Bath to shower, step by step

What is checked during the survey (step 1)?

We look at the bath and the wall behind it, the floor construction, where the waste currently runs and how it reaches the soil stack, the position of the window and door, and the electrical points in the room. We measure the depth available below floor level for a shower trap and the fall of the waste.

We also ask about use: who will shower there, whether anyone has limited mobility, whether the property is let. These answers change the recommendation as much as the measurements do.

Step 2: which decisions do you need to make before work starts?

• Floor-level or low tray. Based on the survey, we explain whether a flush floor is feasible.
• Drain type and position. Linear along a wall or a point drain.
• Screen. Fixed panel, sliding or hinged door.
• Shower set. Concealed or exposed mixer, rain head, hand shower.
• Niche and accessories. Position and size of any niche, grab rail or seat.
• Finish. Tiles matching the room, a contrasting feature wall, or a seamless coating.
• Whole room or shower only. Whether the rest of the bathroom is renovated at the same time.

Concealed valve bodies, niches and grab-rail backing must be decided now, because they are built into the wall before it is closed.

Step 3: is there paperwork with the town hall or the community?

In Andalusia, the regional planning law (Ley 7/2021, known as LISTA) allows many minor works that do not need an architect’s project to be carried out under a declaración responsable, a sworn notice that the owner files with the ayuntamiento before starting, instead of a full licence. Each town hall publishes its own forms and may ask for a description and a budget of the works.

Whether your specific conversion is covered, and what the town hall asks for, has to be checked with the municipality (to be verified for each town). Separately, Spain’s Horizontal Property Act requires owners in a building to notify the community’s representative before works in their unit. The filing and the notification are the owner’s responsibility; we tell you what the job involves so you can describe it accurately.

Step 4: what happens during strip-out?

Water to the bathroom is isolated. The bath is disconnected and removed, then the tiles and render behind it and, if the floor is to be redone, the floor tiles and part of the screed. Debris is bagged and taken out along the route agreed with the community. At this point the old waste and supply pipes are exposed and we can confirm their condition.

Occasionally something unexpected appears, such as a corroded pipe or an old cistern made of asbestos cement. Anything unexpected is shown to you with photos before we proceed. Asbestos removal is a job for a registered specialist; see retiradauralitamalaga.eu.

Step 5: how are the waste and supply rebuilt?

The new waste runs from the shower drain to the soil stack with a continuous fall. Supply pipes are rerouted to the new mixer position, and the concealed valve body, if there is one, is fixed at its final depth so it matches the finished wall. Our authorised partner installers move or add electrical points according to the zones that ITC-BT-27 of Spain’s low-voltage electrical regulation sets around a shower.

Before anything is covered, the new pipework is pressure-tested. This is also the moment to confirm the final height of the mixer and the position of the niche, because both are fixed into the wall from here on.

Step 6: how is the shower floor formed and waterproofed?

For a floor-level shower, the screed is laid with a fall towards the drain. For a tray, the base is levelled to support it fully. The walls are rendered or boarded flat. Then the membrane goes on the floor and walls of the shower area, with reinforced corners, a sealed flange at the drain and sleeves around each pipe. The waterproofing guide describes this stage in detail.

Step 7: tiling or seamless finish, then fitting

Once the membrane has been checked, the finish goes on: tiles set out to align with the niche and the rest of the room, or several coats of a seamless system. Grout and movement joints follow. Then the shower set, screen, any grab rails and accessories are fitted, and the bathroom is cleaned.

Each finish needs its own curing time before water is allowed on it, and the screen is fixed only once the surfaces have set. The silicone at the junctions also needs to cure before the first shower. This is the stage where owners are most tempted to rush, and where patience matters most: a shower used too early can crack fresh grout or lift a seal that has not bonded yet. We tell you when the room is ready and leave written care notes for the finish you chose.

Step 8: what should you check at handover?

• Run the shower for a few minutes: water should drain without pooling and stay inside the screen.
• Look at the floor outside the shower: it should be dry.
• Check that the mixer is at a comfortable height and the temperature control works.
• Ask for the care instructions for the finish, the screen and the silicone.

If you are still deciding between options, see bath-to-shower conversions, walk-in showers and bath or shower.

Official sources

• Ley 7/2021 de impulso para la sostenibilidad del territorio de Andalucía (LISTA) – BOE
• Example municipal declaración responsable form for minor works under LISTA (Vera town hall)
• Ley 49/1960 de Propiedad Horizontal, art. 7.1 – BOE consolidated text
• REBT, Real Decreto 842/2002 (ITC-BT-27, rooms with a bath or shower) – BOE consolidated text