Resilient channel types

Discussion in 'Home Theater Projects' started by Bobby C, Jan 12, 2004.

  1. Bobby C

    Bobby C Stunt Coordinator

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    Hi,

    As I continue to work on my room (starting to frame), I'm beginning to investigate resilient channel. I've seen mention that there are different types - I went to my local HD & found one shaped like a hat (ignore the dots):
    ......___
    ...../....
    ..../......
    __/........___

    Are there other types? If so, what are the different qualities, what is preferred? If others are preferred, do people know of sources? Once I know the 'preferred' type, I can certainly do a web search & probably find it.

    Thanks!
    Bob
     
  2. richard_v

    richard_v Stunt Coordinator

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    I believe the "hat" shape is generally used for ceilings. For better isolation, I bought ones shaped like:
    .... - - -
    ..../.....
    .../
    --/

    I used then on the walls and ceiling with no problems.

    Rich
     
  3. Bobby C

    Bobby C Stunt Coordinator

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    Hey Rich,

    Interesting - where did you find this stuff?

    Thanks,
    Bob
     
  4. Tom Kay

    Tom Kay Stunt Coordinator

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    Hi Bobby

    At least in Canada, Home Depot also supplies the non-hat shaped metal channel, as well as the hat-channel. It's RC-1, I think, but basically it has a flange that gets screwed into the studs or joists, then the rest of the channel sort of "hangs" above the stud without touching it. There is a wider flange that you screw the drywall into. You have to be careful not to screw through the drywall, through the metal channel, and into the wood stud thereby creating a path for vibration to get into the wood, something you wanted to avoid in the first place. It's like grounding by mistake.

    I was surprised at how easily the drywall screws pierced the metal channel, as I expected to push all day with the screw driver and just keep spinning. But fortunately I was wrong, it works well. Use short (1") fine-thread drywall screws for going through the drywall and into the channel. you don't have to pre-drill or anything. Make sure the resilient channels are all oriented the same way, (all flanges pointing up) so they don't "cancel each other out".

    I did a small test panel just to see how it went. Piece of cake. When you're done, the wall should actually be springy, or float above the studs with a slight amount of movement back and forth when you push on the wall.

    The channels themselves are 12 foot lengths, and a couple dollars per piece. Good luck !

    Tom.
     
  5. Bobby C

    Bobby C Stunt Coordinator

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    Thanks for the info, Tom, I was wondering how difficult it would be to install drywall on the channel. My local HD doesn't have that type of channel, I have a couple of other HDs w/in 30 miles, I'll shop around. Did you use the same channel in the ceiling?

    Bob
     
  6. Tom Kay

    Tom Kay Stunt Coordinator

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    Hi Bobby;

    Here's the statement that will give you oodles of confidence: I haven't actually done my drywall yet !

    So, how do you like me now? Actually, I did my test panel, and that was enough to convince me that this will be easier than I thought. I will do walls first, then ceiling, partly because I'll still be pulling cables through for ceiling lights, after the walls are done, and partly because I'm still fixing hardwood floor squeaks, from below.

    At least I'll be able to sit in my HT and watch a movie, as long as I don't look up.

    I have been curious how to form strong bonds where sheets of drywall meet, and i think I'll use 1/4" wood screwed behind each seam, much like a joist or a stud being in place. This thin wood, would not touch anthing behind it, and I think it would help keep taped drywall joints from cracking. I'll pass along my experience as I acquire it.

    I also plan to keep the ceiling drywall about a quarter inch away from wall drywall, and fill with acoustic caulking, so that each wall or ceiling surface really can move and shift as needed. I'm really trying to observe all the principles of soundproofing. Again, we'll see ! Cheers, Tom.
     
  7. Tom Kay

    Tom Kay Stunt Coordinator

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    And of course, I forgot to focus on what you asked me.

    YES, I will use the resilient channel in the ceiling, ESPECIALLY on the ceiling, because my bedrooms are right above the theater.

