Renovating a bathroom step by step: the right order from planning to handover

The bathroom is the smallest room in the house, but it brings together the most sensitive trades: water supply, drainage, electrics, waterproofing and tiling. This guide puts the work in clear stages and links each stage to its detailed, sourced guide.

Stage 1: Planning

1. Draw a simple dimensioned plan: shower/bath, WC, basin, door, window/extract fan.
2. If moving the WC or drain, first confirm the required falls can be achieved to the connection point.
3. Mark the electrical zones from the shower position and place lights and sockets outside them. See bathroom electrics.
4. Choose materials early (tiles, sanitaryware, mixers) because their sizes affect the services.
5. Write a bill of quantities and specifications, and ask for detailed quotes. See the renovation checklist.

Stage 2: Strip-out and inspection

• Isolate water and electricity to the bathroom before starting.
• After strip-out, inspect: the concrete slab under the floor, signs of old damp, and the old pipes (especially galvanised steel). See rebar corrosion.
• Photograph everything you find; discoveries here can change the plan and the cost.

Stage 3: Hidden services

Water and drainage

• Choose the right pipe type for hot and cold lines. See pipe types.
• Keep to drainage falls and trap depths, and never remove venting.
• Fit a branch valve for the bathroom.
• Pressure-test the water supply and test the drainage before closing up.

Electrics

• Bathroom circuits are protected by a 30 mA RCD. See breakers.
• The water heater on a dedicated circuit, and lights and extract fans with an IP rating suited to the zone.
• Keep to standard wire colours. See wiring.

Stage 4: Floor and falls

• The shower floor needs falls towards the drain.
• Repair cracks and dips before waterproofing.

Stage 5: Waterproofing

• Use a liquid-applied membrane under the tiles complying with EN 14891, with reinforced corners and pipe outlets. See waterproofing under tiles.
• Flood test after drying and before tiling.

Stage 6: Tiling

• Tiles: for the bathroom floor prefer low-absorption tile with suitable slip resistance. See tile types and reading specifications.
• Adhesive: compatible with the membrane and suited to the tile type and size. See the adhesive guide.
• Coverage: 95% in wet areas and showers. See tile installation.
• Grout: CG2WA or epoxy for the shower. See the grout guide.
• Movement joints at corners and changes of plane are filled with mould-resistant sanitary silicone.

Work out quantities with the Binaaline tools.

Stage 7: Fixtures and finishing

• Install sanitaryware and mixers (a thermostatic mixer is preferred for the shower). See hot water safety.
• Install lights, extract fan, mirrors and accessories, avoiding piercing the membrane in the shower area where possible.

Stage 8: Handover

1. Open all taps and watch drainage and for leaks under the basin.
2. Pour water on the shower floor and check the falls and that no water ponds.
3. Press the RCD test button.
4. Tap the tiles gently to find hollow sounds. See tile problems.
5. Collect warranties, material data sheets and photos of hidden work.