What should a quote for a 5 m² bathroom renovation include?

Measure the room and the people using it

Start with a measured drawing showing the door swing, window, basin, WC, bath or shower, radiators and usable circulation. Record the finished positions, not just the present ones. A wall-hung WC can require a support frame and enclosure; a larger basin can reduce access. Ask the designer to test the layout with the actual product dimensions before ordering.

CEAPAT’s guidance on bathing treats assistance, transfers, supports and user capability as connected questions. A low shower tray alone does not make a bathroom accessible. If mobility is a priority, have the whole route, clearances and support locations assessed for the person who will use it. Keep that assessment separate from a sales label such as “adapted”.

Separate demolition from preparation

Removing tiles does not provide a ready substrate. Ask whether the quote includes removing loose backing, correcting levels, repairing damaged areas, protecting adjoining rooms and taking waste out of the building. Identify what inspection occurs after strip-out and before new surfaces conceal the work.

For waterproofing, request the proposed system, treated areas, junction details and the manufacturer’s installation requirements. The quotation should name who checks the substrate, drain connection and waterproofing before tiling. Tile grout or a visible bead of sealant should not be treated as the whole waterproofing design. Record the inspection and any agreed testing, rather than instructing the owner to perform improvised tests.

Make drainage, air and electricity part of the scope

Ask the plumber to confirm the drainage route, available levels, connections to the existing stack, shut-off arrangements and access for future maintenance. Moving a WC is a different proposition from replacing its pan. Investigate the connection before accepting a price that assumes a new route will fit.

CTE DB-HS addresses ventilation, water supply and drainage. Have the professional establish which requirements apply to this existing-building intervention and how the bathroom will work with the rest of the dwelling. An extractor connected to an unsuitable shared duct is not resolved by buying a more powerful fan. The electrician should assess the revised bath/shower layout under REBT ITC-BT-27, including equipment positions and protection; a screen does not automatically resolve electrical safety zones.

A budget with a visible boundary

Ask the bidder to confirm the tax treatment using AEAT’s renovation conditions; 10% is conditional, not a standard bathroom discount. Where an advertised package already includes supply and fitting, do not add the same installer’s labour a second time.

Check quantities rather than multiplying floor area

For this imaginary room, a 9 m perimeter × 2.4 m tiled height gives 21.6 m² of wall. Subtract a 0.8 × 2 m doorway and a 1 × 0.6 m window: 19.4 m² remains. Adding 5 m² of floor gives 24.4 m². A chosen 10% cutting allowance produces 26.84 m². At 1.44 m² per box, round up to 19 boxes, or 27.36 m².

That single-box calculation only works if one specified product is suitable for both surfaces. Normally floor and wall products, patterns and box sizes need separate take-offs. Niches, boxed services, large-format cuts and spare tiles can change the order. Ask whether the tiler charges for net area, openings, edges and difficult details, and agree who owns unused unopened boxes.

Price selections before they become variations

Give each fixture an identifiable model or a genuine supply allowance with its tax basis. State whether delivery, carrying upstairs, assembly, waste fittings, concealed frames and disposal are included. Decide who replaces a damaged owner-supplied item and who pays for a return visit if it arrives late.

If a €900 gross screen allowance is replaced with an agreed €1,200 gross screen, the increase is €300, provided fitting scope is unchanged. Using reserve leaves €752.70 unallocated; preserving the reserve raises funding to €12,229.70. The cost change is not €1,200 on top of an allowance you have already funded.

Agree a sequence with checks before concealment

1. Confirm layout, procedure and product availability before demolition.
2. Inspect the opened room and agree any priced repair before proceeding.
3. Complete service routes, backing and waterproofing with the specified checks.
4. Tile and fit products after required curing periods, following the system instructions.
5. Check drainage, taps, ventilation, safe operation and agreed documents with the contractor.

Request a programme showing the days when the household has no usable bathroom. A promise of a fixed short duration without allowance for product delivery, drying or discovered damage is weak planning. Arrange temporary use or accommodation explicitly; do not assume the room can be used halfway through every stage.

Close against the accepted scope

Inspect falls and water containment through the contractor’s agreed commissioning process; check opening clearances, accessible maintenance points, finish quality and missing parts. Photograph snags, identify responsibility and set dates in writing. Keep product instructions, invoices, test records and any required certificates together.

Consumer-law price and contract information gives a foundation for a clear agreement, but your checklist must describe this room. Record selections, accepted changes and actual payments in your project record. A bathroom budget is useful when it buys a complete, maintainable room and makes the unresolved items visible before the last invoice arrives.

Sources, date and scope

• Ministerio de Vivienda / Código Técnico de la Edificación — DB-HS Salubridad: HS3, HS4 y HS5
• BOE — Real Decreto 842/2002: REBT e ITC-BT-25/27
• Agencia Tributaria — IVA: obras de renovación o reparación de viviendas
• BOE — Real Decreto Legislativo 1/2007: artículos 60 y 60 bis
• CEAPAT / IMSERSO — Productos de apoyo para la autonomía personal: baño y ducha, pp24–27

Sources checked on 19 October 2026. Local procedures and examples concern the city of Madrid unless stated otherwise. IVA explanations concern the territory where that tax applies, rather than the separate tax systems of the Canary Islands, Ceuta or Melilla. Original worked calculations are teaching examples for the stated scope, not market averages or contractor offers.