Advice and tips from Numiq: How to calculate the cost of your bathroom renovation

Surface preparation: The foundation of a successful renovation

A high quality bathroom renovation always starts with proper preparation of walls and floors. This stage has a direct impact on durability and long term performance. If preparation is rushed or overlooked, problems such as loose tiles, cracked grout or moisture penetration can occur later.

The first step is priming walls and floors, which evens out surface absorption and improves adhesion of subsequent layers. This is particularly important in older properties and new builds where substrates may be uneven or highly absorbent. Proper priming reduces adhesive consumption and ensures consistent drying. In the UK, priming typically costs around £1.00 to £2.00 per m², depending on the condition of the surface.

Next comes waterproofing, which protects the bathroom structure from moisture. Waterproofing is essential in wet areas such as shower enclosures, around bathtubs, washbasins and across floor surfaces. It is usually applied in at least two coats, with sealing tapes used in corners and around pipe penetrations. Typical costs range from £8 to £15 per m², depending on materials and complexity.

Tiling work: Combining appearance and performance

Once surfaces are prepared, wall and floor tiling can begin. This phase has a major influence on the overall look and usability of the bathroom. When choosing tiles, it is important to consider not only design, but also slip resistance, water absorption and resistance to cleaning agents.

The cost of tiling work varies based on tile size and type. Standard formats up to approximately 400 × 400 mm usually cost between £45 and £65 per m² for labour. Large format tiles, such as 600 × 1200 mm, require greater precision and experience and typically cost between £70 and £90 per m².

An essential part of tiling is grouting, which protects the substrate from moisture and dirt while contributing to a clean finish. Well executed grouting reduces the risk of mould and extends the lifespan of the tiled surface. Grouting generally costs around £3 to £5 per m².

Installation of sanitary fittings: Comfort and practicality

After tiling is complete, sanitary fittings can be installed. Installing a washbasin including connection to water supply and waste typically costs between £120 and £180 per unit, depending on the design and mounting method.

WC installation usually falls within the range of £180 to £300. Wall hung toilets require a concealed frame system, which increases costs but provides a modern appearance and easier cleaning.

Installing a bathtub generally costs between £250 and £400. If the bathtub needs to be boxed in or tiled, additional labour and material costs should be expected.

Shower area: A modern and space efficient solution

Showers are increasingly popular in bathroom renovations due to their practicality and space saving design. To ensure long term performance, correct floor falls and thorough waterproofing are essential.

The floor is typically formed with a gradient of 1 to 2 percent towards the drain. This process includes substrate preparation, forming the fall, waterproofing and final tiling. The cost for a fully constructed shower area including waterproofing and tiling generally ranges from £90 to £160 per m², depending on design and materials used.

Plumbing work: The technical backbone of the bathroom

Plumbing work forms the technical core of any bathroom renovation. It includes installing new water and waste pipework, replacing old systems and connecting fittings and sanitary ware. In older homes, replacing outdated pipes is often advisable to avoid leaks or pressure issues in the future.

In the UK, plumbing work typically costs between £60 and £90 per hour. Larger projects may take several days to complete. This is not an area where cutting costs is recommended, as mistakes can lead to expensive repairs later.

Bathroom renovation as a long term investment

A bathroom renovation is not just about appearance. It is an investment in comfort, safety and the long term value of your property. Proper surface preparation, reliable waterproofing, precise tiling, professional plumbing and careful installation of sanitary fittings ensure a bathroom that performs reliably for many years.

With a transparent building work price list and cooperation with experienced professionals, you can plan your budget realistically and avoid unpleasant surprises. Since the bathroom is used every day, investing in quality workmanship and materials is always worthwhile.