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Plasterboard TV Mounting advice needed please

Discussion in 'Audio Visual' started by shishir, 15 Jul 2021.

  1. shishir

    shishir

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    Hello,

    I have a dot and dab wall where the plasterboard is quite thick, I believe it is double plastered? The gap from the surface of the plasterboard (facing the inside of the room) to the brick wall is 70mm.

    I want to mount a 55" TV ideally on a cantilever bracket. I have looked at many options and even had someone come in to give a quote on the job.

    Option 1 - Use hollow anchors- I have been advised this will not hold because of the weight of the cantilever anchor and the TV which is about 18kgs in total. In addition, I would need longer anchors than normal for the plasterboard depth.

    Option 2 - Corefix screws, the ones with the steel sheath around it. Unfortunately, even with the longest screws they have, the steel sheath will not breach the brick wall, I was banking on this option.

    Option 3 - Scrap the cantilever and just use a standard bracket. Please can someone confirm that using hollow wall anchors here would do the job?

    Option 4 - The guy that came to have a look today suggested something about drilling a hole into the wall, pouring some chemical resin in and then put threaded rods into it so it effectively bridges the gap and sits tight in the wall. At that point, I can then fix the TV on. Unfortunately, the quote was about £500 which is too much for me! Is this something an average person can do?


    Is there any other option that would suit my situation better?

    Thank you so much in advance!
     
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  3. motorbiking

    motorbiking

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    1. chop a chunk of the plasterboard out carefully with a floor board saw or similar. Keep that bit for later.
    2. Insert some stud/CLS timber noggins horizontally screw to the verticals and use a few frame fixer to attach it to the brick if necessary.
    3. Put the "panel" you cut earlier back in place with screws and fill the saw gap with plaster/filler and sand if necessary.
    4. Use wood screws to attache the bracket to the noggin which will be attached to the brick using a frame fixer.

    but I also like Option 4., but you could probably do it with frame fixers these 160mm will give you 90mm in the brick, but it depends on the brick wall i.e. bricks of breeze block. You could get away with shorter.
    https://www.toolstation.com/fischer-srs-frame-fixing/p58887
     
  4. shishir

    shishir

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    Thanks for the reply motorbiking.
    I'm a bit of a novice when it comes to this, so please can I clarify a few things?

    For your point 2., what do you mean by horizontally screw to the verticals? Do you mean vertical wooden beams behind the wall? If so, I don't have these as it is a dot and dab wall. In this case, could I just attach a number of wooden beams to the brick wall using screws (frame fixers)?

    For your explanation on Option 4, will normal 160mm fixers do the trick even if there is a void between the plasterboard and brick wall? I was given the impression that if the screw wasn't flush against the wall it might not be secure.
     
  5. motorbiking

    motorbiking

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    Sorry I was thinking an internal wall. CLS timber comes finished in 63mm so it should fit nicely in your 70mm void. You may even need to pack it with some ply. You need to cut a hole big enough to allow you to insert the horizontal noggins. Use a nail to stop them falling down inside. I'd go with two. Then wood drill and masonry drill to attach the noggins to the block using a few frame fixers. Then you have a solid wooden beam to screw your tv bracket to.
     
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  6. Sureitsoff?

    Sureitsoff?

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    the trouble with a cantilever bracket on a dot and dab wall is that the force exerted by the bracket can crush the plasterboard. if you think about it the top of the bracket is trying to come away from the wall and the bottom is being pushed in to the wall with quite a force so the suggestion above to try and get some decent timber in the wall is good. by putting the timber in to the wall you are effectively making the wall solid rather than having hollows where the dabs of plaster that hold the plasterboard to wall are missing . if the wall has been double boarded then two sheets of board will be about 25mm thick which means you will need to fill the void with about 45mm thick timber. think of it as trying to create a frame fixed to wall the same size as the bracket so that that part of the wall is solid without a void behind.
     
  7. JohnD

    JohnD

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    what does your bracket look like?

    Mine has a flat steel plate with lots of screw holes in it. I positioned it so that a few screws went into a stud, thus supporting it, and the other screws, into plasterboard, mostly prevented it wobbling about. The studs are probably 14" to 24" apart, so unless you have a very big plate, or find a noggin, you will only be able to screw into one.

    edit
    oops, sorry, I see your wall is d&d, not studwork.
     
  8. shishir

    shishir

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    Yeah I agree Sureitsoff, especially when the bracket is extended out, it exerts too much pressure.

    Its looking like filling the void with timber is the best option, my only concern is about sawing the plasterboard wall is that I haven't done that before but I'm sure I can find some guides on youtube. The resin idea seemed great, but if the rods will be strong enough as it will still be resin-free and outside of the brick in the hollow part.

    John, problem is its dot and dab wall, so theres no studs at all. I'm still thinking simple wall anchors might work if I put on about 8 of them on the bracket, but a normal bracket, not a cantilever one.
     
  9. winston1

    winston1

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    No doubt you only want to see the TV on the wall. Consider how you will need a power point, aerial point, satellite point, HDMI, and ethernet points behind the TV.
     
