Wall Impossible to Drill!

Olayemi

New Member
I need to install a shelf in my flat and I'm struggling to drill through the wall. It is above two doorways and I think there is a concrete lintel above them. The background is that I've had a set of sockets and my broadband connection box installed above the doorways (the reason for this is too long a story to tell). The sockets were specifically put there so that the router had a power source, with the plan to put shelving there afterwards for the router (and other paraphernalia that needs to plug into it) to sit on.

The sparky mentioned that he'd made a bit of a mess of the wall because he hit concrete and he knew the job of making it good was up to me (to be fair, it wasn't any worse than when sockets were done elsewhere in the flat). However, he got the backbox for the sockets in, so I assumed the concrete hadn't beaten him, but now I'm not so sure.

I'm using a Bosch Professional SDS drill in hammer drill mode, which I bought a few years ago when I came across other walls in the flat that my cordless B&D hammer drill couldn't manage. This is the first wall it's not been able to get through. I've tried upgrading my drill bit to the following Bosch Expert one, having read advice on the issue:

https://www.screwfix.com/p/bosch-expert-sds-plus-shank-masonry-drill-bit-12mm-x-215mm/395pf

That didn't do any better. I've checked the drill is not in reverse (as I know that'll be the first question!) and I've tried just persisting for ages, but I'm not getting any further into the wall. I also tried about 8 inches higher up (as this is closer to the height of the socket and I thought maybe the concrete doesn't go all the way up) and same problem.

Any suggestions?

It's taken me months of arguing with various broadband suppliers to find somewhere suitable to put the broadband socket and I really didn't think that the putting up of a shelf would be the undoing of it all!

I should all that it's a 1960s build, ex-local authority - from back when they built them really solidly...there is quite a bit of concrete involved!
 
Have you tried to drill a pilot hole first eg 4mm before using the large drill bit.
Why do you need a 12mm hole, that's large, what fixing will you be using ?
 
If you cannot get that bit to make a hole, you really do have a problem - potentially reinforcing bars.

Try dropping down by an inch and see what happens there.

Maybe a picture of tehgeneral area might help suggest an alternate.
 
Have you tried to drill a pilot hole first eg 4mm before using the large drill bit.
Why do you need a 12mm hole, that's large, what fixing will you be using ?

I haven’t tried as small as that, but I tried an 8mm higher up and same problem.

I was drilling 12mm holes because that’s what was required for the floating shelf fixtures I’d opted for:

Hidden Shelves Fischer Art.CPF Blister 2PZ
https://amzn.eu/d/2GguID5

I then abandoned these for different brackets that would allow me to drill higher up. 8mm holes because I’m using these, which I’ve found to work well in the past (and thus have loads of!):

https://www.screwfix.com/p/fischer-ux8-high-performance-universal-plugs-8mm-x-50mm-100-pack/20669

Even if I used the smallest plugs I’ve got, they’d only just go in (length-wise) and I certainly wouldn’t be happy to rely on them for shelving.
 
I've tried upgrading my drill bit to the following Bosch Expert one, having read advice on the issue
If you think a TCT masonry bit will get through metalwork, experiment on a piece of mild steel flat bar, galvanised water pipe or whatever, and see what happens.
 
If you cannot get that bit to make a hole, you really do have a problem - potentially reinforcing bars.

Try dropping down by an inch and see what happens there.

Maybe a picture of tehgeneral area might help suggest an alternate.

Picture attached (please excuse the messy plastering around the sockets - work in progress!).

On the left are the sockets that have recently been installed and on the right are the drilling attempts I’ve made. The intention was to have one clean looking shelf across the entire width just above the doors (there’s not really any room for me to go lower on account of the architrave).

I can’t use the wall to the left of the sockets because that’s where the fuse box is and so there are lots of wires chased into the wall running upwards from it into the loft space.
 

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If you think a TCT masonry bit will get through metalwork, experiment on a piece of mild steel flat bar, galvanised water pipe or whatever, and see what happens.

I’m aware that one would need different bits for metalwork, but at the time I didn’t know for sure that’s what I was dealing with and in any case, Bosch do actually claim that this bit will manage reinforced concrete:


I am a DIYer, who has simply come for advice, so perhaps you might consider a more helpful comment next time.
 
Thinking outside the box ...

1. what about getting three nice looking L-brackets with short uprights and fix those to the architrve around teh door and sit a shelf on those

2. What are the walls each side made of? If they are easier to drill, put a 25x25 batten on each and a shelf across those. Then maybe a couple of support blocks sitting on the architrave.
 
