Resilient Channel/Bar help please

Discussion in 'Builders' Talk' started by Damian Murray, Jan 4, 2019.

  1. Damian Murray

    Damian Murray New Member

    I am currently soundproofing an existing stud wall between en-suite bathroom and bedroom. Have filled cavity with Rockwool (as suggested on other threads) and am about to install resilient channels/bars.

    When installing do they have to be attached to vertical struts only? As you can see from this pic the channel at the top will need to be attached to a horizontal strut.

    Also due to pipework in the wall the lowest channel will need to be fixed to the horizontal strut at the bottom of the wall.

    Will this ‘undo’ the benefit of installing the channels?

    Also - I am using acoustic plasterboard (knauf blue back stuff) to fix to the channel(s) - what length screws should I use? I have 42mm but would prefer a slightly shorter screw if possible to ensure I definitely won't hit pipes (I have marked where they are but better to be safe than sorry...and wet [​IMG]).
     
  2. Wayners

    Wayners Screwfix Select

    Bars go across so will have to go wherever. You will need one top and bottom with 3 in the middle section. I would pack board at bottom to lift off floor and shoot some foam to hold. Sound don't travel through foam so board should not touch floor and small gap along ceiling filled with caulk. The idea is the boards sit on bars and they would bounce if floor and ceiling wasn't there to stop movement. Floating.. As for screws board plus metal is all you need so 17mm would be long enough as nothing after the thin metal to grab. So try 25mm and see if it works. That's how I would do it. Got one job coming up so please let us know how you get on
     
    Last edited: Jan 4, 2019
  3. Damian Murray

    Damian Murray New Member

    Thanks for the reply.

    Do you mean put board under (got some 5mm board knocking about) while fitting then remove after fitted? That is what I planned to do and then fill all gaps with acoustic sealant.
     
  4. Michaelsf90

    Michaelsf90 Member

    Resilient bars would be fixed horizontally. Make sure you fix the bar with the fixings at the bottom so the board will move away from the frame. The bars are usually no more than 150mm in from the top and the bottom and then can be installed at 600 centres on a wall. Like Wayners said make sure you don't screw into the studwork and leave no bigger than a 5mm gap around the edge but a gap is essential and fill it acoustic sealant. AC50 or AC95
     
  5. Michaelsf90

    Michaelsf90 Member

    25mm screws max
     
  6. Wayners

    Wayners Screwfix Select

    Yeah.. But it needs to be air tight so mastic or foam.. I like the foam idea
    Gun £10 B&Q.. Spray foam cleaner on the end as you go or it clogs. Use old mastic tube nozzle for a fine live of foam. Just shove on the end. Guns are controlled by trigger screw. That's my plan
     
  7. Michaelsf90

    Michaelsf90 Member

    It needs to be airtight but it needs to be a flexible sealant to help with the acoustic properties. If you use mastic it'll keep it air tight but I'd suggest using a sealant that is flexible as it'll improve acoustic performance
     
  8. Damian Murray

    Damian Murray New Member

    Thanks for all the advice.

    Bars are up. Took a little time as I needed to swear a bit and have a small argument with the other half about how long it is taking

    Sealed all around frame with AC95.

    Boards going up tomorrow. Likely with more swearing and another argument
     
  9. Damian Murray

    Damian Murray New Member

    Another question...

    Floor to ceiling is 2.4m. Plasterboard is 2.4m x 1.2.

    I was going to have joint running across centre (horizontal). However I cut I am going to need to remove a teeny tiny amount of board...what is the best way to do this?
     
  10. Wayners

    Wayners Screwfix Select

    Soundboard is hard. Saw it along with some wood as a guide or cut both sides and snap off.. If you cut with knife... Cut deep both sides for tiny amount to be removed so it snaps easy. Join need support to if you have one.. You can stick a strip of board on the back to fix both boards... Use no nails or fast set. I normally can't wait for it to dry so I use 2 pack wood filler as sets in 10mins to hold strip then no nails for next board that will fit on top of strip. Hope that makes sense. What I'm saying is.. 2 boards will have a strip of plasterboard stuck down the join at the back to firm up.. However if you are double boarding, this is not needed as top sheet can be fitted so join is in different place to first sheet, and I would run no nails at the back to hold join
     
    Last edited: Jan 5, 2019
  11. Wayners

    Wayners Screwfix Select

    Do you need self taping (drill on the end) screws for these resilient bars? I guess so and can they be bought from screwfix?
     
