Bathroom Refit Trade Sequence: Strip-Out, First Fix, Wet Areas and Decoration — Trade Coordination and Handovers

Quick Answer: A full bathroom refit runs across 6–8 trade stages, from strip-out to decoration. The critical path is: strip-out → structural repairs → first-fix plumbing and electrics → waterproofing → tiling → second-fix plumbing → second-fix electrics → decoration. Building Regulations Part P applies to electrical work in bathrooms; Part G applies to unvented hot water; bathroom zones (BS 7671 Section 701) govern electrical installation in wet areas.

Summary

A bathroom refit is the most common multi-trade domestic job in the UK. It looks straightforward but regularly goes wrong because trades are sequenced incorrectly or handover conditions between stages are not respected. The most common failure points are: tiling before waterproofing (leading to leaks into the floor or wall below), second-fix plumbing before tiling is complete (creating difficult cuts around fixed valves), and electrical second-fix before floor is finished (creating trip hazards for finishing trades).

This guide presents the canonical sequence for a full bathroom refit — replacing all sanitaryware, retiling, and upgrading the suite. Partial refits (suite swap only, retile only) can follow the relevant stages. En-suite installations in a new room follow the domestic extension trade sequence first (see domestic extension trade sequence) and then apply the bathroom sequence from Stage 3.

CDM 2015 applies where two or more contractors are involved. On a domestic bathroom refit where a plumber and an electrician are both engaged alongside the main contractor or client, CDM duties arise. In practice, most domestic bathroom jobs are managed by the main contractor or plumber as de facto Principal Contractor — a written Construction Phase Plan (even a brief one) is legally required.

Key Facts

• BS 7671:2018+A2:2022 Section 701 — electrical installation in bathrooms and shower rooms. Defines Zones 0, 1, and 2 with permitted IP ratings and circuit types. Zone 0 (inside bath/shower): only SELV circuits, IPX7 minimum. Zone 1 (above bath to 2.25m): shaver socket excluded, IPX4 minimum. Zone 2 (600mm beside bath/shower to 2.25m high): IPX4.
• Building Regulations Part P — electrical work in bathrooms is notifiable. Must be certified by a competent person (registered electrician) or notified to Building Control.
• Building Regulations Part G — sanitation and water efficiency. G3 covers unvented hot water cylinders (G3 competent person certificate required). G4 covers sanitary conveniences and bathrooms.
• Building Regulations Part F — ventilation. Bathrooms without openable windows require mechanical extract ventilation: minimum 15 l/s intermittent (or 8 l/s continuous) for bathrooms; 6 l/s for separate WCs.
• Waterproofing — not a Building Regulation requirement per se but is best practice and often a warranty condition. BS EN ISO 21674:2021 covers wet area waterproofing systems. Most tile adhesive manufacturers require tanking before tiling in shower areas.
• Tile adhesive coverage — minimum 65% contact for wall tiles, 85% for floor tiles (BS 5385-3:2014). Full bed coverage required for natural stone and large format tiles (>600×600mm).
• Minimum substrate drying time — new sand-cement render or plaster: 4 weeks per 10mm thickness. New plasterboard with moisture-resistant board: 24 hours before applying tanking.
• Shower tray installation — all shower trays must be fully bedded on a continuous mortar bed or purpose-made adjustable tray support. Rigid fixing prevents differential movement and seal failure.
• Pan connector — use a flexible pan connector (not rigid) for all toilet connections to allow micro-adjustment without breaking the pan.
• Silicone joints — movement joints in silicone (not grout) are mandatory at all internal corners, around sanitaryware perimeters, and at floor-to-wall junctions to BS 5385-1.
• Extractor fan — Part F requires humidistat-controlled extract in bathrooms. Timer overrun on both humidistat models is standard.
• Shaver socket — must be a BS EN 61558-2-5 compliant shaver supply unit (isolation transformer type). Permitted in Zone 2 and outside zones.
• Heated towel rail — electric heated towel rails in Zone 2 must be IPX4 and connected via a 3A fused spur outside the bathroom zones, switched locally or by a pull-cord.