Is the shelf you intend to put up one of the lightweight type or a solid wood one? Also will you be putting anything heavy on the shelf, the router you mention obviuosly isn't a heavy weight item.
You'll have more problems drilling horizontally into concrete than vertically down as you can't apply as much pressure on the drill and bit especially when you're up ladders.
If you can't get a fixing I'd be trying along the lines of what FlyByNight has just suggested, resting the back of the shelf on the two doorframes and fix battens to the side walls. Depending on the weight of the shelf and what your storing you may be able to bond the side battens to the walls with an adhesive like CT1. Finally hold the shelf in place by drilling into the doorframes and battens and then use suitable screws to fix in down.
 
Thinking outside the box ...

1. what about getting three nice looking L-brackets with short uprights and fix those to the architrve around teh door and sit a shelf on those

2. What are the walls each side made of? If they are easier to drill, put a 25x25 batten on each and a shelf across those. Then maybe a couple of support blocks sitting on the architrave.

Thanks for your helpful response. I’ll have a think about these alternatives. There are a couple of things to consider…

1. I’m not sure the architrave that is currently there is going to stay. The contractors didn’t install what I wanted and installed it badly to boot (having measured for the shelf, it is definitely not in straight).

2. The wall on the left is problematic because of all the electricity cables hidden in it. There’s not really anywhere I can drill near the corner.

Nonetheless, I’ll think on it some more.
 
Is the shelf you intend to put up one of the lightweight type or a solid wood one? Also will you be putting anything heavy on the shelf, the router you mention obviuosly isn't a heavy weight item.
You'll have more problems drilling horizontally into concrete than vertically down as you can't apply as much pressure on the drill and bit especially when you're up ladders.
If you can't get a fixing I'd be trying along the lines of what FlyByNight has just suggested, resting the back of the shelf on the two doorframes and fix battens to the side walls. Depending on the weight of the shelf and what you’re storing you may be able to bond the side battens to the walls with an adhesive like CT1. Finally hold the shelf in place by drilling into the doorframes and battens and then use suitable screws to fix in down.

The shelf itself isn’t hugely heavy - it’s a piece of planed softwood timber that I’m intending to paint. I was, however, intending to store books on the rest of the shelf and this was the plan long before the router was even thought of. Seems I will have to abandon that ambition!
 
Get some decent wood. Make sure it's thick so it won't sag. Have the shelving cut to width of the room. And fix onto the two walls adjacent to the wall you're failing to drill.

Like a floating coving shelf. Mitre the shelf and fix as a floating shelf either side instead of along the back edge.

Or depending on weight, look into suspension systems to hang from the ceiling.

Two options there. But personally I'd just pilot a smaller hole using a mains sds drill. Battery drills are great but they're limited.
 
Get some decent wood. Make sure it's thick so it won't sag. Have the shelving cut to width of the room. And fix onto the two walls adjacent to the wall you're failing to drill.

Like a floating coving shelf. Mitre the shelf and fix as a floating shelf either side instead of along the back edge.

Or depending on weight, look into suspension systems to hang from the ceiling.

Two options there. But personally I'd just pilot a smaller hole using a mains sds drill. Battery drills are great but they're limited.

Thanks for the suggestions.

I have been using a mains SDS drill and that has not got me anywhere so far, but I shall consider smaller holes as Tricky Dicky also suggested this.

I’ve been looking into ceiling suspended brackets but I’m yet to find anything of the right size that suggests it’s suitable for that.

The reason I’ll struggle to fix at the sides is that the left hand wall is full of electrical wires because, as mentioned, the fuse box is on that side and lots of wires run upwards from it right to ceiling level.
 
Just asking, but you have got the drill set to 'rotation plus hammer', and not just hammer which is for chiselling? Took me few minutes when I first got my SDS to get to that stage!
 
A couple of thoughts:

How far into the concrete can you get? Rebar will usually be 30-50mm below the surface so if you get this far then stop you're likely on a bar and moving 10-15mm should get you past it. You've tried or had suggested all the obvious thing but maybe ensure you clear the hole of debris very frequently (this shouldn't be an issue drilling horizontally but worth a try). Also if you have a variable speed on the drill try different settings

I've seen 10s of thousands of cu.m. of concrete over the years can't conceive of any being too hard to get a decent drill into it especially when a sparky has managed to cut a box in.
 
Just asking, but you have got the drill set to 'rotation plus hammer', and not just hammer which is for chiselling? Took me few minutes when I first got my SDS to get to that stage!
Yeah, I kept checking this but it is in the correct mode!
 
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