To tank or not to tank?

[Old Salt]

1960’s bungalow bathroom refurbishment replacing shower enclosure and sanitary ware. Walls are block and skim so do I need to tank the walls using backer boards, waterproof membrane or some other form of waterproofer? Finish will be ceramic tile. It looks as if the existing shower is not tanked but I haven’t stripped the tiles off the actual shower yet.

Thanks in advance for any helpful comments.

 

[Madrab]

I would always tank regardless. A liquid membrane would do the job, seal any/all joints/corners etc, either that or if the skim is in top condition then use a paint on tanking slurry.