Quick Reference Table

Detailed Guidance

The Trade Sequence

Stage 0 — Measure, Design, and Specification

Who: Plumber/main contractor, bathroom designer (if applicable), client.

Tasks:

• Measure the existing room precisely: floor area, ceiling height, door swing, window position, existing soil stack position.
• Confirm sanitaryware layout: minimum 700mm clear space in front of WC, minimum 1,000mm recommended. WC/basin spacing minimum 200mm edge-to-edge.
• Specify all products: suite, tiles (quantity + 15% waste), adhesive, grout, sealant, waterproofing system, extractor fan, towel rail.
• Order long-lead items (bespoke tiles, freestanding bath, brassware from Europe) before booking trades.
• Confirm electrical zones and specify luminaires with correct IP rating.
• Survey existing drainage: confirm soil stack connection point, inspection access, and location of waste pipes in ceiling below.

Handover to Stage 1: All materials on order. Sequence agreed. Trades booked in correct order with sufficient gaps between stages.

Stage 1 — Strip-Out

Who: Plumber or general builder.

Tasks:

• Isolate water supplies at local isolation valves or at the mains stopcock.
• Drain down relevant heating circuits if radiator or towel rail is being moved.
• Isolate electrics at consumer unit — lock off circuit and test with voltage indicator before cutting any wires.
• Remove all sanitaryware: WC (undo pan connector, remove cistern), basin (disconnect trap and supply pipes), bath or shower tray (disconnect waste and overflow).
• Remove old tiles (use SDS hammer drill with chisel bit, not SDS-only — shock damages substrate). Use face shield and ear protection.
• Inspect substrate after tile removal: assess condition of plasterboard, render, or masonry. Identify any damaged areas, mould, or delaminated material.
• Remove existing flooring: vinyl, tiles, or carpet. Inspect subfloor.
• Remove radiator and towel rail if being relocated or replaced.
• Remove old extractor fan.
• Disconnect and cap all existing plumbing connections.
• Remove all debris to skip/bags before next trade arrives.

Critical check: Once stripped, inspect: (1) any evidence of previous leaks in floor or walls; (2) condition of joists if ground floor is suspended timber; (3) presence of any hidden runs (asbestos insulation pipe lagging in pre-1985 properties — check before cutting).

Asbestos note: Artex ceilings, old floor tiles, pipe lagging, and some textured wall surfaces pre-2000 may contain asbestos. Do not disturb without an asbestos survey under Control of Asbestos Regulations 2012 if age and condition suggest risk.

See also: asbestos containing materials acm, bathroom floor prep

Stage 2 — Substrate Preparation and Structural Repairs

Who: Builder/plasterer, carpenter (if floor repair needed).

Tasks:

• Repair any damaged plasterboard or plaster substrate. In wet areas, replace standard plasterboard with moisture-resistant (MR) board (e.g., Gyproc Moisture Board) or tile backer board (Aquabord, HardieBacker, Wedi, etc.).
• For shower enclosures and wet rooms: install cement-based tile backer board over timber frame or masonry. Do not tile directly onto standard plasterboard in shower areas.
• Repair timber floor joists if damaged or deflection-prone. Bathroom floors must be rigid: maximum deflection L/360 of span for floor tiles per BS 5385-3. Typical fix is to double the joist or add noggins and an additional layer of 18mm WBP plywood.
• Refix any loose floorboards/ply. Countersink all screws flush.
• Ensure floor is level: acceptable tolerance for floor tiling is ±3mm under a 2m straight edge. Use flexible floor levelling compound where required.
• Commission any structural work (e.g., moving a stud wall) before services start.

Handover condition to Stage 3: Substrate sound, dry, and level. All MR board or tile backer board installed. No structural defects.

See also: drylining in wet areas, floor levelling, bathroom floor prep

Stage 3 — First Fix: Plumbing

Who: Plumber.

