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My wife & I spent a fair amount of time setting up a VideoSecu heavy articulating wall mount in a position & height that we liked.

Problem is, the top-left lag screw (5/16" thick, 3" long) broke in half once it got all the way in the stud (1.5" wide).

The rest of the screws were already tightened. What is the best way to proceed?

As far as I can tell, my options are:

  1. Screw extraction, then use a larger lag screw. This seems iffy since 1.5" of the screw is lodged deep in the wall (drywall around 1" thick, it broke off beyond that depth).
  2. Leave old screw, drill new lag screw in a different direction (in this case unfortunately it would have to be UP at an angle, but the rest of the mount looks pretty damn sturdy so mostly worried about stud integrity).
  3. Move everything - take out the 3 existing other lag screws, move entire TV mount installation up/down. In this case I'm worried about the stud also losing integrity by removing the 3 very large lags nearby (& since we'd be screwing the new installation in nearby, ~3" up/down).
  4. Move mount to entirely new stud location. This is likely not possible as there aren't any other studs in the house that will fit the TV near our living room.
  5. Abandon project after removing installation.

Obviously #5 is the worst solution. My current thinking is #2 since it's the path of least resistance but I don't know how worried I should be about it vs. the other options. Or perhaps there is another idea I haven't thought of?

Wall mount weight: ~50lbs. TV weight: 60lbs.

All help veryyy appreciated!! We are totally stuck!

Results

At Grant's suggestion, we screwed in a new 5/16", 3" long lag screw next to the existing broken off one. So far so good, can hold the very large TV.

One interesting thing to note - regardless of how much I piloted, the screw was still very hard to get in. Perhaps the stud was tough, but I still needed to use an open socket wrench with a fair amount of torque to get the last 1" in. Drywall surrounding this is a mess, but intact so is still providing adequate support to the stud & mount.

I will update this thread in a month or so, or if there are any problems in the meantime.


Update, Oct. 2015: No issues to report.

  • Doesnt help you now, but if you are moving it and reinstalling elsewhere, predrill your holes. Then the bolt will be less likely to break. – Grant Aug 16 '15 at 16:41
  • Yeah, I figured in the end the issue had something to do with the bit size. We definitely pre-drilled the holes (I used a 7/32" bit) but it did start getting pretty tight near the end there - lesson learned but I still have a half-installed mount in the wall :/ – Sitric Aug 16 '15 at 16:42
  • Is there enough room to drive another bolt in right beside the broken one and still hit the stud? It looks like they go into slots on the mount, so maybe you can get one in beside it. – Grant Aug 16 '15 at 16:51
  • Yes, yes there is - good idea - I guess my main underlying concern would be would I screw up the stud by screwing something in so close to the previous one? (crack it, strip the wood, etc.) – Sitric Aug 16 '15 at 17:05
  • It was really obscure but through SPAX's website, I found some specs for their products (spax.us/images/pdfs/Spax_Overview_Bro2014.pdf). Their lags are apparently grade 5 and Home Depot sells them. – xster Dec 16 '15 at 6:57
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Luckily your mount has slots for the bolts so you have a bit of room to work. Get another (stronger, higher quality) lag bolt and put it in right beside the broken one.

Leave a tiny bit of room between them if you can, but make sure it still solidly hits the stud.

Predrill the hole. To find the right size, hold the bolt up behind your drill bit. The drill bit should cover the entire shaft, but not the threads. Make sure you drill to the same depth the bolt will go to.

Rub the bolt threads on a candle or bar of soap to lube it up a little if you think it is going to be hard to drive in again.

Drive the bolt in slowly. Don't use a drill unless it has a low torque screwdriver setting. You might want to tighten it with hand tools anyways so you don't risk snapping this one too. There probably isn't room for a third try!

  • Assuming it's dead center and 5/16" bolt, that is 5/32" from the center on one side - that leaves 3/4" (3/2 * 1/2) - (5/16 * 1/2) 5/32" = 19/32" on side A. If I use another 5/16" lag, then that gives me 19/32" - 10/32" (5/16x2) = 9/32" (less than a 1/3" to wall). That already seems pretty close & it's likely that I'm not dead center - wouldn't I be better served by angling it up slightly? (assuming drilling so close to the other screw isn't going to ruin the wood?) – Sitric Aug 16 '15 at 17:22
  • @sitric if you aren't dead center, I would try to figure out which side the broken one is on and go for the other side. Angling it means you put all the forces on the bottom of the bolt head, instead of distributed evenly. As long as it is all inside the stud it should be fine, just try to put it as close to center as you can with the old bolt there. – Grant Aug 16 '15 at 17:32
  • OK - that sounds totally sensible (also, thanks for all the responses) - I'm going to now be paranoid & ask "Why won't I destroy the stud?" I'm just struggling to understand how I won't splinter the wood all over the place with a large hunk of metal nearby – Sitric Aug 16 '15 at 17:36
  • @sitric you avoid splintering the wood by predrilling well, and driving the bolt slowly and gently. If it gets stuck, don't force it - pull it out and rub on a candle to lubricate it, and make sure you drilled deep enough. The stud around the broken bolt is still pretty solid - its just part metal now :) Also be careful not to hit the old bolt when drilling - your drill probably won't like that. Just be slow and gentle and everything will be fine. – Grant Aug 16 '15 at 17:41
  • Alright - I think we're going to try this out. If it works, I'm also thinking of installing a "safety" lag below it (on the outside of the mount, 50% on mount 50% on a shim) just in case it pops out at some point I'll have a chance to take it down before the TV shatters :P. I'll update after its complete – Sitric Aug 16 '15 at 17:53

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