Hi. We are converting the downstairs laundry to a room that will have a shower and basin. There's no waterproofing in the existing laundry.

When we start demolition and constructing the new shower, do the entire walls and all the floor of the entire room need to be waterproofed. OR... is it just the 2 walls adjacent to the shower and the shower floor (ie extent of shower glass) that needs to be water proofed.

FYI. The existing laundry has entire room with tiled floors. We want to keep the majority of the existing tiles and rip up only under the proposed shower and waterproof that small location-dont know if that's permitted or not.

Thanks for your help.