Tasks:

• Run new hot and cold supply pipework to all new sanitaryware positions (WC cistern, basin, bath, shower).
• Install new waste pipework to sink, bath, shower tray, and WC connection — confirm falls (minimum 1:40 for 32mm waste, minimum 1:80 for 100mm soil pipe under BS EN 12056-2).
• Install any new soil stack connections or stack extensions if relocating WC.
• Install underfloor heating manifold (if wet UFH is being added to bathroom).
• Install new radiator or heated towel rail pipework in first-fix position (cap off for pressure testing).
• Pressure test all water supply pipework to 1.5× working pressure for 1 hour (typically 10–15 bar). Test before any boarding covers pipes.
• Cap all pipes temporarily with fitting caps (not clips of rag).

Key rule: All plumbing runs in walls or under floors must be complete, pressure-tested, and signed off before tiling. Any future leak behind tiles = full re-tile job.

See also: waste pipes, sanitary pipework design, underfloor heating

Stage 4 — First Fix: Electrics

Who: Electrician.

Tasks:

• Run cabling for: ceiling light (IP65 in Zone 1), extractor fan (with humidistat), shaver socket (outside zones or Zone 2, never Zone 0 or 1), heated towel rail fused spur (outside zones), underfloor heating thermostat (outside zones or Zone 2 minimum IPX4), mirror with light and shaver socket (if wall-mounted, Zone 2 minimum).
• Install back boxes for all points.
• Install pull-cord switch if ceiling switch required (the only permitted switch within 60cm of bath/shower in standard installations).
• Confirm cable runs do not cross tile lines — mark out all box positions before tiling so tiler knows exact positions.
• Do NOT terminate or fit accessories at this stage.

Key rule: Confirm all zone positions with tiler before cables are routed behind tiles. The zone boundary is fixed by the bath/shower edge — measure carefully before burying cables.

See also: bathroom fan wiring, bathroom lighting, bathroom zones

Stage 5 — Waterproofing (Tanking)

Who: Tiler or waterproofing specialist.

Tasks:

• Apply waterproofing system to all wet areas: shower enclosure (walls floor to ceiling and minimum 500mm beyond shower area), bath surround (at least 200mm above bath rim and 100mm wide on adjacent walls).
• Approved systems: BAL Waterproofing Membrane, Mapelastic, Aquaflex, Wedi Board, or equivalent. Follow manufacturer technical data sheet (TDS) exactly — mixing ratios, coat thicknesses, drying times.
• Bed waterproof foam strips at all internal corners before applying liquid membrane (prevents cracking at joints).
• Allow full cure as per TDS (typically 12–24 hours between coats; 2 coats minimum on floors, 2 coats on walls).
• Seal all pipe penetrations through tanking layer with manufacturer's pipe boot/collar or flexible sealant.
• Wet room floors: apply proprietary wet room former (Wedi, Schluter Kerdi) with integrated fall or use screed former with pre-formed fall, overcoated with membrane.

Critical inspection point: Tanking is the most important quality gate in a bathroom refit. Inspect for pinholes, missed areas at corners, and coverage at penetrations BEFORE tiling covers it. A failed tanking system = tiles off, retank, retile.

See also: bathroom waterproofing tanking, wetroom construction, wet room installation guide

Stage 6 — Tiling: Floors and Walls

Who: Tiler.

Tasks:

• Set out layout: establish datum lines, centre lines, and tile break positions. Avoid cut tiles smaller than half-width at focal points.
• Fix floor tiles first (on fully cured tanking and substrate), then wall tiles. In wet rooms: floor tile then wall tile so wall tiles lap slightly over floor tiles at the perimeter.
• Use appropriate adhesive: flexible C2S2 classification minimum in wet rooms and shower areas (BS EN 12004:2017), S1 flexible minimum for wall tiles in wet areas.
• Bed large format tiles (>600×600mm) with full-coverage notched trowel application on both tile and substrate (double-buttering). Coverage minimum 85%.
• Leave adequate movement joints: perimeter joints (internal corners and floor-to-wall junction) must be silicone, not grout. Intermediate joints at 3–4.5m centres in large tiled areas.
• Grout walls and floor: use flexible/anti-mould grout in all wet areas. Epoxy grout for commercial-grade durability in showers (see epoxy grout guide).
• Do NOT fix sanitaryware, fittings, or accessories until tiling is complete and grout is fully cured.

