Bathroom Refurbishment in London: A Full Planning and Specification Guide

The most important stage of a bathroom refurbishment is the layout planning stage — and this is also the stage that most homeowners rush. Once tiles are on walls and the suite is installed, changing a layout is extremely expensive.

Key layout considerations:

Drainage runs: every sanitary fixture (WC, bath, shower, basin) must drain to the soil and vent stack (for WC waste) or to the drainage system (for bath, shower, and basin waste). Waste runs must fall at the correct gradient (minimum 1:40 for branch drains). Where a new en-suite or WC is being added away from the existing stack, the drainage run must be checked for achievable gradient and connection point. Macerator/pump systems (Saniflo-type) are an alternative where gravity drainage is not achievable, but they require a dedicated electrical supply and regular maintenance.

Zone positioning: electrical zones around baths and showers are strictly defined in BS 7671 (the Wiring Regulations). Zone 0 is inside the bath or shower tray; Zone 1 is directly above (up to 2.25m). Electrical equipment — lights, extractor fans, shaver sockets — must be rated for the relevant zone. All electrical work in bathrooms requires Part P compliance.

Wet room vs traditional layout: a wet room (a fully tiled room with a floor drain and no shower tray or enclosure) is popular for accessibility and for creating a high-specification feel. A wet room requires a properly sloped floor drain installed before the floor screed, and a full tanking system applied to the floor and walls before tiling. A traditional layout (shower tray with enclosure or bath with screen) is generally more forgiving of less-than-perfect waterproofing. Both can work well if detailed correctly.

Accessibility: future-proofing for accessibility — wider door openings (minimum 800mm clear), a level-access shower, and grab rail provision — is worth considering at refurbishment stage even if not immediately needed.

Water ingress through bathroom walls and floors is one of the most expensive problems in residential property. A properly waterproofed bathroom should not leak — but many installations in London homes (particularly those refurbished more than 10 years ago) rely on grout and silicone alone as the waterproofing layer, rather than a true tanking system.

Tanking systems: a tanking system is a waterproof membrane applied to the substrate (floor, walls) before tiling. Products include: brush-applied liquid waterproofing systems (such as Mapelastic, BAL Waterproofing Membrane, or Mapei products); bonded sheet waterproofing membranes (such as Schluter Kerdi-Board or similar); and tile backer boards with integral waterproofing. A properly applied tanking system makes the tiled surface watertight independent of the grout and silicone — grout and silicone are not waterproof and will fail over time.

Where tanking is essential: the floor of any wet room or shower area; the walls within the shower enclosure to at least 1.8m height; the walls around a built-in bath at the bath rim level; and any wall or floor area that will receive regular wetting.

Common failure modes: incomplete tanking with gaps at corners (the most common failure point — corners between wall and floor, between two walls, and around pipe penetrations); insufficient waterproof coverage at the bath rim; and tiling directly onto plasterboard without a waterproof membrane (plasterboard is not waterproof and will swell and crumble on prolonged wetting).

Tanking should be inspected before tiling: your contractor should allow you (or a site manager) to inspect the tanking before tiles are applied. Once tiled over, a tanking failure is invisible until the damage is already done.

Bathrooms without openable external windows must have mechanical extract ventilation. Building Regulations Part F requires:

Minimum ventilation rate: 15 litres per second (l/s) for a bathroom; 6 l/s for a separate WC. This is the continuous ventilation rate requirement.

Overrun timer: the extractor fan must have an overrun timer to continue running for at least 15 minutes after the bathroom is vacated.

Wiring and switching: extractor fans in bathrooms must be wired appropriately for the electrical zone they are in. A fan in Zone 1 (directly above the bath or shower) must be rated for that zone. Most fans are positioned in Zone 2 or beyond, where standard IP44-rated fans are acceptable.

Humidity-controlled fans: for best performance and compliance, a humidity-controlled fan (which activates automatically when relative humidity rises and switches off when humidity returns to a set point) is recommended. These are more expensive than simple timer fans but prevent over-ventilation in winter (which increases heat loss) while ensuring adequate ventilation when the bathroom is in use.

Ducting: the fan must duct to outside air — either through the external wall or via ductwork to the roof. Ducting to a loft or void (without external discharge) is not compliant. Duct runs should be as short as possible (each metre of duct and each bend reduces the fan's effective airflow), thermally insulated to prevent condensation in the duct, and terminated with an external grille that prevents backdraught.

Tile selection has a significant impact on the look, maintenance, and longevity of a bathroom refurbishment.

Porcelain tiles vs ceramic: porcelain tiles are denser, harder, and less porous than ceramic tiles. For bathroom floors, rectified porcelain (precision-cut edges allowing very fine grout joints) is the premium standard. For walls, either porcelain or ceramic are acceptable — ceramic is typically lighter (important for wall tile adhesion weight limits) and easier to cut.

Large-format tiles: very large tiles (600x600mm and above, or slab tiles up to 1200x2400mm) create a seamless, contemporary look with minimal grout lines. They require: a very flat, level substrate (any deviation becomes visible at the tile edges); specialist large-format tile adhesives; and experienced tilers who understand the handling and cutting requirements.

Slip resistance on floors: bathroom floor tiles must be slip-resistant. The standard is expressed as the R-rating (DIN 51130) or PTV (pendulum test value). For domestic bathroom floors, a minimum R10 (wet areas) or PTV 36 is recommended. Highly polished tiles (common for their aesthetic appeal) are often very slippery when wet — check the slip resistance rating before specifying.

Grout selection: standard cementitious grout is permeable and will stain over time in bathrooms (particularly on floors). Epoxy grout is far more resistant to staining and moisture but more expensive and harder to apply. Alternatively, specify wide (10mm+) grout joints and use a grout sealer annually. Fine grout joints (less than 3mm) are aesthetically preferable but harder to keep clean.

Shower enclosures and screens: frameless shower enclosures (glass held by minimal hardware) are the current premium standard. Framed and semi-framed enclosures are more affordable. Glass must be toughened (safety glass) — this is a legal requirement. Glass panels should be a minimum of 8mm thick for stability (6mm is the absolute minimum for frameless enclosures).

Bathroom refurbishment costs in London vary considerably depending on the size of the bathroom, the specification of sanitaryware and tiles, and the scope of the project.

Typical cost ranges for a full strip-out and refurbishment of a standard London en-suite (approximately 4–6m²):

Budget specification (standard sanitaryware, ceramic tiles, functional finishes): £4,500–£7,000 fully installed.

Mid-range specification (better-quality sanitaryware, porcelain tiles, thermostatic shower, underfloor heating): £7,000–£11,000.

High specification (premium sanitaryware brands, large-format porcelain, frameless shower, freestanding bath, smart controls): £11,000–£20,000+.

Family bathroom (larger, perhaps 8–12m²) at mid-range specification: £9,000–£16,000.

What the cost includes: strip-out and disposal; first-fix plumbing (moving or extending pipe runs); first-fix electrical (new circuits, zone-appropriate wiring); tanking; tiling (walls and floor); sanitary ware installation (bath, shower, basin, WC); second-fix plumbing (connecting fixtures); extractor fan; underfloor heating (if included); and decoration.

What the cost excludes: structural alterations (if the layout change requires wall removal); new window; specialist lighting systems beyond standard bathroom fixtures.

Programme: a typical London bathroom refurbishment takes 2–3 weeks on site (strip-out, first-fix, tanking, tiling, second-fix, snagging). Complex projects or large family bathrooms may take 3–4 weeks. The key constraint is usually tile delivery lead time — tiles ordered from specialist suppliers can take 2–4 weeks to arrive, so order early.