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Discussion Starter · #1 ·
So I'm a beginner in using a drill and planned on mounting my 70-lb. TV in my bedroom's concrete wall. The TV mount bracket that I bought included #12 lab bolts (6.3mm diameter) and 10mm plastic anchors. So I bought a 10mm drill bit for my drill and began drilling at 4 points in my wall. Here are my questions:

1. When you use a 10mm drill bit to drill, should you expect a hole that is exactly 10mm? I measured the 4 holes I drilled and I got 11mm, 11mm, 11.5mm, and 12mm :(
2. When I inserted the 10mm plastic anchors and try to screw in the lag bolts, the anchors just don't grip the concrete and so they just rotate together with the screws. When hammering them in, should they go in the holes easily or have a bit of a resistance?
3. How do I remedy my situation? Can I perhaps buy 12mm anchors and bigger screws? Would 12mm anchors fit in the holes I made or can I force them to go in by using a hammer or something?
4. What screw gauge should I be getting for 12mm anchors?
5. Also, while I was drilling I noticed that at maybe around 60mm-80mm in the drill bit just went though which means that I drilled into a hollow section of the concrete. Is this fine? Would that length be enough for the plastic anchors to grip onto when they expand when the screws are in? Is there a trick to determine how exactly deep are the holes before the hollow part?

Sorry for the noob question and I'm really hoping for your help. Thanks.
 

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It sounds as if you drilled into a CMU (Concrete masonry unit) or concrete block wall, not solid concrete monolith. Can you confirm? Can you post a picture of what you have done?
 

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Discussion Starter · #4 ·
It sounds as if you drilled into a CMU (Concrete masonry unit) or concrete block wall, not solid concrete monolith. Can you confirm? Can you post a picture of what you have done?
I honestly have no idea. Is this something that I can check myself or should I consult our property management officers (I live in a condo)? Here are some pictures of what I did (nevermind the chipped of paint, they used very cheap painting that bubble out through time):

632796


632797


First thing I recommend is that you ditch the plastic anchors and get lag shields.

View attachment 632795
That's what I thought. Are lag shield always more powerful than those cheap plastic anchors? If so, how big of a lag shield should I get? The TV mount bracket that I'm mounting now included #12 screws and 10mm anchors.

After I'm successful with mounting this, I will mount another TV using the AEON-40200 which includes 8x70mm lag bolts and this mount is rated up to 150lbs.

If I were to replace all of these screws with lag shields, I want to get a size that's practical (not small but not too big of course).
 

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Lags work very well in solid concrete. In block or any concrete wall with cavities they can break out.

How heavy is this television? 3/8" lags seem like overkill.
 

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Discussion Starter · #7 ·
What's the difference between the concrete sleeve anchors vs. the ones with the lag shields?

Lags work very well in solid concrete. In block or any concrete wall with cavities they can break out.

How heavy is this television? 3/8" lags seem like overkill.
What would you suggest then?

I'm mounting two TV's in two mounting brackets on the same wall and are a few meters apart. 1st TV is 70 lbs (55") as it's an older one. The 2nd TV is 55,6 lbs (also 55") as it's a 2019 OLED model. The lags I have (included with both mounts) for TV1 are 1/4" (6.3mm) and for TV2 are 5/16" (8mm).
 

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Kevin are you sure thats a concrete wall? I zoomed in on the picture and it looks like some type of wallboard. Doesn’t look like its thick enough for concrete.
The anchors that come with the mounting bracket are almost always too cheap and wrong. The lead shield will work for concrete. If you have walboard you might try something like this ... something with wings that open inside the wall.

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Discussion Starter · #9 ·
When you say wallboard are you pertaining to a wood wall? This is definitely concrete. I live in the Philippines and asked around. They said that for normal walls (non load bearing) in our country, a wall made of hollow blocks is common. Poured concrete (solid walls) are only used for load bearing walls like pillars, walls that support roofs, etc. So I'm guessing this wall is made of hollow blocks.
 

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Discussion Starter · #10 ·
Also, how were you able to estimate the wall thickness from the picture alone? When I drilled earlier, the hole started become hollow somewhere between 60mm-80mm so that should tell us something. I wanted to measure the exact depth before it becomes hollow but I don't know how.
 

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60 mm is almost 3” in real measurements ... thats pretty think for a concrete block. Actually not thick enough for a solid block, but too thick for breaking through into a cavity.

I zoomed in real close to this picture, and it kinda looks like i can see a thickness of a sheet product. Maybe not. Either way, if you have broken through into a hollow, you need an anchor with wings.

To get actual thickness, take a piece of wire about 6 or 8 inches long and bend an L in one end, small enough to go in the hole. Poke it in the hole and pull it back until it catches on the inside of the wall, and mark the wire where it meets the face if the wall.