Dependencies: Tanking fully cured. Floor substrate rigid and level. All back boxes confirmed in correct position.

See also: large format tiles, tile backer board guide, waterproofing, bathroom tiles guide

Stage 7 — Floor Finish (If Not Tiled)

Who: Floor layer.

Tasks (where non-tiled floor specified — e.g., luxury vinyl tile, vinyl sheet):

• Install 6mm flexible plywood over subfloor if required, fill all joints and screw heads with floor filler.
• Lay LVT or vinyl sheet per manufacturer instructions. Ensure substrate is clean, dry, and flat to ±2mm per 2m.
• Heat-weld vinyl seams in wet areas for a waterproof joint.

See also: lvt installation, vinyl sheet

Stage 8 — Second Fix: Plumbing

Who: Plumber.

Tasks:

• Install bath (set into position, fit waste and overflow, connect supply flexible tails, apply silicone to base perimeter where it meets tiled floor or panel).
• Install shower tray (fully bed on mortar or set on adjustable legs, connect waste to drainage, apply perimeter silicone — do NOT grout between tray and tiles).
• Install shower enclosure, glass screen, or wet room glass panel.
• Install shower valves, thermostatic cartridges, and handset/overhead rose.
• Fit basin on brackets or pedestal. Connect bottle trap and flexible supply connections.
• Install WC: connect pan to pan connector, fit cistern, connect water supply flexible hose, connect flush pipe/internal mechanism.
• Connect heated towel rail to pipework (or fill/bleed if electric).
• Fill and commission heating system if UFH or towel rail connected to heating circuit.
• Test all connections for leaks under live pressure. Leave 24 hours before inspection and sign-off.

Key rule: Apply sanitary-grade silicone sealant between ALL sanitaryware and tile surfaces (bath rim, shower tray perimeter, basin back to wall). Use a single continuous bead. No grout between bath and tiles — silicone only.

See also: bath installation, walk in shower installation, thermostatic mixing valves

Stage 9 — Second Fix: Electrics

Who: Electrician.

Tasks:

• Install ceiling light fitting (IP65 minimum in Zone 1).
• Install and connect extractor fan (humidistat setting: typically 70–75% RH to activate; overrun timer: 2–5 minutes after light switch off).
• Install shaver supply unit.
• Install heated towel rail fused connection unit (outside bathroom zones, 3A fused, switched or unswitched per specification).
• Install underfloor heating thermostat (outside zones, behind wall or outside door).
• Install mirror with integral shaver socket if specified (Zone 2 — confirm IP rating meets IPX4).
• Connect and test all circuits. Complete Minor Electrical Installation Works certificate or Electrical Installation Certificate.
• Notify Part P to Building Control or self-certify under competent person scheme.

See also: part p overview, bathroom lighting, bathroom extractor fan guide

Stage 10 — Accessories, Decoration, and Snagging

Who: Decorator, plumber, main contractor.

Tasks:

• Paint or decorate any non-tiled wall areas. Use moisture-resistant paint in bathroom environments. Apply after all trades have finished to avoid damage.
• Install mirror, toilet roll holder, towel hooks, robe hooks.
• Fit toilet seat (often supplied separately from pan).
• Fit bath panel (acrylic or tiled front panel).
• Apply final silicone bead to all perimeter joints. Tool neat.
• Snag: check all grout lines, tile alignment, silicone joints, tap operation, flush operation, waste flow, extraction, and lighting. Compile snag list and resolve before handover.

Handover to client:

• Test all connections in front of client.
• Demonstrate controls: shower thermostat, extractor fan humidistat, towel rail timer/thermostat, UFH thermostat.
• Issue electrical certificate, plumbing pressure test record.
• Provide manufacturer guarantees for sanitaryware, tiles, and brassware.