  12. Michaelsf90

    Michaelsf90 Member

    Drywall screws. Just make sure they aren't too long. You don't want to go through the resilient bar and into the timber/wall or it defeats the point of using resilient bar. What thickness is the plasterboard. I'm using 15mm so I've got 25mm drywalls for the first board and 40mm for the second layer of board
     
  13. Wayners

    Wayners Screwfix Select

    @Michaelsf90 I'm going to put up timber to existing wall then stuff full of acoustic rockwall then resilient bars at 5 going horizontal top to bottom. Keep a small gap all the way around and fill with acoustic sealant then 2 sheets of the blue plasterboard staggered joins. My question was regarding how easy it is for screws to get through plasterboard and metal bars? No pilot hole needed then? I have 25 32 and 38mm drywall screws here...thanks
     
  14. Michaelsf90

    Michaelsf90 Member

    No pilot drill needed at all. Drywalls have a very sharp point on the end. If your using a drill and screwdriver bit then you need a ph2 bit not a pz2. The screws will countersink into the board just make sure not to sink them too deep. Very intrigued how you get on as I'm soundproofing a party wall myself. Sick of hearing the neighbours talking even with the tv on at times. When theirs quiet parts. Infuriating. What rockwool have you used?
     
  15. Wayners

    Wayners Screwfix Select

    Not got wool yet but B&Q have it for £48 a pack. Sound acoustic slab stuff. Resilient bars i bought local 3m long. One of the Travis group . Ccf limited.. Look them up ....
     
  16. Michaelsf90

    Michaelsf90 Member

    I've found rockwool a lot cheaper online but it's delivery. Wickes do acoustic rockwool for £28. Dont know the thickness. I was looking for 50mm rwa45. It's 45kgm3. They do different types with higher kgm3 but it's a lot more expensive. I found the rwa45 for £21 a pack but delivery was £45!
     
  17. Damian Murray

    Damian Murray New Member

    My wall is up and plastered. I used Drywall screws - all were OK for getting into the bars. Because some were a little close to the studs (so I couldn't be 100% that they were not touching) so I drilled to get the hole in the bar and then clipped the end off the screw before screwing it back in.
    Yep - rockwool is much cheaper online but when you add in the cost of delivery you may as well just goto Wickes and buy it (unless you are doing a very large area).
    I ended up double boarding but for the second board I used 15mm soundboard - figured it was not much more cost and I wasn't fussed about losing a little more of the room. Did it make THAT much difference? Personally I don't think so but if I had not done it I would have always wondered.

    I suppose the question is has it been worth the effort? I think so. There is certainly a drop in the noise between the 2 rooms - I think it would have been nearly impossible to get rid of all noise (for example if the shower is run you can hear the water hitting the tray) but it was worth it.
     
  18. Michaelsf90

    Michaelsf90 Member

    Did you do all the work yourself? I think it will help it's just what your expectations are. I'm not expecting to not here anything but I'm expecting it to be muffled and not clear. I just want to be able to watch tv in peace. Or get nicer neighbours
     
  19. Damian Murray

    Damian Murray New Member

    Yep - did it all myself and didn't screw into a single water pipe! Might have drilled into the cable going to the upstairs light circuit on the opposite side of the room but lets not talk about that!
    Mutltitool was a godsend for trimming the plasterboard where I needed to take off small amounts due to floors/ceilings not being dead straight.
     
  20. Michaelsf90

    Michaelsf90 Member

    Be bad if a qualified electrician drills through a cable while he's doing it. The joys of DIY. What insulation did you use? I'm still working out how to get the plasterboard lifted off the floor to leave the gap around the edge with the weight of it
     

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