I am trying to mount an LG 55UK6300 tv. I bought the Insignia 47" - 80" Fixed TV Wall Mount, and it comes with 2.75" lag bolts.

I tried drilling the holes as instructed but then my drill won't go any further than 1 to 1.5" into the wall before hitting a hard substance that looks like plaster on top of metal or concrete. I went out and bought a wall stud and it basically detected the entire wall as metal. so I figured I calibrated it wrong which was correct.

So I put the stud next to a wall socket where I knew there'd be no stud or anything. Then I drag it and it would beep where it said studs were, but drilling there resulted in the same problem. Max depth is 1.0" - 1.5".

So I drilled a larger hole and then took pictures and the results are:

enter image description here

How can I mount the TV in such a wall? I tried buying Butterfly/Toggle screws but they're too large to insert and anything smaller can't hold the 30lbs or ~14kg that is the TV. Drilling in different spots are the exact same.

(Full set of pictures at https://i.stack.imgur.com/atqer.jpg )

  • So what's on the other side of this wall? Jan 30, 2019 at 19:05
  • Stud sensors usually work by detecting density differences; if there's something dense enough throughout the wall, they are going to have problems. Also, note that outlets are usually next to studs, so putting the detector next to a outlet may not do what you want. Jan 30, 2019 at 19:50
  • Where are you located, and what sort of building (Single residence, apartment, etc)? That may help people figure out what the wall is made of. Jan 30, 2019 at 19:51
  • I am located Toronto, Canada and it's a Condominium. Behind the wall seems to be concrete or plaster. It looks more like an extremely hard plaster (or combination of both plaster on top of concrete?). With the concrete drill bit, it barely made a scratch..
    – Brandon
    Jan 31, 2019 at 15:01

2 Answers 2


I've had great success using 'TOGGLER ALLIGATOR A6 Screw Anchor, Plastic, 1/4" Diameter, 1-1/8" Length, #6 to #12 Threads' in masonry, concrete, and drywall walls for years. They have tremendous holding and shear capacity. Especially in any solid wall type. They require you to drill a 1/4" hole using a masonry bit. In your case you will probably need to use, buy, or rent a hammer drill to drill into the concrete wall.

You can these online through HomeDepot or Amazon. They are really the only anchor I use any more since they are rock solid and also removable if you ever want to patch the wall.


If the concrete is thick enough you can try using concrete anchors.

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