See also: interior emulsion, snagging list management

Frequently Asked Questions

Can I tile before the plumber has finished?

Only after first-fix plumbing is complete, pressure-tested, and the plumber has confirmed no further runs will be needed. You cannot tile and then modify pipework — every cut into a tiled wall is disruptive, expensive, and risks damaging tiles. Agree all plumbing positions before the tiler starts. Mark socket box and fitting positions with chalk before tiling begins.

Does electrical work in a bathroom always need notifying to Building Control?

All electrical work in a bathroom is notifiable under Building Regulations Part P unless it is a like-for-like replacement of a fitting (e.g., replacing a like-for-like ceiling light with the same rating). New circuits, new positions, additional circuits, and consumer unit work must be notified. The notifier can be a registered electrician self-certifying under a competent person scheme, or the client can notify Building Control directly.

How long does a full bathroom refit take?

A standard bathroom refit (strip, substrate repair, first-fix, waterproofing, tiling, second-fix) takes 5–10 working days for one team. The main variables are: tile drying and grout cure time (24–48 hours before walking on floors, 24 hours before sealing or contact with water), and plaster drying time if re-plastering is needed. A wet room or full luxury refit can take 2–3 weeks.

Should silicone go on before or after grouting?

After grouting. Grout all joints fully (including internal corners where the tiler may have initially grouted). Once cured, rake out the internal corner joints to 5–8mm depth, clean dry, and apply sanitary silicone in a single continuous bead. The grout underneath the silicone provides colour continuity and structural support. Never grout internal corners — they will crack as the building moves.

Can a bathroom be created in a room with no external window?

Yes, under Building Regulations Part F, a bathroom without a window can use mechanical extract ventilation (minimum 15 l/s for a bathroom, 6 l/s for a separate WC). The extractor must be humidistat-controlled and run for a minimum overrun period. The duct must terminate externally (not into a loft or void space) and follow minimum duct length and bend requirements to maintain extract rate.

Regulations & Standards

• BS 7671:2018+A2:2022 Section 701 — electrical installations in rooms containing a bath or shower. Zone definitions and IP rating requirements.

• Building Regulations Approved Document P — electrical safety in dwellings; notifiable work and competent person scheme.

• Building Regulations Approved Document G — sanitation, hot water, and water efficiency. G3 (unvented hot water), G4 (bathrooms).

• Building Regulations Approved Document F:2021 — ventilation; mechanical extract rates for bathrooms.

• BS EN 12004:2017 — adhesives for tiles. C1, C2, S1, S2 classification in wet areas.

• BS 5385-1:2018 — design and installation of ceramic tiles and mosaics on walls, including movement joint requirements.

• BS 5385-3:2014 — design and installation of floor tiles, including substrate deflection limits.

• BS EN ISO 21674:2021 — waterproofing systems for wet rooms (note: check current status; some manufacturers reference earlier ANSI or national standards).

• Control of Asbestos Regulations 2012 — survey requirements before disturbing suspected materials.

• CDM 2015 (Construction Design and Management Regulations) — applies where two or more contractors are engaged.

• Planning Portal: Bathrooms and Building Regulations — overview of which regulations apply.

• IET (Institution of Engineering and Technology): BS 7671 Guidance — wiring regulations in bathrooms.

• CIPHE (Chartered Institute of Plumbing and Heating Engineering) — plumbing installation standards.

• BAL Adhesives Technical Data Sheets — manufacturer guidance on tanking, adhesive, and grout specification for wet areas.

• HSE: Asbestos in Construction — survey and sampling requirements before strip-out.

• bathroom planning guide — layout, zone planning, and specification before work starts

• wetroom construction — full wet room construction guide

• bathroom waterproofing tanking — tanking systems for wet areas

• tile backer board guide — selecting the right substrate for wet area tiling

• bathroom zones — Zone 0, 1, 2 reference guide for electricians

• domestic extension trade sequence — full extension trade sequence (for en-suites in new extensions)

• part p notifications — Part P notifiable work guide

• asbestos containing materials acm — what to look for during bathroom strip-out