For various reasons we've ended up with a changed plan on an ancillary (not main bathroom) shower and it is to be a h&c direct mains feed to a bar shower fitting. The plumber has managed to get a couple of feed pipes to service this by reaching through a stud void but there's no stud or noggin to support the pipework immediately behind where the shower bar will go and no easy way of adding one. That means the pipes are a little floppy in the plasterboard holes.  He suggested getting the tiler to ensure tight holes in the tiles to secure the pipes in place but that sounds a bit risky to me and not sure what the tiler will make of it. Looking around there seem to be various 'behind tile' bar shower brackets but does anyone know if they are simply that - because when I look online everyone seems to still be fixing them to studs. or fitting pre plasterboarding. Are there ones with just a 'behind tile' thin faceplate that can be plugged and screwed to the plbd and do a better job of holding those pipes? 

I must be missing something but I would remove a section of plasterboard and add noggins/pipe brackets. Also add timber to support the cut edges of the plasterboard if you can't remove a whole panel.

Stop messing about, you cocked up, so just fix it. 

Chop into the back wall and remove a 600 square of plasterboard, fix a noggin then shower plate then patch up wall and fill. 

You just need to close your eyes and do it. 

Hanging a valve in tight fit tile holes is just asking for broken tiles and having to do it again.

Thanks all, yeh it's just a bit more complicated because of the position of an adjacent svp with an aav (and the plasterboard was opened up as far as seemed poss to get to where we are) but maybe it needs a bigger panel removed and some flat metal strapping for the shower plate or something in lieu of noggins if they can't be fitted easily. The main thing is that the solution suggested to me by the plumber is a no no and it's good to be able to double check that!

Photo?

Thanks Temp will post a photo if unable to solve once I open up - at the moment it is just a pic of two loose pipes sticking out the wall.

There is this type often mentioned, but it usually assumes there is something solid behind to screw into, e.g. a noggin.

 

You could try this with the rawl plugs just fixing into holes in the tiles.  As long as they are not too close to a tile edge and you don't swing on the bar mixer like a gorilla it might work.

 

But fitting a noggin behind is what is really needed.

 

https://ukbathroomguru.com/fitting-a-bar-mixer-shower-with-a-simple-kit/

Thanks Dave - a useful reminder about squareness there too as I can imagine how easily the bar could end up a bit squinty if any movement and then be quite noticeable in the riser pipe. I think I am going to have to open up but keep seeing plates like the one here https://www.ebay.co.uk/str/plumbersdepotshop which says 

• Unlike other fixing brackets, the PL8 requires no depth planning as it can work with any thickness of tile

Those look neat.

 

Flat plate thin enough to fit behind tile in the adhesive.

 

Compression fitting to grab copper pipe as it comes through the wall.

 

Your need a shower bar that could compression into the protruding ends of the copper pipe and big rough to hide the clearance booked for the nuts on that plate and you're good.

 

Glue it to the pb with some cartridge type adhesive. Prime the other side of it with something that tule adhesive can stick to. Or goo the tile to it using some cartridge type adhesive.

 

Only as strong as the plasterboard tile sandwich. That's probably pretty good if you're using big porcelain tiles etc. Could you rip a tile off using a bar mix as a lever? No? Good.

 

my wall mounted sink tap is essentially glued into brick before plasterboard using a polyester resin cocoon to tie it to resin fix screws that all wanted to go into frogs or mortar lines etc. Works fine.