How deep should I drill a pilot hole in concrete for a 2 inch screw?

Question

For fixing a 2 inch screw on concrete wall, how should I drill for good strength and no damage to the wall. I tried a 2 inch screw and drilled for 1 1/2 inch and later tried to screw it into the hole. But the problem I faced is that after the end of the screwing step, a circular portion came out of the wall wall and it became a very big hole.

Now how to fix this?

Answer 1

You should drill the hole at least 1/4" deeper then the screw depth. Also make sure to blow out all of the dust from the hole once you are done drilling.

If you use a concrete screw like a Tapcon you don't need to deal with plugs or expansion bolts.

Answer 2

A lot of variables there to make a proper answer:

Basic tenet of concrete use: Compression = good, tension = bad

• Wall thickness

  Drilling to half the wall depth for a threaded fastener (with extra room as Steven suggests) is the safest for embedding fasteners without stressing the wall itself.
  The screw point greatly magnifies the force at the tip, causing tension outward (bad). Sometimes a through hole, with threaded rod, thrust washers and nuts, is a better solution (puts concrete in compression (good)).

• Age of concrete, quality of concrete

  The older concrete gets, the stronger it gets (if allowed exposure to moisture). Poorly formed concrete (too much water, too little water, too low a percentage of Portland cement) will mean spalling (surface chipping), cracking.

• Fastener weight bearing requirement

  This question addressed the weight range of various fasteners.