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I am mounting a TV on a wall (see photos). There is a 7/8 inch gap between the drywall and the exterior, and a single metal vertical stud (Florida) as indicated. I want to center the TV, which is also indicated. I generally use toggle bolts for mounting on interior walls, but I do not think the gap is deep enough for them to open.

How should I mount here? Should I take advantage of the concrete (cinder block?) exterior wall?

mount on wall in position showing depth using cable outlet

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    @JoshDM- how heavy is the TV? and what's the approx. bracket weight? – ojait Jan 4 '16 at 4:45
  • I've hung this TV on this bracket before for two years using six toggle bolts. – JoshDM Jan 4 '16 at 11:52
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I would definitely take advantage of the block wall. I would use 2-1/2" tapcons with 1/4" fender washers straight through the drywall and than through some type of 7/8" spacer, and finally into the cinder block. The 7/8 inch spacer will prevent the screws from collapsing the drywall as the screws are tightened.

It would be best to use the largest TapCon fastener available. I believe they market a 1/4 inch diameter screw that has 3 versions: Flathead, Roundhead and Hex-head (hex's are easiest to grip and drive). The 1/4 inch screws will need a 3/16 inch concrete bit. I would use 4-8 of them depending on TV weight.

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    You will need a 7/8 inch spacer inbetween the drywall and the TV bracket otherwise the drywall will crumble as you tighten the concrete screws. – ojait Jan 4 '16 at 2:35
  • @ojait - you mean in the gap between the drywall and the concrete, yes? – JoshDM Jan 4 '16 at 2:54
  • Yes that is what I mean. – ojait Jan 4 '16 at 4:12
  • How would I get the spacer into the gap? – JoshDM Jan 4 '16 at 11:54
  • @JoshDM I would try gluing it to the end of thick copper wire and inserting thorough the opening you shown. Then when the screw is in place, snap it free, small amount of not so strong glue should do it. – Mołot Jan 4 '16 at 22:36
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Toggles into the stud / hat channel will be pretty strong,

Toggle bolt

you just have to select a toggle with small enough that the wings can expand - the wings have to be shorter than 7/8" - probably more like 3/4" - which depending on the brand will probably be 3/16. You'll have to trim the bolt to a length so that it almost reaches the block when it's all the way in.

I'd use a bunch of auger anchors, probably four on top and four on the bottom, as well.

Auger type drywall anchor

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You maybe able to trim the toggle bolts down to a size so that they can open in the 7/8 inch gap. It is the toggles wing that will dictate if it can be used or not. If you can find smaller toggles increase the amount you use to account for the decrease in holding power.

The 7/8 inch space is the hassle. You would need to install spacers in the space so when the bolts are tightened the drywall doesn't cave-in. If you can rip a 2 x 4 on edge to 7/8 thick would be ideal as a spacer. You may need to open the wall to install it. Screw it to the back of the drywall and now you can drill holes for tap cons and/or mount the bracket.

Another idea would be to cut a piece of 3/4 inch plywood so that it would fit to the inside of the TV mount (10"?). Cut the plywood so you have a 10 inch by 10 inch (if that is the measurement of the frame I.D). Cut two pieces and inlay them into the drywall at each end of the intended bracket location.

Secure the plywood to the concrete blocks with cement screws (4 each should do). I would now attach a strip of 1/2 inch plywood so it spans across the 3/4 inch plywood.

Attach the bracket with roundhead screws or lag bolts of the appropriate size.

  • For inlaying the plywood, are you suggesting cutting out large sections of the drywall and just attaching the plywood directly to the concrete and then screwing the mount into that? – JoshDM Jan 4 '16 at 14:51
  • You should remove the sections of drywall were the 3/4" plywood will attach to the block . I suggested 2 pieces one at each end. Than to bridge them with a second 1/2 inch length of plywood. – ojait Jan 4 '16 at 16:38
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What we did to hang really heavy furniture in similar situation was chemical anchor.

  1. Drill holes thorough drywall and into concrete
  2. Widen holes in drywall. See point 8 to find out how much wider is necessary
  3. Put baskets in concrete holes
  4. Apply chemistry - put resin and hardener in baskets in a way shown in manual
  5. Insert threaded rods
  6. Put what you need on the rods. Make sure you can put it on and off before resin hardens!
  7. Wait
  8. Put two nuts at each rod. That's why you need to make drywall holes bigger. Lock them against each other in a way that makes surface of the outer one at the same level your drywall is. Or just use one thick nut if you can find it. Or use one inch pieces of metal pipe that fits on your rods.
  9. put your metal thing again.
  10. Put nuts to hold it in place

Warning: it's easy to get rods to short or to long. To sort and you can't put nuts. To long and you can't put TV.

It works and it won't fail if done right.

Sorry for my lack of language skill.

Diagram of what I meant:

Just what I wrote before

I omitted the part about resin and mounting basket in concrete because manufacturer of chemical anchor will provide one best suited for fis product.

  • Apply chemistry? – JoshDM Jan 4 '16 at 23:00
  • @JoshDM resin, whatever makes resin harden, etc. into basket. Please edit if you know proper words. Manufacturers will get that better in their manuals. – Mołot Jan 4 '16 at 23:02
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I was inspired by ojait's inlay answer and combined it with the TapCon recommendation.

I got four pieces of 2" x 1" x 10" green-treated plywood and glued two pairs together using silicone.

plywood inlays

I placed the mount against the wall and outlined the screw hole locations, then laid each plywood inlay over four end screwhole outlines and outlined the plywood. Using a drywall saw, I cut out each side. I found an electrical surprise behind one hole. What are the chances?

outline with one inlay cut

surprise

I wrapped the mildly cut outer shell of the wires in electrical tape just in case, then pushed the wires aside and placed the plywood inlays. They stuck out more than the drywall, but there isn't much I can do about that. I put the mount over the plywood and again outlined the screw openings. I labeled the plywood: front right, front left, then drilled the holes using a wood drill. I made sure to bite into the backing concrete. I removed the plywood, then used the appropriate TapCon drill head to drill through the concrete at least an inch deep in the spots marked by the wood drill.

In the center, even though there was a gap, I used a self-drilling screw mount. I placed the mount over the holes and used 2 1/2" blue TapCon concrete screws with washers to hold the mount to the plywood, through into the concrete. I used the appropriate screw for the middle piece, but it was not necessary. Eight (six for the experiment) washered TapCon screws through plywood into concrete was enough to hold my 270lb body weight. Then I spackled over the edges where the plywood met the wall. Game room almost complete!

mount up

finished product

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Use 1/4-20 “Snap” toggles in the sheetrock. They hold 265 lbs. EACH in 1/2” Sheetrock. -Jef

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