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I rent a small flat in an old building. Since the walls are pretty brittle. Bricks are far apart, mortar has bigger stones then usual, so drilling can be difficult.

This is why the dowels are not sticking in the wall.

I thought about drilling downwards, to add a downward force to hold the dowel in the wall. Is there a better way?

  • I have rented a dozen places and never drilled a hole in the walls of any of them, so I am puzzled at treating that like something you have a right to do. If I was your landlord and caught you out doing it in such a fragile surface without permission, you'd be packing your things. Respect. I mean, I know how to get something like that to adhere, but it's way more intrusive than a tenant should be doing solo. If they requested it, I'd work with them. But it has to be landlord's choice since he will be the one stuck with the rubble if he's wrong. – Harper - Reinstate Monica Jul 5 '17 at 16:40
  • @Harper: That entirely depends on the country/culture. Around here it is perfectly normal to drill holes into your walls, no permission needed, landlords would give you a really weird look if you asked them; how else are you going to attach stuff? – PlasmaHH Jul 6 '17 at 8:55
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Brittle and old walls can be like a chocolate box... Drilling downwards doesn't help very much, in these walls the wall plugs and screws just behave like nails: they resist almost not at all to pulling forces.

Depending on how bad it actually is, you may need to do one or more of the following (maybe even different strategies depending on where in the wall you drill. Ever hanged a kitchen on a wall built out of post-war rubble?):

  • Use a smaller sized drill to make the plug a really tight fit
  • reinforce the plug with quickset cement/mortar or construction glue prior to screwing the screw in
  • take some matches (without heads) or toothpicks (with one pokey end removed) and hammer them in between the wall plug and the wall before screwing something in
  • after drilling, use a product that gets soaked up into the wall and acts as a reinforcing primer/glue

For big holes/heavy weights there are commercial systems available that will help with glue reinforcement.

Of course you can always do the last resort and do it like people did before they invented the wall plug:

  • poke a big hole into the wall, mortar in a piece of wood, screw to the wood.

Whatever you do, in these walls you have to massively derate the manufacturers specifications on load bearing abilities of the wall plugs.

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  • so drilling in, lets say a 45° degree angle would not increase strength? – Git Jul 5 '17 at 14:24
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    @gismo: No, you would need the same amount of force to pull the plug out of the wall. Depending on what it is you want to attach it might be enough since the majority of the load is pulling downwards, but then you would probably be using nails anyways, so my assumption with screws always is that there is a significant force pulling at it. Additionally if your bricks are really brittle you risk breaking of the part that the screw is now essentially hanging onto. The right answer for brittle walls of unknown strength is to reinforce and spread load. i.e. glue and bigger screws. – PlasmaHH Jul 5 '17 at 14:29
  • would upvote this comment, but not enough karma =( – Git Jul 5 '17 at 14:34
  • Any of these are well outside the realm of what a tenant should be attempting without formal permission. And it could go sideways and do some damage to the building. Another reason to pull in the landlord is he is probably more experienced at working this problem since he owns the place. – Harper - Reinstate Monica Jul 5 '17 at 16:49
  • @Harper: For the first, see my comment on the OP. For the second, usually they own the place, but do not live there and thus rarely had to deal with the things themselves. I for one have learned to deal with post war rubble walls only after living in one of the flats for a while myself. – PlasmaHH Jul 6 '17 at 8:57

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