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I have trouble fixing my swinging chair to the ceiling of my living room (1970 house, central europe). The hook is suspended from a hook with a plate that is held in place by two screws. My problem is the structure of the ceiling, where the bottom part consists of some kind of hollow bricks, above which there is the concrete (I presume).

I tried attaching the chair with the two concrete screws that the manufacturer provided. These are 8 mm Fischer concrete screws, and I have used them successfully twice already, when I lived in flats with concrete ceilings. But here in my house the screws are too short to, so beyond the first cm or so in the brick, which is not that strong either, the screws dangled in the air and were not able to hold the weight. I then bought longer 10 mm Fischer concrete screws. These were long enough so that they would stick into the concrete for roughly 3 cm, see this sketch:

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At first I thought that this would hold, but after a few weeks the swinging chair crashed down on me (ouch!). I then remembered that the resistance when screwing the screws in was not comparable to the concrete ceilings. So I was not that surprised that the chair did not hold.

I am now out of ideas. What can I do suspend my swinging chair from the ceiling?

EDIT: I measured the screws again. The long 10 mm screws are 20 cm long. I will try again with 26 cm long screws and a hook-plate with 4 screws.

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    Find out exactly how the ceiling is made. Might have to make a hole big enough in the lower section of the ceiling to mount directly to the concrete or find where the spacers are and see if they are strong enough.
    – crip659
    Sep 13, 2023 at 14:00
  • You mean cm, not mm for those screw sizes right?
    – ventsyv
    Sep 13, 2023 at 14:05
  • I mean the diameter. I'm not sure how long they are, I need to remeasure them.
    – And
    Sep 13, 2023 at 14:07
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    Oh, @And, that's VERY important info. Both the answers you have so far were assuming the screws were 8 or 10 cm long, not 8 or 10 mm in diameter. Diameter is FAR less important than length in this situation (though it is important in the equation - if the screw is too thin, it'll easily snap as you swing). Good news is that usually, the longer the screw is, the thicker it also is.
    – FreeMan
    Sep 13, 2023 at 14:16
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    I suggest going to the local hardware store and asking someone what to use. Chances are if they are from the area, they've encountered that type of construction and know what works.
    – ventsyv
    Sep 13, 2023 at 14:19

2 Answers 2

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In your previous residence, the 8 cm screws went approximately 7.5 cm into concrete. In the new residence, the screw is going 3 cm, at best, into concrete, and the rest isn't going into much of anything. It's not in the least bit surprising that it fell.

If ~7.5 cm of penetration into concrete was enough to hold it in the past, it seems logical that ~7.5 cm of penetration will hold this time. You need to determine the amount of gap between the visible ceiling and the start of real, solid, structural concrete and add 7.5 cm to that measurement.

Since you say your 10 cm screw penetrated concrete about 3 cm, it seems the gap is ~7 cm. To span that gap then get 7-8 cm of penetration into the ceiling, you'll need a 14-15 cm long screw.

Of course, this doesn't take into account the fact that if you swing, you have lateral stress in the middle of the screw (where it exits the solid concrete) and that stress point could easily become a future failure point where the screw simply snaps and the portion through the brick comes crashing down on your head.

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You need to go at least 6cm into the concrete ceiling.

I also live (part-time) in the same region as you, and this is a common problem. Although the building where I live is much older than yours, the same issues exist: if you want to attach something to concrete, you have to go deep, at the very least 6cm or more. The problem seems to stem from the practice of adding many layers of finishing to walls, starting with maybe a cm of mortar, then layers of plaster, then that wallpaper thing that looks like textured plaster, plus a few hundred layers of paint, and so on. Three centimeters will not even break through the finishing layers before you go into the actual concrete. A few years ago I tried to hang some curtains, and bolts 3cm would not even hold the curtains -- it all fell and I made a huge mess.

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