Six square metres, seven trades, thirteen steps. What it really takes.
Times and budgets are indicative, for a confident DIYer, surprises excluded.
A bathroom is the smallest room in the home and the job that packs in the most trades. Across four to six square metres: demolition, plumbing, electrics, masonry, waterproofing, tiling, fitting out. Each trade waits for the one before it to finish — and above all, to dry.
It is the drying that sets the calendar, not your energy. A levelling compound can be covered after 24 to 48 hours, a liquid waterproofing membrane needs two coats with a wait between them, the adhesive hardens for a day before grouting, and the grout waits again before the first shower.
Then there are the lead times: a made-to-measure vanity unit or large-format tiles are ordered weeks ahead, and the job stops at the first missing item. For all that time the house has no bathroom — and that constraint is what decides most people.
Estimated time 0.5 – 1 days
Survey the room to the centimetre, bulkheads included, then place every fixture with its real clearances: a shower door has to open, a wall-hung WC swallows 20 cm. Order everything before you break anything, with 10 % extra tiles.
What goes wrong — Ordering the tiles after the demolition. Six weeks of lead time, with the room stripped bare.
Estimated time 0.5 days
Close the main stopcock, drain down, switch the circuit off at the consumer unit and check there is no voltage. Find where the waste stack runs: it decides what you are allowed to move. Protect the hallway — tile dust travels.
What goes wrong — Switching off the lighting but not the sockets. One blow of the chisel into a live conduit takes out the whole flat.
Estimated time 1.5 – 3 days
Sanitaryware, units, wall tiles, then the floor tiles. Wall tiles bonded onto plaster come away with the plaster: plan on rebuilding the walls, not just stripping them. The least technical step, and by far the noisiest.
What goes wrong — Pulling off the wall tiles and finding a 5 cm plaster partition behind. It has to be rebuilt in full before you can tile again.
Estimated time 0.5 – 1 days
A 5 m² bathroom easily produces a tonne of rubble: in 25 kg bags that is forty trips up and down, and a recycling centre will not take an unlimited volume. Check the rules of the copropriété (co-owned building) before you use the lift.
What goes wrong — Loading the lift beyond its rated capacity. The repair and the downtime are billed to the owner concerned.
Estimated time 1.5 – 3 days
Supply pipes first: press-fitted multilayer, run in conduit, with outlets positioned to the millimetre against the tiling to come. Wastes next, with a steady fall all the way to the stack. Pressure-test before you close anything up, and let it hold for several hours.
What goes wrong — A shower waste with too little fall. The water sits there, and the repair means lifting the tray and the tiling again.
Estimated time 1 – 2 days
A bathroom is divided into zones by NF C 15-100 (the French electrical standard), and each zone allows or forbids a type of equipment. On top of that come 30 mA residual current protection and local supplementary bonding. Here the rule is not up for discussion.
What goes wrong — A socket set too close to the shower. Non-compliant, invisible once tiled over, discovered at the first inspection.
Estimated time 1 – 2 days
Walls that will get wet are rebuilt in moisture-resistant boards on a metal frame. The frame for a wall-hung WC is fixed to the floor and to a load-bearing wall, never to the partition alone. Everything has to be plumb: tiling corrects nothing, it reveals everything.
What goes wrong — A WC frame fixed to a lightweight partition. It shifts within months and the tiled boxing has to be opened up again.
Estimated time 0.5 – 1 days
A bathroom floor has to be flat, clean and dry. Depending on the substrate, that means anything from a self-levelling compound to a mortar fall formed for a walk-in shower. Primer is not an option: without it the levelling compound blisters.
What goes wrong — Levelling over a dusty substrate. The floor sounds hollow six months later and the tiles crack.
Estimated time 0.5 – 1 days
Tiles are not waterproof: the grout lets moisture through. It is the layer underneath — two coats, corner tapes, collars at every penetration — that protects the structure. The only completely invisible step, and the only one whose failure is paid for at the neighbour's below.
What goes wrong — Leaving out the corner tape between floor and wall. The water goes through exactly there, and the leak appears on the ceiling downstairs.
Estimated time 3 – 5 days
Start from a drawn setting-out: where the courses begin, where the cuts fall, how the wall lines up with the floor. Back-buttering for large formats, levelling clips, a level check every two tiles. This is the longest step.
What goes wrong — Starting without a marked starting line. The last row finishes as a two-centimetre wedge, visible from the doorway.
Estimated time 0.5 – 1 days
Grout with a float, sponge off before it hardens, then sanitary silicone in every internal angle: angles are never filled with cement grout, they move. Then you wait — no water until the manufacturer's time has passed.
What goes wrong — Cleaning the grout too late. The cement haze then only comes off with acid, which attacks fresh grout.
Estimated time 1.5 – 3 days
Vanity unit, WC, shower tray, mixers, shower screen. Every hole you drill goes through a surface you have just tiled, and therefore through the waterproofing: the right bits, slow speed, silicone in each hole before the wall plug.
What goes wrong — Drilling wall tiles on hammer setting. The tile shatters, and replacing it means breaking the tiles around it.
Estimated time 0.5 – 1 days
Without extraction, a new bathroom goes mouldy in one winter. Check the flow rate of the mechanical ventilation, paint the ceiling with a paint made for damp rooms, refit the accessories. Finish with a full water test, then look at the ceiling below the next morning.
What goes wrong — Blocking the air vent while redoing the ceiling. The grout darkens and the new tiling stains within months.
Range excl. VAT — VAT varies with the type of work
Indicative range, not contractually binding.
This estimate is not a quote: the final price is set with you, after a site visit.
On your own, thirteen to twenty-four days of actual work, spread over six to ten real weeks: drying and delivery times impose pauses that nothing shortens. A team running the trades back to back changes the calendar, not the number of hours.
As long as you stay inside the flat, without touching load-bearing walls or shared stacks, no planning formality is needed. As soon as you alter a shared waste pipe or the façade, it goes through the copropriété and, for the façade, through a déclaration préalable (prior works declaration). If in doubt, check with the mairie (town hall).
Technically yes, if the old tiling is perfectly sound, degreased and primed. But you lose height, the thresholds change, and you can no longer put proper waterproofing underneath. In a bathroom, that is rarely the right call.
Strip out, clear the rubble, plumbing, electrics, partitions, floor preparation, waterproofing, tiling, grouting, fixtures, ventilation, finishing. This is not a matter of taste: each step closes the previous one for good.
What decides is the distance to the waste stack and the fall available. A few dozen centimetres often works; changing wall means a study, sometimes a macerator, sometimes a no. Ask the question before you draw a layout.
Twelve steps, several of which the standard will not let you sign off yourself.
12 steps · 12 – 23 days
What you can see takes two days. What is inside the wall decides everything.
12 steps · 6 – 14 days
Screed, tiles, wood: what it really takes, step by step.
12 steps · 8 – 15 days
