So one day some time ago our iron stair railing going from the sidewalk to the stoop rusted through at the base of the posts and fell right over. I had a welder friend cut off the rusted portion and add a new section of 1" stock to both posts.

Now I need to figure out how to reinstall the railing. The existing holes are 1-1/2" to 1-3/4" wide at the top, but taper down. One hole is cleaned out to about 2", and the other to 1", the rest of the hole being filled with concrete and iron. From some research it seems a 2" wide and 4" deep hole should be secure enough, which I can then install the railing in, and fill with anchoring cement.

So my question is how do I enlarge and deepen the holes? Research seems to indicate a 2" core drill would be the best solution, but how would I keep the bit from jumping all over the place, especially considering I'm overlapping an existing hole? The bottom hole is only 2" from one edge and 3" from the other, so if possible I'd want to shift the center of the hole so I don't get any close to the edge.

image of holes in stoop and sidewalk

  • 1
    Have you considered surface mounting the posts?
    – mikes
    Dec 23, 2013 at 20:15
  • @mikes: Only briefly, reading that surface mounting is much less secure than setting the posts in the concrete. I'm also worried about getting too close to the edge. Many of the flanges I saw would put the anchoring screws only 1" from the edge, which seemed too close for comfort. Let me know if I'm wrong on these points though. Feel free to post an answer.
    – joshdoe
    Dec 23, 2013 at 20:27
  • May not even be possible, but consider moving the railing out and forward so that you can surface mount the posts to the side of the steps/stoop with expansion bolts through the iron posts. Less likely to rust out again in that configuration.
    – bcworkz
    Dec 24, 2013 at 2:34

1 Answer 1


Use the core drill you mentioned before, make sure it is deep enough, say 4" to get to the bottom of the iron stub. That is the standard mounting depth.

To keep the drill in place, drill a hole in a piece of 3/4" plywood big enough (1'X4'??)to lay on the stair you need to drill with the hole in the place that the old post is located. Stand on this while you use the drill to cut the hole. Get another body on it too if you feel you need to, but if you can maintain good balance you will be fine. drill it down about 1/2" and set aside the plywood and finish the depth of the hole. you can always chip a little of the concrete out, to go deeper, but you will find that a well placed tap with a hammer and chisel or steel pin to the side will release the plug that you drilled.

The plywood will stay in place very well with the pressure of you standing on it, it does not take a whole lot of pressure to keep it from "dancing".

If you can use a water fed core drill.

  • Be sure to break out the plug in a direction that does not stress the thin edge of the hole. On the other hand, if you break out the edge of the hole inadvertently, don't worry too much - you can patch that with the same mix you use to set the railing; But it will be easier if you don't break it.
    – Ecnerwal
    Dec 26, 2013 at 16:04
  • I've been delayed, but I plan to do exactly what you've both described to me, it sounds like it should work well. Thanks!
    – joshdoe
    Jan 8, 2014 at 21:14

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