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soundproofing room

Discussion in 'Recording' started by madrona, Nov 7, 2007.

  1. madrona

    madrona Guest

    We are in the process of soundproofing a room in an unfinished basement. The walls and ceiling have been insulated and we put on 2 layers of drywall with green glue inbetween. Next we plan to build a room inside this room. Now after reading Gervais' "Home Recording Studio" we realize that maybe we made a mistake in drywalling and should have followed his recommendation to have drywall, then insulation, then an air space, then insulation and then drywall again. Rather than taking down all our drywall, we are wondering if it would work to staple insulation to our drywalled room and then build our room inside. This would make our wall section look like the following going from outside the room (in the hall) to the inside:
    single drywall, insulation, double drywall with green glue, insulation stapled to drywall, air space, insulation, double drywall with green glue.
    Do you think this solution would work or is it not worth the effort?
  2. MadMax

    MadMax Well-Known Member

    If I am to take it that every one of the notations of insulation is actually a stud cavity.. then no, you will be defeating the existing wall mass and creating a triple leaf spring. With a triple leaf spring... might as well not even bother with the second wall... it will be just about useless expense.

    At this stage of the game, you pretty much only got two choices...
    1. Rip it down and start over.
    2. Add another layer of gypsum/Green Glue and live with what you get... forsaking the R-In-R design.

    Considering that you won't get any benefit from a R-in-R w/o your ceiling, my hunch is you'ld be better off rippin' it down (carefully) and starting over.

    Sorry for the bad news...

  3. Space

    Space Well-Known Member

    I'm reading like it's 3 sheets of rock on one side of a framed wall and 3 sheets of rock on the other side of the same framed wall.

    With the added block basement, that is currently 3 leaves if it is this way right?

    What keeps tripping me up is the stapling of the insulation to sheetrock. I'm not familiar with doing that.
  4. madrona

    madrona Guest

    Actually it is a basement with 1 side with concrete walls. The other walls border the hallway and bedrooms. The walls have a single layer of sheet rock on the hall side near the bedrooms and are insulated and then have a double layer of sheet rock with green glue on the other side of that wall which is inside the studio. We now plan to build a room inside this studio room by putting up another wall filled with insulation and a double layer of drywall with green glue. Our concern is the fact that we read that it is better to have two walls with the insulation facing each other rather than having the drywall facing towards the second wall's insulation. Sorry, I'm having such a hard time describing the situation! I have never heard of stapling insulation on to drywall either! I'm just trying to figure out the easiest fix.
  5. Space

    Space Well-Known Member

    The fellas that know this stuff will most likely, at this point, explain that mass is about all you can do from here. Installing more rock on the hall side and in the studio side of the same wall, can only help.

    In the beginning of this build ("...The walls and ceiling have been insulated and we put on 2 layers of drywall...") you have missed an opportunity to add mass to these outer perimeters. This is IF there was no sheetrock at all and all studs and joists were naked and visible to see.

    If they were not, then you haven't lost anything.
  6. MadMax

    MadMax Well-Known Member

    Let's try the old one layer at a time thingy...

    EXISTING Exterior to Interior
    1. Earth
    2. Unfinished Concrete (block) wall

    3. *Studio ROOM*

    4. Gypsum (thickness?)
    5. Green Glue
    6. Gypsum (thickness?)
    7. 2x4 stud Fiberglass filled cavity
    8. Gypsum (thickness?)

    9. *Hall*

    Is this correct?

    Pseudo Optimal (Room in a Room) Exterior to Interior
    1. Earth
    2. Unfinished Concrete (block) wall
    3. 1-2" airgap
    4. 2x6 stud Fiberglass filled cavity
    5. 3/4"MDF
    6. 5/8" Gypsum
    7. Green Glue
    8. 5/8" Gypsum

    9. *Studio ROOM*

    10. 5/8" Gypsum
    11. Green Glue
    12. 5/8" Gypsum
    13. 3/4" MDF
    14. 2x6 stud Fiberglass filled cavity

    15. 1-2" Airgap

    16. 2x4 stud Fiberglass filled cavity
    17. Gypsum (thickness?)

    18. *Hall*

    This might be overkill for your situation, or it might not be enough.

    The ceiling would need to attach/rest on the new 2x6 stud walls. (You could use 2x4's for the studs, but the more mass the better.) To make it structurally sound, the ceiling joists should be at least a 2x8 to handle the load of 3/4" MDF and two layers of 5/8" Gypsum w/Green Glue.

    Your floor is either going to need to be cut to provide gaps from the rest of the basement (flanking noise) or you should consider floating the floor inside the rooms. (Tracking and control room)... assuming you are building at least two rooms.

    I'm not a structural engineer, so PLEASE take part of what I'm telling you responsibly and get an engineer involved.... and be sure you get your permits and inspections, too!

    All the formalities out of the way
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