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Why would plastic anchors pull out of the wall?

I have drilled holes in my concrete wall (good hard concrete) with a regular 8 mm concrete drill. They all seem like good holes and I've taken care to remove all remaining dust from the holes by blowing inside with a straw. My 8 mm plugs also go in with just the right amount of friction.

But when I start mounting the cupboard and really want to tighten the last bit, instead of just getting more secure, the plug starts creeping out of the wall! I've tried a couple of different types of concrete plugs, but they all yield the same result.

Is it a good idea to take some kind of filler material and jam it in together with the plug before mounting?

  • Your 8mm drill may be makeing a bigger whole then 8mm, so try a smaller drill. If a drill is bent a little, or you don't hold it 100 still, the whole get be larger then it says. – Walker Nov 27 '11 at 22:27
  • Excellent answer on the linked question Tester101! Upon examination of my screw length it seems like the problem is that they are too short so the plug never gets a chance to 'bite' properly. – Fylke Nov 28 '11 at 18:41
  • Well since the answer is really in the other post that Tester101 linked to and that one is almost identical to mine I think this one should probably be marked as duplicate and closed – Fylke Nov 30 '11 at 7:06

If they are coming out when you are tightening them, it might be that your hole was not drilled deep enough. The hole should be at least 1/4" deeper than the screw.

Those plugs also might not be large enough for the job. Concrete anchor scews (like Tapcon's) are a good alternative when you need more strength then a plug can offer, but don't need a large metal anchor. On large jobs (like attaching a deck to the house), you can epoxy a bolt in a hole like you suggsted.

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  • Love the tapcons! I second the motion to give them a try. – pboin Nov 28 '11 at 12:32

Depending on scale, you may want to use something like this: Socket Anchor - you may not be using a plug suitable for concrete.

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