Installing cantilever TV wall mount on battened plasterboard wall

Callan

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Hi All,

I want to install a cantilever TV wall mount on an external block wall that has 2" battens and plasterboard.

I had tried using 120mm core fix as I had assumed this was a dot and dab wall. The bracket came away from the wall shortly after the TV was mounted (an expensive assumption). 

I've since cut into the plasterboard to reveal what's going on. The plasterboard is fixed to 47mm x 44mm battens. With 65mm between the wall surface and the block, the gap is too large for the corefix to work.

I'm thinking of adding horizontal battens with masonry screws to the block so there will be no void when I replace the plasterboard. What length screws should I use to fix these battens?

The bolts included with the mount are 95mm. I assume these won't work as they would have to go through the wood and concrete using plugs. Can anyone recommend a fixing? Would something like this work https://www.screwfix.ie/p/dewalt-blue-tip-2-flange-screwbolts-10-x-120mm-25-pack/323ht

Any other recommendations on what to do. The TV will have a soundbar mounted to it and both will weigh over 25kg.

I attach pics of the wall.

55" TV weighs approx 19kg and will have a 6.25kg sound bar attached to it

Wall mount - https://www.sanus.com/en_GB/products/tv-mounts/vlf728/

Sound bar mount - https://www.sanus.com/en_GB/products/speaker-stands/wssatm1/

Many thanks.

10-10-20

If the block is 100mm (standard solid block size) then an 80mm hole in the block (don't over drill too much) and a >40mm batten will work with a 120mm masonry screw, leaving a gap of ~20mm to the plasterboard. I'd fill that 20mm with another wooden spacer then, doesn't need to be super-screwed in.

Then I'd use a good wood screw with a wide head to complete the the mount into the battens, predrilling, and the mount should pull tight up against the battens and be good and solid.

https://www.screwfix.ie/p/timberfix-hex-socket-structural-timber-screws-6-3-x-65mm-50-pack/48621

hesker

Is that your air-tight barrier directly behind the plasterboard, with holes in it.

If it is you’ll need to reinstate that.

policarp

Fix a batten or two or a piece of ply or MDF to the studs in the wall.

Then mount your brackets.

Callan

https://www.boards.ie/discussion/comment/120619187#Comment_120619187

Thanks for this. The block work is cavity blocks. Should I still use 120mm screws and aim to screw into the centre of the blocks. Or would 80mm screws (47mm for batten + 30mm for block) be more suitable?.

Callan

https://www.boards.ie/discussion/comment/120619441#Comment_120619441

Yes you're correct. The holes are from the corefix. I plan to patch this with new plastic and duct tape. All though I will be putting holes in it again when I screw the mount the the battens.

Tefral

I use Gripit fixings for what you are describing OP

https://www.gripitfixings.co.uk/products/gripit-rhinofix-plasterboard-fixing-kit-8-pack-purple

You can get them in screwfix

If you zoom in on the picture it will show you how they work,

eusap

Can you mount the bracket directly to the wall and then make the plasterboard neat with a slot for the arm? How often do you plan on moving the bracket? I was told before when calculating the weight allow for 3-4 times the weight of the TV when using a cantilever as that will be the downward force at the tip

Callan

https://www.boards.ie/discussion/comment/120626665#Comment_120626665

I had though of that, but as it's an external wall it will need to be insulated and the vapor barrier will need to be reinstated.

10-10-20

https://www.boards.ie/discussion/comment/120626295#Comment_120626295

With cavity blocks I would use a more suitable fitting such as this:

https://eshop.wurth.ie/Product-categories/Cavity-anchor-W-MH-B-bolt-nut/31124505020214.cyid/3112.cgid/en/GB/EUR/

greasepalm

When i was getting my tv mounted on a similar bracket on an indoor wall and was paper Mache as house is very old.

What he did was to put a thick slap of plywood i think on top of panel wall and loads of screws to secure it and mount secured .

I would assume with added weight 2 bolts in top to hold it it place means not relying on wood screws and the top is where it will pull off from.