We have a partition wall against which the over-the-bath shower head was mounted. It was broken when we bought the house.
It’s obvoius, even to me, that there’s a void behind the wall.
I remember something like a miniature car jack in shape, which is related to a rawl plug (?). The idea was that you inserted this thing into a hole in the wall, and screwed it tight. As you screwed it - the screw must have been attached to the end of the thing - the equivalent to the rawl plug, which is made of metal, folded outwards and eventually lay flush with the interior of the wall.
I hope that’s clear. If it isn’t, I happen to know that @DrMarkH recently replenished his cellars and is awash with vermut and pastis.
My problem is that I don’t know what it’s called in English, let alone French.
If you do use these, whatever you do don’t use an electric screwdriver to tighten them, do it by hand. If you use an electric screwdriver, it’s easy to snap the head off them.
Also make sure you use the special tool that collapses the cheville once in place. It look a bit like pliars and is included if you buy a kit.(pince de pose)
There are also sprung toggles with a half-round section which lays in line with the bolt when pushed through the hole, then pivots on the nut to 90 degrees to the bolt when through the hole. They are better at spreading the load, but can only be used once.
Weldom - and our friend - came up trumps. Madame needed to choose a doormat [insert your own joke here] and our friend took great delight in suggesting she do that while he and I go to see Molly.
I got the whole kit and caboodle.
Unfortunately, after assembling two IKEA beds, I had no enthusiasm for tackling the shower, so that’s for tomorrow, after our local vigneronne’s open day.