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Best high R value wall for a music studio…

skidmorebay | Posted in Green Building Techniques on

Hello,
I am in the process of designing a small building that will be attached to the back of our house by a short breezeway. This will house my audio mastering business. I’ve hired an acoustician to help with the design.
Because of the close proximity to the house, he is specifying three layers of sheet rock for the inside, for soundproofing.

If I were to build a double-stud wall (per Lstiburek’s Ideal Double-Stud Wall Design), would this design create vapor-control issues in the wall? I assume that there would be no drying to the inside through three layers of sheetrock. (This is in Southeast Alaska – very cool and rainy year-round.)

Is there another high R-value design that may be better? The building will only be about 350 square feet. I want it to add minimal heating load to our house. It will probably be heated with one register from a ductless mini-split heat pump.
Thanks,
JS

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Replies

  1. DEnd2000 | | #1

    Yes and No. The extra mass will act as a larger sponge, so it will hold more vapor taking longer to dry out. However its moisture content percentage will likely stay about the same, it will just take longer to get "wet" and to "dry". Drywall itself is fairly vapor permeable, so it shouldn't create an issue.

  2. GBA Editor
    Martin Holladay | | #2

    Justin,
    With three layers of drywall, the wall will dry out just as well as a wall with one layer of drywall. But it's always a good idea to include a vented rainscreen gap between the sheathing and the siding with this type of wall.

    For more information, see How Risky Is Cold OSB Wall Sheathing?

  3. Expert Member
    Dana Dorsett | | #3

    +1 on the rainscreen recommendation, especially in that SE-AK location.

    Over the border in B.C. current code demands a 10mm minimum rainscreen for new construction, with lots of failed-building / dry-building data behind that requirement.

  4. exeric | | #4

    Three layers of drywall should definitely work. Usually in construction where there is a limit to the thickness of the stack up another technique is used. It's called constrained layer acoustic damping. This is where a layer of rubbery material is sandwiched between two layers, ideally different thicknesses, of drywall. This type of acoustic damping is very effective but can be very expensive in prepackaged constrained layer drywall. DIY versions are available that aren't as expensive. Try googling. Your system should work well. But it might be wise to combine these types if you are at all concerned of the effectiveness. It's a judgment call.

  5. charlie_sullivan | | #5

    A double-stud wall already reduces sound transmission significantly, so it might be overkill to also use three layers of drywall, but a see no harm in it.

    Just out of curiosity, is your main concern sound from outside getting into the studio, or vice versa?

  6. DEnd2000 | | #6

    The Rubbery material in Constrained layer acoustic damping is Mass Loaded Vinyl (MLV). MLV has a permeability of 0. Do not use it (or "quiet" sheet rock) on the interior of a double stud wall. It can be used on the exterior side of the interior wall's sheathing in the BSC double stud wall design.

    Charlie I can answer your question. Yes. Eliminating sound transmission both ways is important. From inside to out can easily disturb the neighbors, even home studio sound recording can get you in trouble with the neighbors. For example to get really distorted sounds from tube amplifiers they often have to be turned way up. From outside in can affect the quality of your recording, When my band was recording its album our mics picked up tweeting birds across the street, from inside the building we were in, and those were fairly cheap mics.

  7. skidmorebay | | #7

    Thanks for the replies, everyone.
    There will definitely be a rain screen.
    The goal is to keep sound from disturbing people in the house the building will be attached to.
    Am I right in assuming that a double stud wall is the most efficient way to high R-values? Stress skin panels aren't an option here. if there' s another method now is the time for me to decide which way I'm going with the design.
    thanks,
    JS

  8. charlie_sullivan | | #8

    What method is most cost effective to get a high R-value depends a lot of who your builder is, what their cost structure is, and what their comfort level and skill level are with different techniques. So if you haven't yet, it might be good to discuss with prospective builders. But for builders who are comfortable and proficient with it, it is a very cost effective way to get high-R walls.

  9. user-4053553 | | #9

    Would green glue help in this case since it dampens sound but it not entire wall covering like quietrock?

  10. exeric | | #10

    Alan,
    Green Glue was what I was thinking of when I mentioned googling for DIY constrained layer sound proofing. It seems to have good word of mouth, though there always seems to be outlier opinion that's negative. I chalk that up to the problems of catching all channels that sound can move through. If one is not expert on catching them all it may well seem like Green Glue is a weak link in the chain when it isn't.

    There's even opinion on musician and audiophile forums that it can be more effective than quiet rock. It's definitely easier to work with than quietrock as you can use standard techniques for installing both sheets of drywall in walls, except perhaps for the need for outlet extensions.

  11. Expert Member
    MALCOLM TAYLOR | | #11

    If you can use green Glue without it ending up on everything within a three block radius you are a better builder than me.

  12. user-4053553 | | #12

    My six sigma process will ensure it only makes it as far as two blocks at a 95% confidence interval :P

  13. Expert Member
    MALCOLM TAYLOR | | #13

    Judging by what ends up on my hands, truck seat and the wider universe, the top culprits are:
    1. Green Glue
    2. Roofing Goo
    2. Acoustical Sealant
    4. Subfloor Adhesive

  14. user-4053553 | | #14

    When mixed together i assume it makes the ideal all purpose goo?

  15. DEnd2000 | | #15

    Green Glue turns drywall from vapor open to vapor semi-permeable. http://www.greengluecompany.com/sites/default/files/GGNCompound.WaterVapor.DLLabs.20060106.pdf The reason for this is the airgap which changes the diffusion rates of water vapor (at least I think I'm understanding what is happening correctly) in the assembly. I would think this would add some risk to the wall.

    Ultimately how Green Glue works is by decoupling surfaces. In a double stud wall this has already been achieved for the most part. Yes the Green Glue will result in further decoupling and lower sound transmission levels, but sound levels are logarithmic, so the additional reduction won't be as perceptible. With a detached building in a suburban location using the BSC double stud wall design I'd bet Green Glue use isn't necessary. Paying attention to other details (such as window STC, air leakage, intake and exhaust ventilation duct routing and design) will likely provide more benefits.

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