Tiling or Plumbing -which comes first?!

[Im a BusyBee]

We are refurbishing and moving round utility and cloakrooms. The shower base instructions are that the walls must be tiled before putting tray in (obviously only a row or 2 of tiles on the area that the tray fixes to would suffice for this purpose initially). Im not sure whether all the tiling should be totally completed then the plumbing be carried out or whether a basic amount of tiling (as above) then get plumber to finish his work and finish with completion of tiling? What is the correct order please?!

[buildersmate]

Tiling is a finishing trade so goes towards the end. On what basis the instructions on the tray say that tiling around it must be done first, I don't know, but sounds odd to me. This is because you want to seal the TRAY well into the wall corner, then the tiling comes out over the edge of the tray, meaning that water drips off the bottom of the tile onto the tray (and into it). Silicon sealant sits in the HORIZONTAL gap between tile bottom and tray top. If you do it the way the instructions suggest, there is much more potential for water penetration down between tray of tile front face - and the sealant is attempting to seal a VERTICAL gap.
However the superstructure of a shower is fitted onto the base/walls after tiling (because you want tiling behind the vertical fixing bars).

[Im a BusyBee]

thanks so much for your reply buildersmate (i hoped you'd be around to give another excellent answer). you confirmed my thoughts but theres a bit more to it than that......not just the shower but going on from there ie toilet, washbasin etc would all of the plumbing for these be finished BEFORE tiling the walls?? Or as the showerbase instructions do state tiles need to be on wall before installation should i get the tiler to complete tiling altogether then get plumber in to run pipes round to cistern, wash basin etc??

[legend006]

The walls can be tiled to the base like bm says .
but the rough plumbing can be insitu.
as a shower only uses a cols supply normally a length of pipe from the wall then tile round it and to the base
the plumber can connect the shower at a later stage and the electrics can be roughed in place too.
Like on a building site .

[gasman]

The first fix plumbing should be done before any tiling This involves runing hot & cold pipes to the location of the Shower, Sink, Bath & WC + the installation of the Bath & shower tray and waste pipes. Then you can tile all the walls and down to the bath and shower tray and finaly start to 2nd Fix plumb ie. install the WC, Sink and shower including the cubical or screen and then apply sealant to the shower tray, bath and sink at the wall junction. "TIP" fill bath full of water before sealing and leave full for 24hrs.

[buildersmate]

It's worth explaining to the punters why, gasman. It's because the weight of the water pulls the bath downwards a bit and puts undue pressure on the silicon joint, tending to pull it apart.
If you fill the bath with water first, the silicon joint is formed in a position of maximum gap. The silicon is then a lot happier being under a little compression when there's no water in it.