Bathroom renovation guide: sequence, waterproofing and common mistakes

The bathroom is the most expensive room per square metre and the least forgiving. Every job is buried under the next layer; a waterproofing fault beneath the tiles comes back years later as a leak into the flat below. This guide sets out the correct order and the critical decisions.

Where does a bathroom renovation start?

With the layout. Where will the WC, basin, shower and washing machine go? That decision determines the pipe runs, drain position and tiling plan. Changing the layout after the strip-out has begun means re-running the plumbing.

The correct order

1. Strip-out: tiles, sanitaryware, units and where necessary screed are removed.
2. Plumbing: clean and waste lines routed to the new layout; pressure tested.
3. Electrics: lighting, sockets, water heater and ventilation circuits.
4. Plaster and screed: walls levelled; falls formed in the shower area.
5. Waterproofing: liquid membrane on floor and wall bases, tape at corners; left to cure.
6. Tiling: walls first, then the floor.
7. Sanitaryware and tap installation
8. Units, mirror and accessories
9. Silicone and cleaning

Skipping the waterproofing step, or tiling before it has cured, is the most common and most expensive mistake.

Why waterproofing is non-negotiable

Tiles and grout let water through. Without a membrane beneath, water reaches the screed, then the slab, then the flat below. Waterproofing must cover the entire floor, the walls around the shower and every corner and drain detail. For more, see external and waterproof insulation.

Wall-hung WC and concealed cistern

A wall-hung WC leaves the floor clear, which helps with cleaning and appearance. The concealed cistern sits inside the wall, so it must be planned at the plumbing stage and its supporting frame fixed correctly. The access panel must remain reachable.

Why ventilation matters

In a bathroom without a window, mechanical ventilation prevents moisture build-up and mould. The circuit should be run at the electrical stage and the outlet connected to the building’s ventilation duct or to outside. Without ventilation, even the best waterproofing cannot fully prevent mould.

Choosing materials

• Tiles: slip resistance on the floor, easy cleaning on walls; large formats demand a level substrate
• Sanitaryware: water-saving cistern, easy-clean surfaces
• Taps: thermostatic or single-lever; cartridge quality determines lifespan
• Units: moisture-resistant carcass and doors (made-to-measure furniture)
• Lighting: moisture-rated fittings, shadow-free light around the mirror

The most common mistakes

• Floors closed up without waterproofing, or before it has cured
• Insufficient fall to the drain (standing water)
• Tiling before the plumbing has been pressure tested
• No ventilation planned
• Changing the layout after the strip-out
• Standard, non-moisture-resistant unit materials

What determines the cost?

Bathroom size, whether the plumbing is renewed, layout changes, tile and sanitaryware grade, and special details such as concealed cisterns and walk-in showers. An itemised written quote makes comparison meaningful.

Demgirişim delivers bathroom renovations including plumbing, waterproofing and tiling with a single team, treating waterproofing and pressure testing as standard steps.

Frequently asked questions