Bathroom Design Principles

Whether designing a tiny en suite or a luxurious spa-style wet room, a well-planned bathroom is a sound investment for any home.

Luxury bathroom

Bathrooms in a new home can be sized and designed around your needs, but with an existing room it’s important to consider early on precisely what you want. Plan how to fit your choices in the most convenient way – taking into account the position of any existing pipework or drainage.

Consider the space needed around each item, allowing approximately 700mm in front of a WC and basin and at least 1000mm beside a bath or shower. If everything is packed too tightly the doors won’t open fully and it will feel cramped and awkward. Outward opening or sliding doors will save space, and open-plan bathrooms which are part of a bedroom (sometimes screened by a partial wall) are becoming increasingly popular. 

If an architect is involved with the project, they will be able to assist with designing the room. The internal layout should be finalised before building work begins to ensure that drainage and other pipework are correctly positioned. 

Specialist bathroom companies often provide a design service free of charge, and may produce a 3D walk-through computer graphic. Obviously, they hope that you will go on to choose their products and services, but you are usually under no obligation to do so. Alternatively, you could create your own model using free online tools, such as floorplanner.com or roomstyler.com, which enable you to build, furnish and decorate virtual rooms. 

UK residents spend an average of 22 minutes in the bathroom every day, according to Abacus Bathrooms, so it makes sense to make the experience as pleasurable as possible.

Positioning bathrooms

Architects designing new homes and extensions frequently stack bathrooms on top of one another, back-to-back or in close proximity to make the best use of drainage. Dwellings constructed after 1999 will have a ground-floor WC installed, which has been designed for wheelchair access. 

If you’re considering adding a new bathroom in an existing house then additional pipework will need to be installed to supply the sanitaryware and remove waste.

Toilet location

Generally, a toilet is installed near an existing sewage stack, but if the new WC will be too far away then a macerator pumping system such as Saniflo (saniflo.co.uk) can be used to reduce the solid waste and pump it through a smaller diameter pipe to the main soil stack. This enables a bathroom to be located anywhere that conventional large bore pipework is impractical. 

Macerators cost between £250 and £1,500, and some fit neatly behind the WC itself, while other units are built into the WC or stored separately out of sight. They do have a reputation for being fairly noisy, but technology has moved on in recent years and flushing a toilet will only operate the motor for a few seconds. 

Showers

small bathroom ideaThe shower inlet requirements will depend on where the hot water is coming from. An electric shower heats the water instantly from cold and therefore will only need a cold inlet pipe. This makes them easy to install and popular with plumbers. Mains showers require both hot and cold supplies, and can have either concealed or surface-mounted connections.

Conventional British ‘gravity-fed’ plumbing in older houses is usually fed from a header tank in the attic and gives relatively poor pressure, especially when it comes to showers. This can be avoided by fitting a booster pump to improve performance or by specifying an unvented plumbing system, which provides hot water at mains pressure throughout the house. The hot water supply can either be heated directly on demand by a combination (combi) boiler, via a thermal store or in a specially designed cylinder.

Always check the water pressure requirement for your chosen shower. 

Generous shower space can make even small bathrooms feel luxurious.

Most bathrooms are prone to condensation, and an extractor fan fitted to a window or an outside wall will considerably reduce this and prevent the room from becoming damp. Natural ventilation is great if there is space for a window, and opening roof lights can be a useful option as they save wall space and provide natural light.

Wet rooms

A wet room is fully watertight with no separate shower tray. The walk-in shower area is usually level with the surrounding floor, but with a slight slope to the drain, which is fitted directly into the floor. 

Wetroom

A wet room can be the perfect solution for a small or awkwardly shaped bathroom

A wet room gives a greater feeling of space so can be the perfect solution for a small or awkwardly shaped bathroom, making it easy to move around in and more straightforward to clean – especially if you opt for a wall-mounted toilet and basin. A wet room may be easily accessed by the elderly or disabled and is practical for children, who can splash all they like.

Wetroom

Picture: The Elements wet room range from Abacus is an easy-to-install, tileable wet floor and wall board system for domestic and commercial applications.


