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I need to install Ikea BOAXEL shelves on a 85-80 mm thick gypsum block wall (it is no plasterboard). My biggest concern is that I have never worked with this material before, and I'm not sure if I'm choosing the right anchors for this wall.

BOAXEL is a shelf system that is mounted on vertical mounting rails. I plan to install 4 rails, spaced 60 cm apart. In total, I want to place 9 shelves on these rails, each shelf is going between 2 rails. The rails allow for adjustable shelf heights.

A single shelf weighs 3 kg and has a maximum load capacity of 24 kg. Its dimensions are 60 x 40 cm. The weight of the rails is negligible; they are 100 cm long.

Due to the specific screws required for BOAXEL rails, only anchors with a diameter of 6 mm are suitable. I am considering Fischer Duopower anchors, size 6 x 30. The manufacturer states that for gypsum block walls, a single anchor can handle a maximum load of 0.18 kN. I need 4 anchors per rail, so a total of 16 anchors.

In theory, the above should provide a load capacity of 2.88 kN or 293.6 kgf, the maximum combined load and the weight of the shelves is 243 kg, lower than the combined load allowed by anchors.

However, can I practically rely on these assumptions? I don't expect to put 24 kg on each shelf, and in general, even placing 20 kg on any shelf seems unlikely.

I also considered 6 x 50 anchors, but I'm concerned that due to the thin walls, I might end up damaging them when screwing in the screws, causing the anchor to expand too close to the surface on the other side and breaking the wall there (because of expansion tension).

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The limiting factor here is not the anchor but the gypsum wall. As can be seen in the Duopower data sheet the loads in other wall materials are higher than 0.18 kN. So using stronger anchors is not the answer. Instead I would suggest spreading the load to more anchors. Looking at the images in the manual for the rails there are additional holes in the top horizontal rail to be used for additional screws. There seem to be no extra holes in the vertical rails. If you think of the vertical rails as a lever and a single screw and anchor as the the fulcrum it should become obvious that the horizontal bar is not an optional component of the whole mounting frame but the most essential one. The highest force is exerted on the top and that is why you yield a higher amount of stability by adding one additional screws to the top than by adding the same screw to the bottom of the vertical frame.

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  • Unluckily no, I already mounted this system to some other wall (concrete) and, as I write, I counted only 4 screws per vertical rail for a 100 cm long rail, there are no more holes for this rail. You can also see it on page 18 of the 'Assembly instruction' you linked.
    – outlying
    Commented Jun 8, 2023 at 23:20
  • And the horizontals? It looks like only every third or fourth hole is used. It looks as if the verticals basically hang on that bar.
    – xenoson
    Commented Jun 9, 2023 at 16:11
  • for BOAXEL horizontals are not being used for carrying the load, they are only used to level all vertical rails, manual states that you should not hang the shelf only with horizontals anchored. You are not forced to use horizontals if you don't like them, because if you use them you won't be able to remove them after vertical rails are anchored. I used them on the other wall because they are helpful and I don't mind them - they ended up very high, around 220 cm above the floor, and covered with some bigger boxes, so I don't see them
    – outlying
    Commented Jun 9, 2023 at 18:40
  • There are additional holes in the horizontals, right?
    – xenoson
    Commented Jun 9, 2023 at 18:55
  • The description of all those BOAXELs states they are mainly meant to be mounted on back panels of cabinets. That would be another option. Attach a board or pole to the wall with enough screws. You could also drill additional holes through the verticals, but that could get messy and inaccurate without good equipment and experience.
    – xenoson
    Commented Jun 9, 2023 at 19:16

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