    I work at an Aerospace Research facility in Ottawa Canada, and I'm quite happy about that. We're government, and the good thing is that there are several different areas (Institutes) of research around my campus. One of my faves is IRC, The Institute for Research in Construction, and they were good enough to send me an artical on soundproofing your basement. It dealt extensively with resilient channel, the best type of absorbent material inside the joist cavity, how many drywall layers to hang from the R/C etc. And then it gave decibel attenuation values for each scenario. (I also called the Roxul company who had their own specs on sound loss through various types of walls). If you have 5 inches of fiberglass insulation (Roxul is even better because it's denser, more absorbent, made from slag and rock) and one layer of 5/8" drywall mounted on R/C, this will kill around 48 db of sound. There's less effect for the lower frequencies, unfortunately. If you use 2 layers of 5/8" drywall, it's around 50 to 52 db attenuation. So I think I'll start with one layer and see how it works. The R/C acts is a disjoint, or disconnect for the sound, and that's why it's so flimsy between the two flanges. If you use the hat section, I think you are defeating the whole purpose (or most of it) of creating the disconnect between wall and inner framework.

    So, how's that for a guy who's not actually done this yet? Bottom line is that I am convinced that it'll work, but you must be anal-retentive about not screwing into wall studs, filling gaps with acoustic caulking and using a good door for the theater. If air can get out, so can sound. I am even cutting my 5" diameter heat ducts, and sewing a soft tube made of artificial leather, then clamping the soft tube back onto the metal ducting in place of sections I've cut out. Why? To keep sound from bouncing easily along the inside of the duct, back to the rest of the house. I think it'll work well, as I also have designed in 2-90 degree bends in each duct. I really want to see if this can work, and not keep my family awake while I'm in the sweet spot.

    So, my fingers are tired, but ask more if you wish, cheers, Tom.
     
  8. Bobby C

    Bobby C Stunt Coordinator

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    Well it will be a fun ride (building the HT) if nothing else! I'm petty much going to follow the same route as you, RC, 5/8" drywall, insulation between joists. I'm not sure what insulation I'm going to use (I'll be using a Kraft faced R-13 on my walls, may do the same in the ceiling). My local HD has some acoustic insulation (I'll check to see how much better it is than regular), but it's not Kraft backed, meaning it will be more difficult to install. If I used 'raw' insulation, I'll have to hold it in place w/ something (maybe chicken wire), that adds more time.

    One of the guys here (Erik) has used a layer of rolled roofing asphalt for an additional sound barrier. I may give that a try as well.

    Right now I'm studding out the walls, then wiring so I'm a bit away from it. But insulation, wiring, drywall, RC - these are the things that keep me awake at night (and keep me from working in the day)!
     
  9. Tom Kay

    Tom Kay Stunt Coordinator

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    Hi Bobby

    Speaking of keeping me from my day job, Hey, I'm a government employee, and I work in research, so I'm only too happy to help others with their research. Of course, I'd use a different story if I were questioned by management!

    So, I talked to Erik too, a while back, and I was very curious about how fire resistant or fireproof this roofing felt might be. I think he said it looked like shingles, and I remember as a kid (All young boys are closet pyros) burning some shingles, and they took a while to get going, but really burned like hell once they were lit. They sort of melted and dripped oily little globs of stuff, that stuck like napalm to whatever it touched.

    Something about this memory made me not use the roofing felt, even though I never absolutely confirmed it was just rolled up shingles. Be cautious though, about fire concerns. I like the Roxul product because It's made of slag and rocks, and has an enormous fire rating. It handles twice the temperature of fiberglass, plus it is not harmed by water, plus it's denser and absorbs sound better. Sounds like a good choice.

    Well, gotta go serve Queen and country. Cheers, Tom.
     
  10. Bobby C

    Bobby C Stunt Coordinator

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    Ah, yes, fond memories from childhood. We actually used shingles & plastic bags, we called them 'zerts' because that was the sound that the burning material made when a new glob of burning mayhem dropped to the ground.[​IMG] .

    I just emailed Roxul for information on where to obtain it, not sure we can get it here. How heavy is the stuff? And I see several different product lines, which one are you going to use?
     
  11. Tom Kay

    Tom Kay Stunt Coordinator

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    Hi Bobby

    Zerts. Ya, I think I can recall a sound to the burning globs dropping through the air.

    Roxul makes a few different products. Safe n Sound is actually denser by 25 % than their regular batt. But, it's only around 3.5 inches thick, so I had kind of figured on using Roxul Flexibatt, which is around 5.5 inches thick. Or, if I discover a money tree, I could use 2 layers of Safe n Sound, getting lots of thickness, plus the densest material I can use. I'll scratch my head and come up with a plan. Either way, I think they're pretty close.

    Tom.
     
  12. Bobby C

    Bobby C Stunt Coordinator

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    I contacted Roxul, they do not sell their products for residental use in the US at this time. I'll keep my eyes open for something similar.
    Thanks!
    Bob
     

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