Mounting a thin wall

[Dabbler]

Hello, my first post, hoping someone can help me out as im at a loose end. Im trying to mount my 32inch TV to the wall, my only problem is that its plasterboard and probably about 3 or 4 sheets of 15mm plasterboard layed against each other (new build house, theres no cavity). Is it possible to mount a TV to a wall like this? The weight of the bracket and TV is approx 25kg, the bathroom is on the otherside of the wall so cannot bolt it or otherwise. Is there any fixings that will hold this kind of weight that do not exceed the width of the wall - a fixing around 35mm in length? Appreciate any advice.

Thanks.

 

[SimonH2]

It's not so much the overall weight, but the amount of "pull" on the upper screws. The weight will put the fixings in shear which is no problem even for standard wall plugs. The thing you need to do is keep the depth very shallow as the distance from the wall to the centre of gravity directly impacts on the tension in the upper screws. Also, pick a bracket with a large height between upper and lower screws.

As to fixings, there are things like toggles and brolly type fixings which mechanically open out behind the board.
For plugs, I've found Rawlplug Uno will take quite a load - specs here. Make sure you keep the hole small (ie don't oversize it), use the right size screws for the size of plugs (or right size plugs for size of screw if you prefer), and lightly soap the screw so it goes in easier with less risk of spinning the plug in the wall.

And of course, use multiple screws at the top where they are in tension. But not so many as to create a "tear here" perforation strip in the wall.


Best of the lot is if you can locate the studs and get at least one good screw into the timber.

 

[Dabbler]

Thanks for your reply simon, appreciate it.

The distance from the front of the TV to the wall will be 20cm so hopefully that is short enough as not to put too much pull on the upper screws like you described?

The fixings are my main concern. Finding the right ones is what is proving to be difficult. I cannot use the toggles/brolly type fixings that you mentioned as there is no space behind the board, the wall is literally a dividing wall between the room im mounting the TV and the bathroom and consists of what i can tell from a shallow hole ive drilled to be plasterboard on each side with some sort of plaster filler inbetween the 2 and results in a wall that is approx 50mm thick.

I had a look at the link and for plasterboard fixings the max load they can hold is 13kg or am i reading that wrong?

 

[SimonH2]

The distance from the front of the TV to the wall will be 20cm so hopefully that is short enough as not to put too much pull on the upper screws like you described?

Seen more, seen less.
How high is hte bracket on the wall side - from bottom of bracket to top fixing holes ?

I cannot use the toggles/brolly type fixings that you mentioned as there is no space behind the board, the wall is literally a dividing wall between the room im mounting the TV and the bathroom and consists of what i can tell from a shallow hole ive drilled to be plasterboard on each side with some sort of plaster filler inbetween the 2 and results in a wall that is approx 50mm thick.

Yikes Never come across something like that. Nearest I've seen is a commercial partition system (ie for offices and the like) and even in that there was at least an inch in between with a cardboard honeycomb.

I had a look at the link and for plasterboard fixings the max load they can hold is 13kg or am i reading that wrong?

Per fixing.

BTW, disclaimer, I'm only a DIYer myself.

 

[Sam Gangee]

I hate to add to your anguish but TVs should have an air gap behind for ventilation. I'd suggest that the gap should be one tenth of the screen size. So a 32" screen needs a 3.2" air gap at the rear to ensure an adequate air flow. If you ignore this, you could compromise reliability. Check the temperature at the rear on a hot day. It shouldn't exceed about 30°C. (If it does, the internal components will be cooking.)

One workaround is to screw vertical wood battens to the wall and screw the TV bracket to them. This minimises the shear loading on the wall, whilst maintaining an adequate air gap.

 

[SimonH2]

I hate to add to your anguish but TVs should have an air gap behind for ventilation.

Given that the OP has already stated 8" from wall to front of TV, I'd say that there's already a reasonable gap involved. Also, without having actually been looking, all the flat TVs I can recall the details of have had grills top and bottom with a solid panel over much of the flat back. SO air goes in at the bottom, up inside the case, and out the top - as long as vents top and bottom are unobstructed, there should be no issue.

One workaround is to screw vertical wood battens to the wall and screw the TV bracket to them. This minimises the shear loading on the wall, whilst maintaining an adequate air gap.

Shear strength isn't normally the issue. For shear, just one screw in a red plug would hold the weight of the TV up. Where the biggest risk of failure lies is in the top plugs pulling out under tension due to the lever action from the weight being offset away from the wall.

Lets throw some figures at it. Suppose the centre of gravity (CoG) of the TV is 6" away from the wall, and the distance from bottom edge of the bracket to top fixing holes is also 6". The tension in the top screws (ie trying to pull them out of the wall) is the same as the weight of the TV. Increase the height of the bracket by (say) 50% (to 9", ie 3/2 the distance of the CoG from the wall), and the pull out load on the upper screws is now reduced to 2/3 the weight of the TV.
Similarly, if you keep the bracket height the same but reduce the offset from the wall to only 4" (2/3 of 6"), then you also reduce the pull out load on the upper screws to 2/3 of the weight of the TV.

Stick the tv on one of those swivelling arms so the CoG can be up to 2' (24") from the wall, and the pull out load on the upper screws now goes up to 4 times the weight of the TV - that's why they tend to come with some heavy duty fixings. I've got one under my desk (bought for a customer who changed their mind) - it came with expanding bolts for fixing into masonry.

 

[ChrisFrost]

...what i can tell from a shallow hole ive drilled to be plasterboard on each side with some sort of plaster filler inbetween the 2 and results in a wall that is approx 50mm thick.

It sounds a lot like you have some form of insulated plasterboard for the dividing wall. [see link here for similar products].

These type of products on their own are not strong enough to form a large expanse of unsupported wall. If the wall is less than a board width wide (<1220mm) then it might be just that panel, but anything larger will require the support framework of timber or metal studs. You might want to try to find the vertical studs which run floor to ceiling to see if you can anchor part of the bracket there for a bit more strength. The rest of the fixings will have to go in the plasterboard. That's unavoidable.

Those plasterboard fixings that SimonH2 pointed at will take up to 11kg max each when used correctly in a 9.5mm plasterboard wall. You can add up the capacities to cope with the combined load. Four would do 44kg. Halve it to add a safety margin.

Whatever fixing type you decide to use I think you'll need to excavated a little hollow behind the hole to allow the barbs to work. That shouldn't be too difficult with a wire coat hanger and a little ingenuity.