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  11. Sureitsoff?

    Sureitsoff?

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    When you do saw through the plasterboard to get some timbers fixed to the wall you might find that the adhesive that is used to stick the plasterboard to the wall a. means you have to destroy the section of plasterboard just to get it out and b. the dabs of ahhesive will be absolutely rock hard like concrete so will be very difficult to get off the brick to then give you a flat surface for the timber. And as winston says above what about power and signal cabling. To go back to your suggestion of using threaded rod into chemical anchors (resin) it should be possible especially if you can put a nut on the rod and have the nut set flush with the level of the plasterboard. The only thing I would be worried about would be the rod might bend slightly unless it was 8 or 10mm thick.

    If you use a flat bracket rather than a cantilever one then there is a LOT less force exerted on the wall so simple plasterboard fixings would do IF you are lucky and find the void for most anchors to open up into. Or you might be very lucky and be able to use the concrete like dab of adhesive to just use a wall plug and screw !

    wall anchors on test !!
     
    Last edited: 15 Jul 2021
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  12. rsgaz

    rsgaz

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    That's HUGE!! So, 70mm, minus two sheets of plasterboard equals 44mm(near as dang it), which is a very common size for planed timber. :whistle::whistle:
    How sure are you it's dot n dab and not studs/battens? 44mm adhesive dots is just ridiculous. Imagine how thick it would have needed to be slopped onto the wall before the board is dabbed on?

    If it really is dot n dab, then as John says, just get a big bracket(non cantilever) with loads of holes, and several of your fixings will line up with adhesive dots and then the plasterboard can't crush. Therefore, 50mm by 10mm nylon plugs hammered all the way through into the brick (Fischer ideally), with 120mm M8 coach screws and jobs a good 'un.

    Gaz
     
    Last edited: 15 Jul 2021
  13. JohnD

    JohnD

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    I like that idea. A big square panel, slightly smaller than the TV so you won't see the join while you get round to redecorating. If you cut the panel first, you can draw round it on the wall for your cut line.

    A half moon blade in a multicutter will do a neat cut.

    Put a rough square wooden frame inside that you can fix your old plasterboard, and your new hatch, to. Pack the brick wall near the screw holes to level it against the plasterboard (expanding foam might possibly do). Poke your power cable, aerial cable and LAN cable (screened) down (it will give you a better signal than wifi) and fix backboxes. Screw the bracket into the wooden frame

    Lovely job.
     
  14. motorbiking

    motorbiking

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    As well as toslink abs hdmi etc.
     
  15. Lucid

    Lucid

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    This probably explains a lot.

    Your identification of the wall construction is questionable. The reason is that the numbers don't add up. Someone else has mentioned this too.

    The board adhesive would have to be laid on so thick that it would probably run down the wall under its own weight before the board could be placed. That sort of adhesive volume would also make it difficult to level the board. Either the wall construction isn't dot-n-dab or the builder/plaster employed was a complete monkey. I can't rule out either, but I'm leaning towards the former as a possible answer.

    We can help with advice, but the person asking for help also needs to have some basic DIY skills to start with.

    Hanging a £500+ TV safely off a movable cantilever bracket isn't the sort of task for someone to attempt who hasn't much of an idea of one end of a drill from the other. Not only do you have to factor in doing the job (and whether you've even got the right tools for it), but you also need to be 100% sure that your handy-work will stand up to (a) time and (b) other people moving/using the gear who would presume that it was mounted competently. They're not going to know to treat it with kid-gloves because it was put up by someone with only half an idea how to do the job right. Either skill up, or get someone on-site who knows what they're doing.

    There are a couple of reasons why you were quoted £500. Being cynical, you could say that the tradesperson was trying to lift your leg on the price of the job. On the other hand, maybe there's more to the job than you're describing here and the tradesperson knows what they're doing and what will be involved to do the whole job, not just hanging the bracket for the TV. @winston1 is correct; you haven't mentioned anything about cabling so far. All you've talked about is the physical bracket mounting.

    In all honesty, with the studs and resin solution that's perhaps a 3-4 hour job including sheeting up and then cleaning after. It's a morning or afternoon's work. The real work is in getting the cables to the TV, and power too, and possibly dealing with a TV that has a captive mains lead or in some cases a power block which then means that a power socket needs to be sunk. Cutting in to wall, picking up the cable feeds, ensuring the right spec of any cable runs; do you have a 4K-capable source that might be supplying HDR in 10+ and DV formats, are you planning to game at HFR, do you need to connect a sound bar or sound system that might then be running Dolby Atmos? These are just some of the relevant and valid questions any self-respecting professional might ask prior to quoting for the job.

    After all that, there's the 'making good' phase. This might well involve a return trip the next day after plaster/filler has had time to dry sufficiently overnight. Suddenly £500 for what could end up as quite an involved 2-day job seems quite reasonable for someone with the skills and the tools and the insurance to carry out the job professionally to an acceptable standard.
     
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  16. foxhole

    foxhole

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    Could the plasterboard be fixed to studs on the brickwork? Are you certain it’s dot and dab? Any insulation ?
     
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