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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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.– jwh20May 16, 2020 at 22:52
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How deep does it need to be? It's slightly longer than the length of the screw.– dfitzgeraldMay 16, 2020 at 22:56
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The Tapcons that I have used list the required pilot hole size and depth on the package.– jwh20May 16, 2020 at 22:59
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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 DefenestrateMay 16, 2020 at 23:36
1 Answer
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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