Planning a bathroom renovation that lasts

A bathroom renovation is one of the most satisfying home improvements, but it is also one where shortcuts show quickly. Damp patches, mould, cracked tiles, failing grout and a bouncy floor are all signs of a bathroom that was not built properly underneath. Most of what makes a bathroom last is hidden once it is finished, so it pays to get the planning right.

Start with the layout

Before choosing tiles and taps, decide where everything goes.

• The toilet is the hardest item to move, because it needs a large waste pipe with enough fall to reach the soil stack. Moving it far, or across the joists, can mean new pipe runs through floors and ceilings.
• Showers and baths need waste pipes with a steady fall, which affects floor heights, especially for a level-access wet room.
• Doors and windows limit where tall items can go, and an inward-opening door eats into a small room.

If the existing layout works, keeping the main items roughly where they are keeps the project simpler. If it does not, it is far better to change it now than to live with a compromise.

Check the floor before anything else

In older Oxford homes, bathrooms often sit on timber floors that have suffered from years of small leaks. Joists may be rotten, or weakened by notches cut for pipes. When the old suite comes out, have the floor checked and repaired before anything new goes in. For tiled floors, the floor also needs to be stiff enough to stop tiles and grout cracking, which often means overboarding with a suitable tile backer board.

Waterproofing is everything

Tiles and grout are not waterproof on their own. Water gets through grout joints and into the wall or floor behind. The answer is a proper waterproofing (tanking) system beneath the tiles:

• a liquid membrane or sheet system applied to the walls around the shower and bath
• sealing tapes at internal corners and the junctions between walls and floors
• collars around pipe penetrations
• a fully tanked floor for wet rooms and walk-in showers, with a properly formed fall to the drain

Use water-resistant boards rather than standard plasterboard in wet areas. On timber floors, water damage to joists is expensive to repair and entirely preventable.

Ventilation

A bathroom without effective ventilation will suffer from condensation and mould, however well it is finished. Approved Document F gives the standards.

• An intermittent extract fan for a bathroom should extract at least 15 litres per second.
• In a room with no openable window, the fan should keep running for at least 15 minutes after the room is vacated.
• Automatic controls, such as humidity sensors, should have a manual override.
• Internal doors need a gap of around 10mm under them so replacement air can flow in.

When you add a new bathroom or shower room to a house, these requirements apply to the new room, alongside a background ventilator or an alternative such as continuous extract. When you refurbish an existing bathroom, meeting the same standard is good practice. Duct the fan to the outside by the shortest practical route.

Electrics and safety

Water and electricity need care. Under Part P of the Building Regulations, electrical work in the area around a bath or shower is notifiable, as are new circuits and a new consumer unit. Use an electrician registered with a competent person scheme, such as NAPIT, who can self-certify the work. Lighting, fans and heated towel rails all need to be rated for their position in the room.

Plumbing and hot water

• Check that your boiler or hot water cylinder can supply the shower you want, particularly for larger rain heads or body jets.
• Fit isolating valves to every tap and toilet so they can be serviced without draining the system.
• Thermostatic shower valves reduce the risk of scalding and keep temperatures steady when other taps are used.
• New gas boiler work must be carried out by a Gas Safe registered engineer.

Choosing materials

• Porcelain tiles are dense, hard-wearing and low-maintenance, suitable for walls and floors.
• Natural stone looks beautiful but needs sealing and more care than porcelain, and some stones mark easily.
• Large-format tiles mean fewer grout lines to clean, but need very flat walls and floors.
• Grout and sealant choices matter. Good-quality flexible grout and sanitary silicone in movement joints prevent cracks.
• Flooring: porcelain, ceramic or vinyl designed for wet areas. Avoid laminate, which can swell when it gets wet.

Heating

Underfloor heating is a comfortable addition in a bathroom and is easiest to fit during a renovation. Electric mats are straightforward under tiles. Where a wet underfloor system is used, it can run at low temperatures, which suits heat pumps and modern boilers. Running costs depend on how you use it and your tariff, so include it in your heating plan rather than treating it as an afterthought. A heated towel rail adds warmth and helps towels dry, which reduces humidity.

Built to last

A well-built bathroom should give many years of trouble-free use. The investment in doing the hidden parts properly at the outset, the floor, the waterproofing, the ventilation and the electrics, is what makes the difference.

North Oxford Developments refurbishes bathrooms across Oxford and Oxfordshire, with our own Gas Safe registered heating engineers, NAPIT-accredited electricians, carpenters, plasterers and flooring specialists on the job. At 22 Vicarage Road in Oxford, what began as a bathroom refurbishment uncovered rotten floor structures, and the finished house now has a renovated main bathroom, a new en-suite and a ground-floor shower room, all with wet-room systems. If you are planning a new bathroom, we are happy to come and look at the space with you.