For years wet rooms were restricted to the ground floor and had to be sited on a concrete or screeded base, but improvements in waterproofing products, such as floor membranes and shower floor formers, mean they are now suitable for both large and small spaces upstairs or down. 

In some buildings there may be difficulty installing a drain if there is insufficient space beneath the floor to create sufficient fall for the waste pipe but this can usually be overcome by using a pumped drain.

Careful planning is a key element in any new wet room installation. Important requirements include

  • good ventilation
  • effective waterproofing by tanking
  • stable (not flexible) floor which is correctly sloped with floor drainage to ensure no pooling. 

A specialist wet room company will be able to quote a price for the supply of a complete system. Alternatively, bathroom companies or architects can assist with design, building work and installation.


Bathroom installation

Building contractors or specialist bathroom companies will usually organise the various subcontractors involved, including a qualified electrician. If you’re managing the project yourself then choose a tradesperson registered with the Competent Person Scheme or go to the Chartered Institute of Plumbing and Heating Engineering to find a reputable company.

Plumbing

Plastic piping makes fitting a new bathroom far easier than working with old-style copper pipe, which requires soldering. Plastic pipe is relatively flexible and literally pushes together, sealing with an internal ‘O’ ring and securing washer. This has made plumbing far faster for plumbers and easier for the DIY market.

Electrics

Ensure that the electrics are planned from the outset and completed at an early stage, prior to fitting the sanitaryware, so that all wiring is concealed. Avoid free-standing, hanging or adjustable light fittings and any without the appropriate IP rating. 

Recessed lights and sealed units are the safest options. Unless you are using a special lighting control system no switch, apart from ceiling pull cord types, may be installed anywhere within reach of anyone using a bath or shower, and no plug and socket fittings – apart from special razor sockets – are permitted in bathrooms. 

When choosing lighting always check how far away from a water source it can be fitted, as each zone in a bathroom requires a specific IP rating. This indicates the degree of protection against water – from submersion to splashing.

Wetroom

Vivid blue tiles add drama to the Yang bath in this otherwise modest bathroom.

Building Regulations

If a bathroom is to be created in a room where there wasn’t one before, it will need to meet Building Regulations to ensure adequate ventilation and drainage, and requirements in respect of structural stability, electrical and fire safety. 

New bathroom units and fittings don’t generally require Building Regulations approval, although drainage or electrical works that form part of a refit may do.

Bathroom suites come in a wide range of colours and styles, but do think twice before selecting unusual colours or exaggerated shapes, as you could tire of them quickly. Before buying any new bathroom suite try the bath for comfort and size. Check that the various fittings will go up the stairs and allow space to move easily around the bathroom.

Wall-mounted basins and WCs create uninterrupted floor space, but you must first check with the plumber that these can be installed. If your walls are too flimsy to support a wall-hung system, it may be possible to purchase a bracing frame in conjunction with a WC unit, which will then house a concealed system.

Storage can be provided with under-basin units, built-in cupboards or wall-mounted cabinets. Clutter-free bathrooms are stylish and easier to clean, and compact sanitaryware can help to keep the room feeling orderly, but a smaller basin or bath will need taps or mixers of similar proportions. Small basins can be impractical for family bathrooms, where twin sinks may be more useful. 

Remember, the larger your bath the more water you’ll need to fill it. A standard bath measures 1700mm by 700mm and holds around 150 litres. Shower-baths are the perfect solution for smaller rooms, and are usually narrower at one end.

For any bathroom installation, think about water usage.

Low-flush toilets, low-flow showers and basin taps, and a smaller capacity bath will all help to reduce water consumption. If you have suitable cupboard space, you can even fit a grey water recycling unit to flush the toilet.

VAT on bathroom fittings

When it comes to interiors for new builds, the general rule of thumb is that you can claim back the VAT on any permanent fixtures incorporated into the house which could not be taken with you if you moved. These include sanitaryware, heating and fixed flooring.


Reader's Top Tip

Choose bathrooms, sanitaryware and tiles first when building a new house, then design the room dimensions around these to ensure that everything fits well. Never positions a toilet opposite a door, for example, and always make sure there’s enough space to conceal fixings for wall-hung sanitaryware with plenty of built-in storage.

Robert & Elizabeth Swan, who designed and built a stunning modernist home on a tight garden site.

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