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I'm attempting to use tapcon 1/4in by 2.75in concrete screws to affix something to a wall of poured concrete, but it's only going about 3/5 of the way in before refusing to go any further. I used the recommended tapcon drill bit size so I don't think that's the issue, and I've also air blasted all the dust out. What else could it be? Do I just need a more powerful drill? A smaller size screw?

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https://imgur.com/a/PC2wkQS

  • Are you sure you have drilled the pilot hole deep enough? Check it with something that will fit and be sure it's as deep as it should be. – jwh20 May 16 at 22:52
  • How deep does it need to be? It's slightly longer than the length of the screw. – dfitzgerald May 16 at 22:56
  • The Tapcons that I have used list the required pilot hole size and depth on the package. – jwh20 May 16 at 22:59
  • What kind of drill are you using to drive the screw? (It might just be underpowered.) You might also try reversing a bit as you stall out. – Aloysius Defenestrate May 16 at 23:36
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That's far too long a screw for that application. 2-3/4" screws are designed for mounting 2x4 lumber, for example, which would leave just 1-1/4" of penetration or so.

Concrete screws, especially thinner ones like that, should only engage the concrete maybe an inch or a bit more. If you try running that in with a stronger drill it'll almost certainly snap.

Try the 1-1/4" screws, and be aware that running them in more than once usually results in the threaded concrete failing due to the grinding effect of insertion. They should be a once-and-done install. Move to a new hole if that one doesn't seem to hold with a shorter screw, or use some epoxy to rebuild the bond.

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    This is what I ended up doing and it worked great! – dfitzgerald May 17 at 1:46

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