Im concrete, How deep does the hole have to be so that a 3" anchor sleeve is most effective?

I'm drilling in very hard concrete, and I've drilled about 2.5" in depth. Is that good enough?

They'll be used to anchor these simpson ez bases.

  • Get a hammer drill and concrete bit. Go full Jul 4, 2018 at 16:00

2 Answers 2


IMHO full depth = full strength.

If you don’t go full depth, will you add washers to make the anchor fit snug to base?

  • I can imagine the instructions for a particular nominal 3 inch sleeve anchor stating to drill a hole 3.25 in or 3.5 in deep. On the other hand I can imagine a particular "3 inch" anchor requiring a hole only a 3 in hole or even less depending on the thickness of the part being clamped to the concrete. Jul 4, 2018 at 10:23

You can get the engineering info including shear and tension strength for that fastener from the manufacturer's web site.

The tables in that document show values for a minimimum embedment of 1-1/2". It's probably stronger at 2-1/2" or 3" but you couldn't count on it.

Without knowing the actual loads involved nobody could say whether this is enough, depends on more than just the fitting you're using.

Note that if they stick up too much you'll wind up trimming the excess off the bolt, which might be more work than just drilling another 1/2". With a decent bit and hammer drill that should not take long at all.

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