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I'm trying to install some shelves in my apartment (brick/concrete) but when I drill holes the walls almost seem like they're made of sand. I'm not able to securely fix the screws (I'm using wall plugs) and the shelves appear like they're going to fall down at any minute.

Is there anything I can do about it? I was wondering if I could use some material inside the holes after I drill them (and before putting the wall plugs) so I can make the screws stay firm in their place.

Any tips?

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6 Answers

up vote 5 down vote accepted

Are you sure you are not drilling between the mortar? That is the weakest point to drill.

There are a couple different things you can do. I assume you are using concrete anchors so you can apply a generous coating of Loctite Metal and Concrete Epoxy onto the anchor before you insert it into the hole.

The other option is to take furring strips (pressure treated 1x4's) and attach them to the wall with blue concrete anchor screws, at least 2 and 1/2 inches long. These should make a good thread and the furring strips will add to the support structure. Space your anchors 2-4 inches apart vertically and on-center.

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Using epoxy seems like a simple thing to try and see if it works. Gonna try that first :) –  Rodrigo Sieiro Jul 30 '10 at 14:58
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A better solution might be to build a framework to support the shelves rather than trying to "bodge" (as we say in the UK) the holes. What you need to do is spread the load from the shelves over a larger area.

Without knowing the layout of your walls it's difficult to suggest anything definite but if you had an alcove you could fix vertical battens up the sides and then hang the shelves between those.

Another alternative is to use a glue such as "No Nails", however, you need to check that it's suitable for your walls and can handle the load.

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+1 for the framework workaround, although I don't agree with the "No Nails" alternative. –  dag729 Jul 28 '10 at 20:44
    
@dag729 - It's not always suitable, but does help to spread the load if you have got soft brickwork. –  ChrisF Jul 28 '10 at 20:46
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I've got two ideas.

The first is to use a chemical wall plug, but the second has a requirement.

If you can drill through that wall, I suggest to put on the other side of the wall a metal plate (width, height and thickness are up to you that know how many Kilograms the shelf it supposed to get on itself), then make three holes in the shape of a triangle (with the single vertice facing the floor and the other two facing the roof) and use one screw thread for each hole.

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Now I'm curious: what is a chemical wall plug? Never seen one of those, and googling didn't help. –  Rodrigo Sieiro Jul 30 '10 at 15:15
    
The chemical wall plugs are a kind of special plugs with two chemical compounds that, mixed together, create a very strong mixture, capable of a lot Kg/cm more than normal plugs (for instance "fischer" type). –  dag729 Jul 30 '10 at 17:51
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You can use different fittings, such as frame fixings (the kind of thing you'd use to hold a exterior door frame or window in it's hole). Also, you could fix up a batten with lots and lots of long rawlplugs and fat screws (two rawlplugs per hole, one deeper so the whole screw is biting into rawlplug), then screw your shelves to that nice study wood batten.

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What color is the dust that comes off when you drill? If it's just white, you could be just drilling into the plaster instead of the actual solid material underneath. Try drilling deeper holes and see if you hit a more solid surface.

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The dust starts white, but after a couple inches it turns red. The main problem is that first couple of inches: I can drill through it with a cheap driller and using almost no strength at all. Maybe the problem is I'm using too small wall plugs. –  Rodrigo Sieiro Jul 30 '10 at 15:06
    
Yeah, going deeper might just to the trick. –  Ates Goral Aug 3 '10 at 15:31
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i recently moved into an old brownstone and have a similar situation, i was recommended to drill through the plaster into the brick (which is directly applied to the brick) and then fill the whole with epoxy. once set, i was told i can drill the screws directly in the epoxy and it should hold the shelves. does anyone have any comments regarding if this will work or not?

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I used epoxy and it worked great. But I still used the anchors. Put the epoxy inside the holes and then insert the anchor while it's fresh. Then you can wait for it to dry before fixing the shelves. –  Rodrigo Sieiro Feb 11 '11 at 11:37
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