What lies behind the wall tiles
A new bathroom is judged by the part you can no longer see once it is finished. Under the tiles of a walk-in shower there is a continuous waterproofing system: a membrane or a liquid resin applied over the whole floor of the wet zone, carried up the walls — that part is called an upstand — and bonded to the waste with a collar. Continuity is the important word. Waterproofing broken over two centimetres in a corner lets through as much water as no waterproofing at all.
Above that waterproofing come the falls. A shower floor is not flat: it slopes towards its outlet, enough for the water to leave on its own, little enough to stand on without thinking about it. That fall is formed in the screed, before the tiling, not made up with adhesive.
Then the substrates. In a wet room the partitions and the linings are moisture-resistant — you can tell them by their colour — and the framing is reinforced wherever something heavy will be fixed: a wall-hung unit, a basin full of water, a grab rail. Those reinforcements go in when the partition goes up. Afterwards, it has to be opened again.
The walk-in shower: what the floor has to give
A walk-in shower means that the tray, or the fall formed in the floor, sits down within the thickness of the floor instead of standing on top of it. So depth is needed below the tiles, and not every floor has it.
On a concrete slab it is generally possible: either the floor is dug out, or the finished level of the room is raised slightly. On a timber floor in a period Nice building it needs a closer look — the depth available between the joists is limited, and the waste has to find its fall to the existing stack without passing through a load-bearing joist.
When the depth is not there, two honest solutions remain: the ultra-slim tray, which sits almost flush with the floor and gives the same look without digging out, or a single step up, owned and drawn as such. What is not honest is to promise a walk-in shower in the quotation and find out on site that it cannot be done.
That is why we look at the floor, the stack and the depth available during the visit, before pricing anything.
Ventilation, the item everyone forgets
A bathroom rebuilt from scratch that turns black in the corners again after one winter does not have a paint problem: it has an air problem. A shower produces steam in quantity; if that steam does not get out, it settles on the coldest surface in the room and stays there.
So there are three things to check, and they cost almost nothing while the room is open: that the extract really works and not merely that it turns, that air can get in — a gap under the door is enough, but it has to be there — and that the weak points are dealt with, because a duct crossing an unheated space condenses inside.
On the French Riviera this item is readily underestimated, because the window gets opened. But in winter it stops being opened, and that is when the damp settles in. We renew the mechanical ventilation during the works, while the partitions are still open.
What drives the time, and what drives the budget
A bathroom is a short but dense job: strip-out, plumbing, electrics, partitions, waterproofing, tiling, fitting the equipment. Each stage waits for the one before. The only two items that really lengthen the calendar are the drying times — screed, waterproofing, adhesive, grout — and the lead times: a made-to-measure unit, a concealed tap or a limited-run wall tile is ordered on signature, not when it is due to be fitted.
On the budget, three decisions weigh more than the rest: whether or not to move the waste pipes — a water point that moves costs far more than a water point that stays — the format and the nature of the tiling, and the level of equipment, from exposed to concealed brassware. Each is priced separately in the quotation, so that you can choose before signing rather than in the middle of the works.
And if it is the only bathroom in the house, say so at the visit: the order of operations is not the same when a shower has to be usable again as early as possible.
