It’s a small room, but an important and expensive one – and a lot can go wrong when renovating the bathroom.

We talked to some experts about the problems they’ve seen in bathroom design, and how to avoid them.

As Christchurch interior designer Alex Fulton says, “It’s a small room but a big deal.”

Fulton is a big fan of using a working document for each room that details products, professionals and timings, and sharing that document with the electrician, plumber, builder – whoever is on the job.

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“When you’ve specified something and the plumber’s just assumed it’s going to be something else, that’s when the cost comes.”

Examples of that would be if a plan called for a light in the shower and the electrician wasn’t aware of it and there was no access, or if the design included a little wall nook in the bathroom

“If it’s a bespoke idea, or you want to make something a little bit different, it’s about working backwards and going . . . if I want a shower shelf, it’s built and tiled in, that’s something the builder needs to think about before they Gib.”

People don’t really know what they want

Fulton says there’s a lot of detective work in interior design.

“My job is part detective and part counsellor, especially with a private area such as a bathroom.

“When I listen to a client’s brief I do ask, why do you want that? At that stage, a lot of people think they want something, but you have to nut down to how they live.”

Sometimes clients get “stuck” on certain ideas, such as having two sinks.

“If your favourite thing to do is brush your teeth together, then it might be a practical reason. But it’s worth asking.

“Some people like to have stuff on show, some people don’t. It’s a small room, so you need to be clever about storage."

Fulton says an example of a clever idea is to create a cavity behind a mirror “so it’s not a big clunky thing”.

Lighting is overlooked or not prioritised

When it comes to lighting, there are both practical and aesthetic considerations.

“Lighting gets missed in a lot of projects, left to the electrician to decide where the lights go. And they will tend to put that light there because it’s just what they do.”

Lighting can make room look pretty, and can be practical, such as a “pee light” with a sensor that comes on at night, and task lighting over the mirror.

“A pet peeve would be putting two different lights in a bathroom, one that’s warm and one that’s colder. That doesn’t work, especially in a small room.”

Bathrooms don’t need to be white, Fulton says.

“A lot of that is down to living where we live: We have suppliers that get products in in white, black and beige, and fair enough because retailers have to decide what they think is going to be the most popular product.”

She says specifying different colours or more unusual products can add time delays.

“That’s about lowering expectations and just making everyone aware who you’re dealing with.”

Du Bois says she often sees people making the toilet the “hero of the room”.

“I always try avoiding placing the toilet in direct view of the door leading into the bathroom.

“You can create a much better impression of the room with a beautifully designed vanity or a lovely sculptural bath which are a lot more pleasing to the eye and also encourage one to think of enjoyment instead of purely utilitarian aspects of a bathroom.”

Jamming too many things into the space makes the room uncomfortable to use, she says.

“There’s nothing worse than damaging yourself on a hook towel rail too close to the toilet or banging your head on a shelf placed too low on the wall.

The bathroom is the most humid room in the house so a breeding ground for mould, she says.

“So make sure you have good ducting. Sometimes you may even have two bathroom ducts if the space is large. One near the shower and another near the toilet.”

Not considering both task and mood lighting

Sometimes people forget to include good task light around the mirror,” Du Bois says, “but I’m also finding a lot of pre-renovated bathrooms forget to include mood lighting.”

She says we want our bathrooms to be a place to “retreat and enjoy than just a functional utilitarian space”. “To feel relaxed, you may want to control the amount of light you have in the bathroom by dimming it while you’re having a bath or using the toilet, but you’ll want something brighter if you’re putting makeup on.”

Du Bois says a big one people forget is the door swinging onto the toilet, meaning the door won’t be able to open or close properly. Cabinet doors also need clearing space.

Another spacing problem can be tapware too far away from the basin “so you can’t get your full hand under the tap”.

“We look at these details a lot – every fitting and fixture has to have a lot of careful planning so you don’t end up with an uncomfortable space.”

Renovation expert Dave Georgetti, from Auckland Central’s Refresh Renovations, says bathrooms require more thorough planning than most rooms because they’re expensive, have several plumbing connections and because waterproofing is a concern.

He has practical considerations for those considering a redesign:

Framing is important before the plasterboard goes on

“Any accessories that are going to be wall-mounted need timber framing behind them,” he says, "so mark out the locations of your heated towel rail, toilet roll holder, wall-hung vanity, shower glass track etc and the builder can put in extra nogging where required.”

Specify exactly where you want your fittings

“If you leave it to the plumber you might not like what you get.” A few points:

Electrical wiring also needs to be well-thought-out

Other than the basic lighting, extraction and a power point, some options to consider are under floor heating, another power point inside the vanity drawer for the hair dryer, soft lighting under the vanity with a sensor for night visits, wiring for an LED light and demister built into the mirror.

“Position the extractor over, or as close to the shower as possible.”

Georgetti says it’s best to choose all taps, mixers and spouts from same series, and to “try to achieve a consistent look for the other fittings”.

“If your taps are cylindrical, choose a cylindrical profile for your heated towel rail, toilet roll holder and shower door handle. If they’re square-bodied, choose a square profile throughout.”

Another tapware check is to ensure it’s suitable for the pressure of your hot water cylinder.

Georgetti points out what can happen if all the elements are not thought through:

“If it sounds like a bit of a minefield, that’s because it can be,” he says.

He recommends homeowners who lack time or confidence use a professional rather than try to project manage the bathroom themselves.