not be trained in the issues of acoustics, it all sounds very wacko. They'll ask things like "Why would you want to use CAULK inside a WALL?", with an expression on their face that makes you think they are about to bolt for the door and yell for the funny farm to come take you away... They probably need to un-learn a lot of what they "know" about sound and construction, then re-learn how to do it right.

The only question that I have for now is, is a 'drywall saw' essentially a sawzall?

I think so, but I'm not sure! I live in Chile, South America, so I'm not sure what names you guys give your tools where you live. But xSpace can certainly answer all your tool-and-construction-techniques questions. Good luck! - Stuart -

I did want to re-iterate that im not trying to completely (or anywhere near) silence the rooms, just lower the db level when greater than say, 10ft away. I've made a ground-breaking discovery as well. I was lied to, and in turn Ive errored in my post. The stereo is only 120 watts, RMS (60 x2). Im going to go fix that in my original post now...

The stereo is only 120 watts, RMS (60 x2).

Ahhhh! OK! That makes a difference in sound output, for sure, but not very much of a difference in isolation treatment. You still need decoupling (resilient channel) and you still need mass (sheetrock), so you still need to open up the walls and ceiling, which is the big job. You might be able to get something a bit thinner than 5/8 sheetrock, but it won't save you very much money. Probably not worth skimping on that. You MIGHT be able to live without Green Glue, which would save you quite a bit. It isn't cheap. Hmmmm .... What type of music does your brother play, and what part of it do you hear most? I'm guessing that what you hear is mostly low frequencies, such as thumping of the kick drum, bass guitar, etc. Or do you also hear the singers and electric guitars clearly, when he turns it up to maximum? - Stuart -

This is going to be where the trouble starts... I cant tell you what I will hear in the new house until... We get into the new house! He listens to "punk rock", or "new age rock", Hell I don't even know what it is anymore... Not a whole lot of bass, but there is plenty of electric guitar, most of the singers (literally) whine into the microphone about how bad their lives suck, etc etc. Its not emo though, and the kid doesn't dress Generation X "Goth"... He listens to a little irish rock too... I'll get band names if you'd like to hear demos, when I can. In previous houses, where our rooms have been parallel, I heard mostly acoustics (guitar, the lead singers voice drown in there somewhere, some drumming, but not heavy thumping bass). OH, and, I answered my own question, by the way... A drywall saw is a small hand tool made for cutting, you guessed it, Drywall! The sawzall (also referred to as a Reciprocating saw, because it moves the attached blade forwards, and then backwards, repeatedly), is a power tool with changeable blades depending on the material. My assumption is that there is more speed with a sawzall, but more care and attention to detail with a drywall saw.

From the sound of it (no pun intended!), you might just be in luck! Your average 120 watt stereo probably isn't able to put out too much energy in the low end anyway, and if what you are hearing most is howling guitars and singers, then that is pure mid range so the kind of construction I outlined above should do the trick. Thanks for the info on the tool names! You live and you learn! I'd suggest that while you are still house hunting, that you carry on reading some of the construction threads on this site. You'll find LOTS of useful tips and tricks and pitfalls and insight, that will serve you well when your turn comes. And you'll get a better understanding of the principles behind all this, the reason why you need to do what you are doing. Apart from that, this place is just so chock full of solid information on acoustic construction, it's just plain fun to read! I wonder if anybody has managed to read ALL of the threads? - Stuart -

You can also use a heavy mass to decouple the speakers from the floor. This would help with vibration that is generated directly from speakers to the floor. It isn't going to change the airborne sound concerns but it is something to consider. "CONSTRUCTION experience means almost nothing when it comes to SOUND ISOLATION" I have a saying I just made up, "studio construction is still construction, if you are not good at one you probable won't be good at the other." The difference that sets a professional construction rat apart from an auto mechanic is that studio construction is simply another aspect of the trade, still requiring all the day-to-day tools with much of the same materials. It is not a NEW thing to the rat. It IS a new thing to the mechanic or broker or waitress. This is why it looks all shiny and new:) New tools, fancy lingo, getting your hands dirty... To me, It looks like the difference between working on a bridge or working on a ten story mid rise condominium. It's still using specific materials in a specific way to do a specific job. You give a set of blue prints to someone who is used to working from them and they can get it built. Give those same prints to the auto mechanic or waitress and see where that ends up;)

I have a saying I just made up, "studio construction is still construction, if you are not good at one you probable won't be good at the other."

You mean kind of like the difference between a butcher and a surgeon? After all, they do the same basic thing: they just slice up meat! So a poor surgeon would be no good chopping steak either? Just like a poor studio builder would be no good at building ordinary houses? :) (Just kidding! Couldn't resist! Sorry! Totally off topic. Way past my bed time.... gotta get some shut-eye...) - Stuart -

Soundman2020 wrote:

If you have normal wooden floors, all bets are off. If you have a choice, try to buy a place that has concrete floors. For starters, a place with wooden floors might not be able to take the extra load of all that sheetrock you need to add! We are talking several hundred kilograms, at least! (depending on room dimensions). Of you have a place with a good concrete slab poured on grade, then there is most likely no problem. It can take the weight. And it also gives you MUCH better isolation to start with. Sound travels through wood very well, so even if you build fantastic walls but have a lousy floor, the sound will still get there. Fixing wooden floors is much harder (and more expensive) than fixing your walls and ceiling. So if you can, get a place that has concrete slab floors. -

What is a reasonable approach to isolating a the floor of room that has the dreaded normal wooden floors? Unfortunately, that's the situation I find myself in- my floor is: hardwood over plywood over wood subfloor over Joists. I have a bad case of slab envy right now. :?