Damp penetration from Shower.

[RP66]

I have a 1930's semi, and in the bathroom has been installed a walk-in shower with tiled walls.
Unfortunately the rear of the shower is on a wall shared with a bedroom and I have noticed damp bubbling up the plaster, therefore assume that the water is penetrating the tiles through the grout, do I need to remove all the grout? Or is there another answer to this problem.

If it is remove the grout what is the easiest way, have tried to remove a small part and it took ages.

Thanks for any help.

 

[vinn]

When was the walk-in shower installed?
Is the wall in question a masonry wall or a stud wall?
Presumably the shower valve is on another wall?
A photo of the shower wall might help?

 

[RP66]

When was the walk-in shower installed? Not sure only moved in a couple of months ago.
Is the wall in question a masonry wall or a stud wall? A masonry wall.
Presumably the shower valve is on another wall? Yes
A photo of the shower wall might help?

 

[vinn]

It looks like a good installation - no obvious signs of water penetration.
Could you post a photo of the other side of the wall: the bubbling area? And a photo of the basin showing supplies and waste?
"Weak areas" of the installation might be (only possibilities) where the base meets the wall tile ie. the silicone caulk, the grout in the decorative strip, and the stile for the enclosure.