Do I need to retile the whole wall(s) in a shower enclosure?

I would strip the tiles and leave tiling to tilers and plumbing to plumbers. Yes dehumidifier v important

Hi, cracks in the tiles can be a few things.

They have not been stuck correctly and movement from the change of temperatures is causing them to crack ( take something light and tap on the tiles see if they sound hollow.

Do you know what surface he was tiling on when work was being carried out? Are you sure he prepared the area correcrly?

Lastly, what quality of tiles are they? Its rare but does happen poor quality tiles tend to have a abundance of issues arising with them.

In all likelihood, the reason why it's cracking is because the substrate (the surface or boards under tile) is not the correct one for tile.
Tiles by themselves are not strictly waterproof. Water WILL always get behind them via the grout. So, the substrate needs to be made out of the right boards and correctly tanked. Specifically how and what depends on the existing wall. You should get all tiles off, and get a bathroom fitter (not a plumber who dabbles in tiling) to prep the wall and tile it so that it's done properly from start to finish. I hope this helps. Tarik

Replacing the whole area would be best, I agree with a dehumidifier also but even after that I would suggest getting damp tested in the walls and if all is ok make sure the walls are flat for best results fitt cement boards where the shower will be also the right adhesives and grout are used and then that everywhere is correctly sealed after.

Why use a plumber to tile, its like asking a taxi driver to fly a plane..........

With what you have said it sounds like the wall will be damaged behind the tiles, which means the whole wall will need to be removed and start again, using a professional tiler.
Steve SDB Building and Maintenance, Tiling Specialist

1st up, I wonder if the issue is on the wall where your shower mixer is. If it is, then I'm 51% sure, there's a small leak coming from a shower pipe within the wall. To note, even if it was one drip every 24hrs (or even one drip a week!) in the end, that single drip of water will damage the wall.
I would remove the damaged tiles, then feel the wall for dampness. There also could be rising damp on that wall. But first, remove the shower panel on the tray, get a touch and see if you can spot any wet or dampish areas at the bottom of the wall. If the damage is underneath the shower mixer, then it's probably a nut behind the mixer that is the leaking issue It would depend on how bad the dampness before getting/hiring a dehumidifier. If its not that bad, just remove x amount of tiles, leave the bathroom rad on, and within about 7 days the wall should be dry. But it's an absolute must, to find/fix/repair that leak. Bottom line, rising damp or a 'very small' leak. (just re-tiling without finding the issue, is a waste of money, as the samething will happen again)

Yes you would need to solve the damp problem or the adhesive wont bond
Better to remove all and start again

Rip it out and start again sorry. You just don't no wat problems are behind the tiles.
It has to be done in green moisture board and full tanked with a mapi tanking system and then retilied

I would recommend ripping out all of the tiles in the showerarea, aswell as the plasterboard behind. The area should be reboarded with showerproof tile backerboards and tanked before re-tiling.