Soundproofing with decoupled ceilings (or isolating clips)

Discussion in 'Building' started by Yannis.sp, 24 Jan 2019.

  1. Yannis.sp

    Yannis.sp

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    Dear friends.
    I need to soundproof my ceilings because of laminate flooring upstairs, unreasonable neighbours who don't want to know anything about it, and excitable young kids.

    Hellish impact noise coming through.

    The plan is :
    •100mm acoustic rockwool slab between original joists.
    •New C24 timber frame(63mm×97mm timber according to http://nhbccampaigns.co.uk/landingpages/techzone/previous_versions/2010/Part6/section4/appendix.htm for a dead load of 36kg/M2 bolted on the masonry load bearing walls and insulated for flanking noise.
    •10-15 mm air gap
    •100mm acoustic rockwool again between new frame joists.
    •2 sheets of 15mm acoustic plasterboard with a 5kg/M2 viscoelastic or similar sandwich between the two sheets of plasterboard.
    •tape and skim

    I have some questions I hope you can help.

    1.Should I go as far as building a new frame for decoupling (as all research showed decoupling is the "golden standard" of soundproofing) or should I use genie clips with resilient furring channel to save the built of a frame and save head height.
    2.If I do build the frame is the timber sizing an overkill? I have not made it clear of these span tables are intended for floor joists meant to be walked on, in which case I can reduce the timber sizing and save room height.( Current setup will drop overall height floor to ceiling at 2300mm which I can live with)
    •Is the best way to hang the new joist steel brackets, or make a box around the square of the room and cross-screw the joists to it?

    Room size is about 2400mm×3200mm
     

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  2. endecotp

    endecotp

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    This may be difficult to fix as the noise will be transmitted into the walls at the ends of the joists.

    As you already have the ceiling down, get some acoustic insulation batts and fit them now, and see if it makes much difference.

    I suspect that timber will be cheaper than e.g. genie clips, so it is a win-win. The timber only needs to be strong enough to hold the weight of the ceiling plasterboard. How much room height are you prepared to lose? You can put the new joists between the old ones, maybe coming 20-30mm below, and thread a layer of insulation between the bottom of the old joists and over the top of the new ones.

    Consider leaving a 5mm gap between the plasterboard and the walls and filling with acoustic sealant.

    I believe you can get acoustic joist hangers.
     
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  4. StephenStephen

    StephenStephen

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    I've gone for the approach of having separate joists for the ceiling, with 50mm of cozy wool threaded between the two sets of joists, and i've been surprised how well it works, both with structural and airborn noise.
     
  5. Michaelsf90

    Michaelsf90

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    Have you checked out resilient bar? Also you'd be better using one sheet of 15mm soundbloc and one sheet of 12.5mm soundbloc as different densities help break up the sound waves
     
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  7. Ricardo Da Silva

    Ricardo Da Silva

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    I have almost the identical issue as you and spent many months mulling this over. The problem is that there is sooo much contradictory advice even from people claiming to be experts or solutions that are perfect for recording studios when all we need to know is; "Will it stop me hearing them stomping around up there and their bloody washing machine spinning all day everyday !"

    I finally opted to experiment below a bedroom with: inter joist 100mm RW45 + GenieClip + 10mm SBx + 15mm Soundbloc and the result is not bad. Can no longer hear any form of conversation, stomping has been practically eliminated and load impact has been reduced to dull thud. So it makes it more livable. However this room is not a high traffic area and so I am a bit reluctant to do the same beneath hall way, kitchen and living room.

    Was wondering how your build-up has fared and wondering if any one could advise whether upgrading my current solution to 100mm RW45 + Genie Clips + 15mm Sbx + Green Glue + 19mm Knauf Plank + Plaster Skim would make a significant improvement.
     
  8. DIYnot Local

    DIYnot Local

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