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).