Installing a TV wall mount on a hollow chimney breast

[Shanova]

Hi all,

I'm about to embark on my second attempt to install a TV wall mount on an unused chimney breast. The mount in question is a "pull down" mount that allows the TV to be lowered and so places strain on the wall plugs/ screws in a manner that a traditional fixed wall mount may not. The first attempt didn't end well with the wall mount and TV coming off the wall (see attached pictures) the first time the mount was attempted to be lowered.

As best I can tell, the chimney breast is made of brick that is around 16cm deep from the front of the wall to the inner hollow chimney space. However, the property dates back to ~1900, and it feels like the brick isn't very hard anymore (it was somewhat easier than I expected to drill the initial holes in and didn't require the use of the drill's hammer function). My builders tell me that the pink membrame revealed was placed to try to minimise paint cracking from the lime plaster applied on the walls.

The TV I'm mounting is ~24kg and the mount itself ~10kg. For the first attempt, I simply used the mount manufacturer's supplied wall plugs/ screws.

Can I ask:

1) Would it even be advisable to try again on the same wall with the same mount given how poor the first outcome was?

2) I'm guessing it would be advisable not to use the same holes anymore. Would leaving an ~8cm gap to the currently drilled holes be sufficient?

3) What wall plugs/ screws would be recommended to be used?

4) Should I be using a resin/ chemical plug or anchor bolts for the new holes? If so, what would be recommended?

Any help/ advice would be much appreciated. Thanks in advance.

 

[RandomGrinch]

4) Should I be using a resin/ chemical plug or anchor bolts for the new holes?

I would do this.
I have a Victorian stone built house, and the only thing that will hold rads to the walls are resin anchors and studding.
For an expensive TV on a pull down mount, even if it's overkill, resin anchors will give you some confidence that it's not going to pull straight off.

 

[Lucid]

I'll second that, @RandomGrinch If it's solid brick with a plaster finish and not just a skin of plasterboard, then resin anchored are my go-to for heavy duty installation work.

You'll end up with bolt threads (studs) sticking out of the wall. Washers and nylock nuts finish the installation.

Looking at your wall pic, it appears you have a cavity behind the board, or is that just the way the picture makes it look?

 

[foxhole]

Supplied fixings are usually cack, needs a 100mm screw x4. You can use concrete screw which will hold very well or not at all leaving you in no doubt if it’s going to stay up .

 

[Shanova]

Thanks all - you’ve convinced me to use a resin anchor and I think I’ve bought all the necessary tools (R-Kem II resin, caulk gun, compressed air, pipe cleaning brushes, threaded stud) to do the job. Went for M8 (largest that fits into the mount) x 110mm studs in the end (https://www.toolstation.com/fischer-ftr-m-threaded-stud/p55597)

I'll second that, @RandomGrinch If it's solid brick with a plaster finish and not just a skin of plasterboard, then resin anchored are my go-to for heavy duty installation work.

I do think it’s solid brick with a plaster finish and not just “skin of plasterboard”. Using a screwdriver to poke into the already drilled holes and it seems to be solid at all points around the hole even several cm deep (and even the back ~10cm in). Taking a pic of the inside shaft of the fireplace also shows:

Looking at your wall pic, it appears you have a cavity behind the board, or is that just the way the picture makes it look?

Hmm I’m not entirely sure what you mean. I think the pink “membrane” is taking up a small amount of space which leaves a slight gap between the plasterboard and the brick but there doesn’t seem to me to be a large cavity? Would this affect things? I’ve taken another pic with a flashlight in case it helps make things clearer:

 

[Lucid]

Hmm I’m not entirely sure what you mean. I think the pink “membrane” is taking up a small amount of space which leaves a slight gap between the plasterboard and the brick but there doesn’t seem to me to be a large cavity? Would this affect things? I’ve taken another pic with a flashlight in case it helps make things clearer:

You have the advantage of being there, so you can prod and poke about. The first photo could have been board - and something like Aquaboard does have a mesh coating. In fairness, you did say that your builder said the mesh was there to help the lime render stick, but that still leaves a question whether that's the same builder that did the fireplace work or a builder looking at someone else's work. Lots of fuzzy areas, so being cautious and trying to work out exactly what's what isn't really a bad thing. A picture might paint a thousand words, but no one said they'd be the right 1,000 words. LOL

Anyway, it looks like we know for sure now what you're dealing with. 120-year-old brickwork, with 120-year-old mortar to go with it, then a lime plaster render which makes sense since it's a breathable coating. That helps reduce the incidence of cracking where heat is involved.

The advantage with the resin is that if some of your holes hit the mortar gaps or the edges of bricks, the resin will still bond in a way that a simple mechanical fixing like a plug would struggle to do. The things to watch for are how fast the product sets - some are very quick - and of course getting the studs in at the correct depth and straight. If they sag during curing, then the bracket is going to be a sod to get level.

Good luck.