Does the shower area need tanking before tiling?

There is no regulation how a shower should be done. 1 shower walls must be fitted with Hardy backer waterproof boards before tiling, No plaster board! Powder adhesive to be used for the wall tiling

Depends on what walls you have in the shower area. If its just normal plasterboard, you may want to tank up. However tanking is only good if done correctly with using waterproof tanking tape especially where walls meet each other and where wall meets the floor, along with tanking solution. These areas are likely to crack and expand. Tanking is a last level of defence against moisture penetration A good Tiller and Silicone will ensure a everlasting water and moisture barrier.

Tile backer board is in most cases is a non necessary expense. It suggests water is getting past tiles /grout / silicone. Backer board doesn’t solve an existing problem. It just protects itself from getting wet

No plasterboard on the walls, even if it is moisture resistant. Wedi boards or Hardie Becker and waterproof matting over, glued with adhesive powder. Then fit the tray and apply silicone between tray and matting, tile over the tray, then grout and silicone. No leak anymore. It is expensive than just cheap plasterboard, but it is worth. Thanks