I need to mount IKEA Metod wall cabinets on a sound/thermoproofing layer that is itself glued on reinforced concrete walls. These cabinets are installed on a rail
The layer consists of 1cm of plaster and 6cm of high density fiber glass wool, the specs are here in French (should be the 10+60 variant). Unfortunately it does not seem to indicate the plaster wall maximum load as far as I can see (probably because you are not supposed to mount stuff on it!) Behind it are 20cm of reinforced concrete.
I did not expect that that layer would be that thick and am having now doubts on how to best proceed. The person from the construction company recommended to use cavity dowels, but I am doubtful.
The specs of the cavity dowels I have indicate 20kg of load bearing capacity. A 60cm wide wall mounted cabinet weights about 20kg, and maybe 50kg fully loaded. It seems that I would need to put in quite a few screws to make this work (especially assuming some safety margin), and I suspect this will compromise the structure of the plaster wall.
The other option is to drill into the concrete, but given the lever forces in play here the required screw size would be quite big.
What do you recommend?