Sound reduction with a slight twist

Discussion in 'Home Cinema Building DIY' started by Goof, Mar 29, 2016.

  1. Goof

    Goof
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    I'm currently renovating and about to start on the living room, which is adjacent to my son's bedroom (both rooms in the corner of the house). My plans make things tricky but I'd like to make reductions where possible (I've attached a diagram to help illustrate).

    noiseyrooms.jpg

    At the moment the stud wall in question (between room 1 & 2) is tiled, I had intended just to dot & dab another layer of soundbloc over the tiles (as attempts to pull other tiles away bring the plasterboard with them). The question is whether leaving the tiles would help or hinder sound reduction? The M-S-M theory of reduction would suggest it's ok (extra mass?) but not sure whether resonance etc would actually mean it's more of a transmission bridge.

    I can't afford the space to create another stud wall but I'd seen acoustic matting on ebay - does anyone have experience with this? Once complete I gather it's best to avoid screwing or fixing anything to the wall? (which would mean relocating a radiator, which isn't ideal).
    I was planning the same sound reduction between walls #2 and #3 - I'd like to wall mount the TV (so would have TV's on either side), but again the no fixings thing a bit of a sticking point. I'll also need to bring cabling through and get power points, so it's really a question of whether compromising the soundbloc'd wall makes the whole operation pointless? One side of that stud is still exposed - the joiner had filled it with Kingspan, however, reading suggests dense rockwool is a better option for noise reduction, so it sounds like I'd be better pulling that out?

    The final complication (that may make all other points moot) is the doors between 1 & 2 are only about 1.5m apart. We need to bring more light into the hallway, so I'm planning on putting french doors in #2, so we've got another (possibly worse) sound transmission problem there. Standard hardwood internal doors come with toughened glass, but I'm wondering if buying frames separately and fitting double-glazed panels would be advisable.

    I realise there's quite a few points there, so any thoughts/suggestions welcome!
     
  2. Plasma Dan

    Plasma Dan
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    How about if you open-up one side of the wall, and build another with offset studs. This would only add a small amount of depth to the wall, but will offer decoupling between the two rooms. :smashin:

    [​IMG]

    You can then apply soundbloc boards etc to add mass, and since you would have access you can also install acoustic insulation (rockwool). :smashin:

    Seems you've already answered your own question. :rolleyes: Adding extra mass is good yes, but the tiles may create a problem. Plus if you plan to dot & dab, that would create another cavity. See here on "Triple Leaf Effect".

    There are no short-cuts with soundproofing (unfortunately). :censored:

    You can fix whatever you like provided you account for it, so avoid leaving holes etc. As for electrical there are ways around it without compromising on soundproofing. I have a lot of sockets etc on my build (see here), I found a good way to maintain the integrity of the soundproofing was to mount the back-boxes onto an MDF panel, and seal them using acoustic sealant. This way the box is only attached to the plasterboard to keep it detached from the wall (or in your case studs). Since you will have more space in a partition wall you could double-up on the MDF also. :smashin:

    [​IMG]

    Anywhere where you intend to attach something like a TV, all you need to do is install extra studs into the wall where it will be. You can just use a piece of 18mm plywood or something similar, and mount it flush with the studs.

    Rockwool is better, but only marginally. If you have access it may be worth doing since rockwool is not expensive.

    Double-gazing would certainly help, but generally it's best to avoid glass panel doors if possible. I did look into using high density clear acrylic windows for my doors, but decided against it due to cost.

    Dan.
     
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    Last edited: Mar 29, 2016
  3. Goof

    Goof
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    Thanks for the detailed info Dan - work's been set back so not had much of a chance to look into this further.

    One other thing I'm pondering, I was considering green gluing 2 layers of soundbloc together on the TV party wall - just wondering if it'd be better to put a layer of acoustic matting between them? There's stuff on eBay that's only a few mm thick and almost as cheap as green glue!
     
  4. Nayfne

    Nayfne
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    Sorry to jump in on the thread.. but a quick question to @Plasma Dan..hve you insulated around any double plug sockets and electrical cable using rockwool? As in cut the rockwool around the sockets and cables? Is it ok to do this? TIA[emoji106]
     
  5. Plasma Dan

    Plasma Dan
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    Insulating around plug sockets is fine, however cables buried in thermally insulating walls should be derated to prevent overheating of the conductors. The rules regarding this change quite often so it can be difficult to find the correct information online, but generally speaking provided you know the cable is oversized for the fuse / circuit breaker you should be fine.

    For reference here is the official word (taken from BS 7671:2008+A3:2015 ON-SITE GUIDE):

    2017-03-27 20.00.39.jpg

    2017-03-27 20.39.43.jpg

    2017-03-27 20.41.21.jpg

    2017-03-27 20.01.09.jpg

    Hope that helps. I recommend acquiring a copy of the on-site guide. If you're ever unsure about anything it will be in there. :smashin:

    Dan.
     
    Last edited: Mar 27, 2017
  6. Nayfne

    Nayfne
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    So if I cut a channel in the rockwool so there is clearance/channel for the cable to freely move/sit in and not buried? Sorry for the novice questions mate.
     
  7. Plasma Dan

    Plasma Dan
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    Avoid covering the cable completely with insulation and you should be fine. As-long as the cable is touching the plasterboard on one side a 2.5mm^2 cable should be fine for either a 16A radial circuit or a 32A ring final circuit, obviously not taking any other derating factors into account.

    Dan.
     
  8. Nayfne

    Nayfne
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    Thankyou dan..its a partition wall adjoining another bedroom, so have only taken one side of the old pb board off and will be filling with rockwool then Soundbloc pb, so definitely not burying any cables..the only cable on the wall is for the double plug socket, so will be sitting in front of the rockwool and onto the new PB...sorry to the original post for going off topic..[emoji106]
     
  9. Goof

    Goof
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    No problem Nayfne.

    I still haven't got this job done (though took down tiled plasterboard and filled cavity with rwa45.
    Would still be interested on any comments regarding using the acoustic matting instead of greenglue though?
     

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