Day 1-2: strip out and first fix
The first stage is stripping the existing bathroom back to the structure, removing old sanitaryware, tiling and, where needed, floor boarding to expose the joists or slab beneath. First-fix plumbing and electrics happen alongside this, running new pipework for the shower valve and any additional outlets, and cabling for lighting, extraction and underfloor heating if specified.
On a suspended timber floor this stage also includes any structural preparation identified at survey, addressing deflection, or adjusting joists ahead of the deck former going in, which can add a day if the floor needs more than routine work.
Day 2-3: floor preparation and deck former or screed
With first fix complete, the floor build-up goes in, either a deck former system on timber joists or a screed fall on a concrete slab, along with the drain body itself. This stage needs to be done accurately, since it determines the fall the whole room will have permanently, and it needs to be fully set or cured before waterproofing can begin.
This is one of the stages that genuinely can't be rushed. A screed, in particular, needs adequate time to cure before membrane goes over it, and pushing ahead too early is one of the more common causes of later problems.
Day 3-5: tanking, curing and flood testing
Waterproofing membrane goes onto the floor and walls in this stage, with reinforcing tape at all corners, joints and penetrations. Depending on the product, this typically needs at least 24 hours between coats and further time to cure fully before a flood test can be carried out safely.
A flood test, filling the floor to a shallow depth and leaving it for around 24 hours to check for any drop in level, adds a further day but is one of the most valuable checkpoints in the whole build, catching any issue with the membrane or drain seal before tiling covers it up.
Day 5-8: tiling
Once the flood test has passed, tiling begins, generally starting with the walls before the floor, or in some sequences the floor first depending on the fitter's method and the drain type. Large-format tiles take longer to lay accurately, particularly around a linear drain fall, and any bespoke cutting around fittings, niches or a glass screen fixing adds time here too.
Grout then needs its own curing time before the room can be used, typically at least 24 hours, sometimes longer for wider grout joints or certain grout types, so this isn't a stage to compress even when the rest of the project is running to schedule.
Day 8-10: second fix and finishing
The final stage covers fitting the shower screen if specified, second-fix plumbing to connect the shower valve and any basin or WC, second-fix electrics for lighting, extraction fan and any heated elements, sealant around junctions, and a final clean. This stage also includes commissioning any underfloor heating and testing extraction is working correctly.
A full wet room, including a WC and basin alongside the shower area, will sit towards the higher end of this range, while a simple en-suite shower-only conversion can come in closer to a week overall.
What causes overruns and how to avoid them
The most common cause of delay is discovering an unexpected floor or structural issue once boards are lifted, rot, inadequate joist depth or an awkward existing waste run, which is exactly why a thorough survey before quoting matters so much. The second most common cause is rushing curing times for screed, membrane or grout to hit a deadline, which risks the very problems tanking is meant to prevent.
Supply delays on a specific tile, drain or fitting can also add time if a bespoke item is chosen, so ordering materials as early as possible in the process, ideally confirmed at the design and quote stage, helps keep the programme on track. A written schedule setting out each stage, agreed before work starts, gives you a clear benchmark to check progress against as the job proceeds.