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Discussion Starter · #12 ·
So I asked the property management office about how our walls our constructed here. He said they are made out of concrete hollow blocks with poured concrete (so no hollow section) plus embedded steel frames (probably rebar).

I still did my due diligence and followed your recommendation about using a metal wire and bending one end to an L shape small enough to go inside the holes. I got varying results which makes it more confusing to me. I put the wire in the holes, exerted a bit of force around the circumference of the holes, and pulled back each time. In some parts of the circumference, I can hook into something (indicating there's a hollow part there somewhere) but in some parts there is none. If it was really hollow, I should have gotten consistent results (hooking action) all around each hole. So I'm not convinced that the area behind the hole is hollow all around which means those drywall anchors won't work too.

To be triple sure though, I got my Datavac blower and pointed it to one of the holes so that it gets blown with pressurized air. The air came out of the three other holes. I did the same for the other holes and I get the same result. This means that all 4 holes are connected by some hollow channel somewhere, no?

The property management officer also recommended I use expansion bolts and add two more to the existing 4 holes that I have to make it even stronger.
 

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Most likely you have drywall on furring strips over concrete block. Never depend on drywall alone to support weight.
If so you have 2 choices.
Lag bolts will need to be in the concrete not the drywall, aka plaster board. So the hole in the surface you're looking at will need to big big enough to pass the anchors thru and into the concrete.
Your other choice, and this might be better, is a plywood board attached to the furring strips or, even better, Tapcon- ed thru the plaster, the furring strips and into the concrete.
To comment on your original questions you will find that it pays to get the holes for whatever fasteners you use to the right size AND as close to straight in as possible.
If plywood doesn't appeal you could chose a straight piece of for or oak but you'd want to avoid weak or soft woods such as Poplar or some pine.

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Discussion Starter · #14 ·
Most likely you have drywall on furring strips over concrete block. Never depend on drywall alone to support weight.
If so you have 2 choices.
Lag bolts will need to be in the concrete not the drywall, aka plaster board. So the hole in the surface you're looking at will need to big big enough to pass the anchors thru and into the concrete.
Your other choice, and this might be better, is a plywood board attached to the furring strips or, even better, Tapcon- ed thru the plaster, the furring strips and into the concrete.
To comment on your original questions you will find that it pays to get the holes for whatever fasteners you use to the right size AND as close to straight in as possible.
If plywood doesn't appeal you could chose a straight piece of for or oak but you'd want to avoid weak or soft woods such as Poplar or some pine.

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How were you able to conclude that? I don't see how this could have a drywall over furring strips inside. The wall divider in this condo unit is made out of drywall with furring strips inside. If it were, I would have seen wood dust while I was drilling, wouldn't I?
 

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Discussion Starter · #16 ·
I see. Well, I'm not sure if I need to believe the property management officer about this wall being made out of CHB's and poured concrete. I originally planned on mounting this over drywall (with the plywood board technique explained above) but then I had a choice of using the concrete wall instead which will make things easier.

Any other suggestions to confirm what type of wall is this? Or maybe go ahead and just use sleeve anchors and probably add two more holes (for a total of 6) just to be sure?
 

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When you drilled through this wall, did you use a hammer drill with a masonry bit? A regular drill and bit (i.e. for wood, metal, etc.)?

If you used a standard drill (only rotates, no hammer action) and a regular drill bit, how easily did it make it through all these materials? Concrete is a bit difficult to get through without a hammer drill and masonry bit. Not that it can't be done, it just takes a little longer and is usually a noticeable difference over going through wood and drywall. Did it drill right through all the layers of the wall without much issue?
 

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Discussion Starter · #18 ·
I have a hammer drill but only takes up to 8mm drill bits so I had to borrow a drill that can take 10mm bits. The drill I used was a Makita M0600. When I search online, it seems that there are two submodels for it, one a regular rotary drill and another a hammer drill. I'm not sure which one was it because it only mentioned M0600 in the body. I would guess it's a regular drill because I didn't hear any hammering action. But I did use a 10mm masonry drill bit.

The first layer was very hard to drill through and it took me a long time. I'm guessing that's the plaster layer. And if i had to guess, at about 50 to 60mm deep, I felt it easier to drill (still with a bit of resistance but much less) and I think this is the block layer already, right?
 

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Discussion Starter · #20 ·
I have a Bosch GBS-12V30 and I had to extend the length of 4 x 10mm holes from about 80mm to 90mm. I used the tool to drill through 10mm of what I think are already hollow blocks so it's not that very hard compared to the first layer of plaster (when I used a different drill that I borrowed). I forgot that even though my drill accepts up to a 10mm chuck it is only rated up to 8mm when drilling in masonry.

Do I have to worry about anything breaking because of what I did?

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