Drilling into concrete floor (driveway)

28 Oct 2010
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United Kingdom
I have a carport which is showing signs of age and the supports need to be replaced. The 'easiest' way for me to do this is to resupport the canopy on 6 2.4m fence posts. I need to attach the fence posts to the ground, which is a concrete driveway laid many years ago. There's a very high proportion of ballast/stones in the concrete.

I'd prefer to drill into the concrete and fix fence posts to it rather than any other option.

Questions are: What sort of drill bit should I use? I have a hammer drill but last time I tried something similar it wasn't very successful as the masonry drill bit didn't want to penetrate the stones.

Assuming that I can drill holes - how do I then fix the fencing supports to them?
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Hire a chunky SDS drill and use anchor bolts to fix.
The hire shop will give you the right gear if you tell them what you are doing.
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SDS+ is a type of electric drill chuck (and the drills to fit it). They have a tapered fit rather than a 3-jaw chuck like a small electric drill. They are more suitable for heavy work. Your local hire shop will have one (a good one is quite expensive to buy)

however, if you have a good strong concrete base, see if you can get steel post shoes that are intended for building in to new concrete, and have a single steel bar (barley-sugar twist reinforcing rod with nibs) sticking out of the bottom. If you push this into a fairly close-fitting hole (or a loose hole with some wet mortar in it) it is not going to come out without a pretty strong pull direct along the axis. This will not happen just from wind loading but if you ever have to, you can get them out with a big bar.

these post sockets also lift the post slightly above the ground, so that with a good soaking in preserver, they have a good chance of not rotting for some years.
I've just had a kennel block installed onto a new base. The guy fixed the metal panels to the concrete using a normal hammer drill to drill the holes and then embedded some bolts into the holes with some sort of fixer which came from individual sachets. I think they were Hilti but I've no idea what they were. I'll certainly get the SDS drill but the bolt fixing idea seemed quite good to me. Any ideas what that might be?

BTW thanks for the help so far.
probably an epoxy resin which is good for reinforcing holes in concrete and getting a very good grip. Possibly your concrete was a bit crumbly or the hole a bit loose.

You can get it in an injection gun (Fischer brand) for this purpose, I have not seen it in sachets before.

An economical alternative I use a lot is no-more-nails or similar before inserting a plasplug in a poor hole.
A woman is more to my taste, but I'm not one to criticise.
some sort of fixer which came from individual sachets. I think they were Hilti but I've no idea what they were.



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